| mycorrhizal and non-mycorrhizal lactuca sativa plants exhibit contrasting responses to exogenous aba during drought stress and recovery. | the arbuscular mycorrhizal (am) symbiosis enhances plant tolerance to water deficit through the alteration of plant physiology and the expression of plant genes. these changes have been postulated to be caused (among others) by different contents of abscisic acid (aba) between am and non-am plants. however, there are no studies dealing with the effects of exogenous aba on the expression of stress-related genes and on the physiology of am plants. the aim of the present study was to evaluate the i ... | 2008 | 18469324 |
| identification, genetic localization, and allelic diversity of selectively amplified microsatellite polymorphic loci in lettuce and wild relatives (lactuca spp.). | selectively amplified microsatellite polymorphic locus (sampl) analysis is a method of amplifying microsatellite loci using generic pcr primers. sampl analysis uses one aflp primer in combination with a primer complementary to microsatellite sequences. sampl primers based on compound microsatellite sequences provided the clearest amplification patterns. we explored the potential of sampl analysis in lettuce to detect pcr-based codominant microsatellite markers. fifty-eight sampls were identified ... | 1997 | 18464878 |
| [calcium distribution in the central cell of lettuce (lactuca sativa l.) before and after pollination]. | potassium antimonite precipitation was used to locate calcium in the central cell of lettuce (lactuca sativa l.) before and after pollination. at 3d before anthesis, two polar nuclei of central cell separately located at two polarity of the cell, and few calcium precipitates (ppts) appeared in the polar nuclei and cytoplasm, but some ppts in its small vacuoles. at 2d before anthesis, two polar nuclei moved toward the middle of the cell and fused to form a secondary nucleus, and the ppts evidentl ... | 2008 | 18464591 |
| salt in irrigation water affects the nutritional and visual properties of romaine lettuce (lactuca sativa l.). | the influence of salinity stress on the growth, appearance, and nutritional compounds, especially phenolic compounds and carotenoids, of romaine lettuce (lactuca sativa l.), a low salt tolerant plant, was studied. the dry weight, height, and color of the lettuce plants were significantly changed by long-term irrigation (15 days) with higher nacl concentration (i.e., >100 mm). however, no significant differences were observed in the growth and appearance among the control, all short-term treatmen ... | 2008 | 18439016 |
| development of a biomarker for metal bioavailability: the lettuce fatty acid composition. | because lactuca sativa l. is a plant widely used in ecotoxicological analyses, a study was developed to determine whether the fatty acid composition of lettuce leaves could be used as an additional biomarker of soil contamination by metals such as pb, cu, zn, and cd. unlike seed germination or seedling growth, the fatty acid composition of lettuce leaves differed significantly between uncontaminated and field metal-contaminated soils. hence, this lipid biomarker might provide an early indication ... | 2008 | 18419182 |
| environmental fate and effects of nicotine released during cigarette production. | a variety of test methods were used to study the gradation, bioaccumulation, and toxicity of nicotine. studies included determination of the octanol-water partition coefficient, conversion to co2 in soil and activated sludge, and evaluation of the effects on microbiological and algal inhibition as well as plant germination and root elongation. the partitioning of nicotine between octanol and water indicated that nicotine will not bioaccumulate regardless of the ph of the medium. the aqueous and ... | 2008 | 18399728 |
| preparation and phytotoxicity of novel kaurane diterpene amides with potential use as herbicides. | novel kaurane ditepene monoamides were synthesized in good yields directly from kaurenoic ( 1) and grandiflorenic ( 2) acids and unprotected symmetrical diamines, using a modified protocol for monoacylation. amides from 1 and 2 and monoamines were also obtained and tested against seed germination and growth of radicle and shoot of lactuca sativa (lettuce), at 10 (-3), 10 (-5), and 10 (-7) m. amides from symmetrical diamines showed significant inhibitory activity at higher concentrations. | 2008 | 18393433 |
| biotic interactions modify the transfer of cesium-137 in a soil-earthworm-plant-snail food web. | the present study investigated the possible influence of the earthworm aporrectodea tuberculata on the transfer of cesium-137 ((137)cs) from a contaminated (130 bq/kg) deciduous forest soil to the lettuce lactuca sativa and to the snail cantareus aspersus (formerly helix aspersa) in two laboratory experiments. in the first experiment, the international organization for standardization 15952 test was used to expose snails for five weeks to contaminated soil with or without earthworms. in these co ... | 2008 | 18266477 |
| separating the effects of hypobaria and hypoxia on lettuce: growth and gas exchange. | the objectives of this research were to determine the influence of hypobaria (reduced atmospheric pressure) and reduced partial pressure of oxygen (po2) [hypoxia] on carbon dioxide (co2) assimilation (c(a)), dark-period respiration (dpr) and growth of lettuce (lactuca sativa l. cv. buttercrunch). lettuce plants were grown under variable total gas pressures [25 and 101 kpa (ambient)] at 6, 12 or 21 kpa po2)(approximately the partial pressure in air at normal pressure). growth of lettuce was compa ... | 2007 | 18251894 |
| chromosomal study of lettuce and its allied species (lactuca spp., asteraceae) by means of karyotype analysis and fluorescence in situ hybridization. | in this study, in addition to the karyotype analysis, the chromosomal distributions of 5 s and 18 s rdnas, and the arabidopsis-type (t3ag3) telomeric sequences were detected by means of fluorescence in situ hybridization (fish) to promote the information of chromosomal organization and evolution in the cultivated lettuce and its wild relatives, l. sativa, l. serriola, l. saligna and l. virosa. the karyotype analysis revealed the dissimilarity between l. virosa and the remaining species. in all f ... | 2007 | 18215246 |
| postharvest changes in water status and chlorophyll content of lettuce (lactuca sativa l.) and their relationship with overall visual quality. | the purpose of this study was to evaluate water status, chlorophyll content (c), and overall visual quality (ovq) of fresh butter lettuce (lactuca sativa var. lores) as well as these indexes' evolution during storage and their relationships, if any. whole lettuce plants were stored at optimal postharvest conditions (0 to 2 degrees c and 97% to 99% relative humidity). measured parameters during each sampling day were relative water content (rwc), water content (wc), free water (fw), bound water ( ... | 2008 | 18211369 |
| effect of methyl jasmonate on phenolic compounds and carotenoids of romaine lettuce (lactuca sativa l.). | the effect of exogenous methyl jasmonate (meja) on antioxidative compounds of romaine lettuce ( lactuca sativa l.) was investigated. lettuces were treated with various meja solutions (0, 0.05, 0.1, 0.25, and 0.5 mm) before harvest. total phenolic compounds content and antioxidant capacity of romaine lettuce significantly increased after meja treatments (0.1, 0.25, and 0.5 mm). the total content of phenolic compounds of the romaine lettuce treated with 0.5 mm meja (31.6 microg of gallic acid equi ... | 2007 | 17990849 |
| [studies on the calcium distribution in developing synergids of lettuce (lactuca sativa l.)]. | potassium antimonite was used to locate calcium in the synergids of lettuce (lactuca sativa l) during their development. the two synergids on 3d before anthesis formed evident polarity with most cytoplasm located in the micropylar end and nucleus in the middle and a big vacuole in the chalazal end. at this time, calcium precipitates were a few in both cells. calcium precipitates in the two synergids began to increase on 2d before anthesis. synergid wall in the micropylar end thickened on 1d befo ... | 2007 | 17966463 |
| cinnamic ester derivatives from oxalis pes-caprae (bermuda buttercup). | seven new cinnamic ester derivatives ( 1- 7) were isolated from a methanol extract of the fresh leaves and twigs of oxalis pes-caprae (bermuda buttercup). the structures of these new compounds were determined by spectroscopic data interpretation. the effects of compounds 1- 7 on the germination and growth of lactuca sativa (lettuce) were studied. | 2007 | 17922549 |
| relationship between lead uptake by lettuce and water-soluble low-molecular-weight organic acids in rhizosphere as influenced by transpiration. | the relationship between pb uptake by leaf lettuce ( lactuca sativa l.) and water-soluble low-molecular-weight organic acids (lmwoas) in rhizosphere, as influenced by transpiration (high and low), has been studied. studies were carried out by culturing lettuce plants grown for 2 weeks in pots filled with quartz sand mixed with anion-exchange resin and then for 30 days in a greenhouse. the potted lettuce plants were subjected to stress by the addition of pb(no 3) 2 solutions (100, 200, and 300 mg ... | 2007 | 17894455 |
| an assessment of the role of ethylene in mediating lettuce (lactuca sativa) root growth at high temperatures. | growth of temperate lettuce (lactuca sativa) plants aeroponically in tropical greenhouses under ambient root-zone temperatures (a-rzts) exposes roots to temperatures of up to 40 degrees c during the middle of the day, and severely limits root and shoot growth. the role of ethylene in inhibiting growth was investigated with just-germinated (24-h-old) seedlings in vitro, and 10-d-old plants grown aeroponically. compared with seedlings maintained at 20 degrees c, root elongation in vitro was inhibi ... | 2007 | 17728295 |
| withanolides from jaborosa kurtzii. | two new withanolides were isolated and characterized from the aerial parts of jaborosa kurtzii, namely, jaborosalactone 43 (1), with a spiranoid delta-lactone at c-22, and jaborosalactone 44 (2), a 12-oxowithanolide, which may function as a biosynthetic precursor to 1. these new compounds were fully characterized by a combination of spectroscopic methods. compound 1 showed selective phytotoxicity toward a dicotyledon species, lactuca sativa (lettuce). | 2007 | 17711343 |
| antifeedant and phytotoxic activity of cacalolides and eremophilanolides. | the antifeedant effect of six cacalolides and six eremophilanolides was tested against the herbivorous insects spodoptera littoralis, leptinotarsa decemlineata, and myzus persicae. the test compounds included several natural products isolated from senecio madagascariensis (14-isovaleryloxy-1,2-dehydrocacalol methyl ether, 4), s. barba-johannis (13-hydroxy-14-oxocacalohastine, 5; 13-acetyloxy-14-oxocacalohastine, 6) and s. toluccanus [6-hydroxyeuryopsin, 7; 1(10)-epoxy-6-hydroxyeuryopsin, 9; tolu ... | 2017 | 17708441 |
| toxicity assessment of a complex industrial wastewater using aquatic and terrestrial bioassays daphnia pulex and lactuca sativa. | aquatic and terrestrial bioassays were used to assess toxicity at several stages in an industrial wastewater treatment plant that processes 400 l/s from a complex influent formed by wastewater from 135 industries. daphnia pulex and lactuca sativa were used to assess and compare toxicity between the influent wastewater and effluent wastewater from an activated sludge process, and compare their relationship with physicochemical parameters of biological oxygen demand (bod); chemical oxygen demand ( ... | 2007 | 17680481 |
| effects of genotype and transpiration rate on the uptake and accumulation of perchlorate (clo4-) in lettuce. | although evidence of perchlorate accumulation in plants exists, there is a scarcity of information concerning the key factors and mechanisms involved. to ascertain whether genotypic variation in perchlorate accumulation occurs within lettuce, hydroponic plant uptake experiments were conducted with five types of lettuce (lactuca sativa l.), which were grown to market size atthree perchlorate (clo4-) concentrations (1, 5, or 10 microg/l). perchlorate accumulated in the leafy tissues to varying amo ... | 2007 | 17539550 |
| ecotoxicological tests assessment of soils polluted by chromium (vi) or pentachlorophenol. | carbon mineralisation and plant germination and growth (lactuca sativa seeds) tests have been performed in two soils of different properties, experimentally spiked with pentachlorophenol (pcp) or cr (vi), in concentrations between 0.001 and 1000 mg kg(-1). the evaluation has been done considering the following parameters of carbon transformation test: soil cumulative basal respiration after 14 days incubation, substrate induced respiration after 12 h of glucose addition, and, in the plant germin ... | 2007 | 17379274 |
| molecular characterisation of lac s 1, the major allergen from lettuce (lactuca sativa). | ige sensitisation to non-specific lipid transfer proteins (nsltp), e.g., pru p 3 the major allergen from peach and most important allergenic ltp, is strongly associated with severe symptoms in food allergic patients. lac s 1, a member of the nsltp protein family, was recently identified as major allergen in lettuce (lactuca sativa), but has not yet been investigated on the molecular basis. | 2007 | 17349693 |
| qtls for shelf life in lettuce co-locate with those for leaf biophysical properties but not with those for leaf developmental traits. | developmental and biophysical leaf characteristics that influence post-harvest shelf life in lettuce, an important leafy crop, have been examined. the traits were studied using 60 informative f9 recombinant inbed lines (rils) derived from a cross between cultivated lettuce (lactuca sativa cv. salinas) and wild lettuce (l. serriola acc. uc96us23). quantitative trait loci (qtls) for shelf life co-located most closely with those for leaf biophysical properties such as plasticity, elasticity, and br ... | 2007 | 17347132 |
| determination of phytotoxicity of soluble elements in soils, based on a bioassay with lettuce (lactuca sativa l.). | in this work the different concentrations of soluble elements in soils from natural (peridotitic soils) and anthropogenic (soils affected by a pyrite-mine spill) origin, are used to determine the phytotoxicity in lettuce (lactuca sativa l.). the solutions are obtained from soil:water extracts (1:1), having neutral ph and high concentrations of as, pb, zn, mn, co and ni, with values exceeding the toxic level for soil solution [bohn hl, mcneal bl, o'connor ga. soil chemistry, wiley interscience. w ... | 2007 | 17316769 |
| preparation of 2h-furo[2,3-c]pyran-2-one derivatives and evaluation of their germination-promoting activity. | the butenolide, 3-methyl-2h-furo[2,3-c]pyran-2-one (1), has recently been identified as the germination stimulant present in smoke that promotes the germination of seeds from a wide range of plant species. in this paper, we describe the preparation of a number of analogues of 1 and compare their efficacy in promoting seed germination of three highly smoke-responsive plant species, lactuca sativa l. cv. grand rapids (asteraceae), emmenanthe penduliflora benth. (hydrophyllaceae), and solanum orbic ... | 2007 | 17316021 |
| phytotoxicity of secondary metabolites from aptenia cordifolia. | from the fresh leaves or twigs of aptenia cordifolia, a total of 29 compounds were isolated, including the new tetranoroxyneolignan 18, the new dilignan 19, and the beta-ionone derivative 27, previously only known as a synthetic compound, together with 26 known compounds. the structures of the new products were determined by (1)h-, (13)c-, and 2d-nmr, as well as hr-ms analyses. the phytotoxic effects of the isolates on the germination and growth of the dicotyledon lactuca sativa l. (lettuce) wer ... | 2007 | 17311224 |
| polyphenol content and antioxidative activity in some species of freshly consumed salads. | ten genotypes belonging to lactuca sativa, cicorium intybus, plantago coronopus, eruca sativa, and diplotaxis tenuifolia and used in fresh mixed salads were investigated for their polyphenol contents. flavonoids and hydroxycinnamic acids were characterized by high-performance liquid chromatography (hplc)/diode array detection/mass spectrometry. quercetin, kaempferol, luteolin, apigenin, and crysoeriol derivatives were identified; hydroxycinnamic acids were all caffeoyl derivatives. the total pol ... | 2007 | 17279769 |
| genetic distance sampling: a novel sampling method for obtaining core collections using genetic distances with an application to cultivated lettuce. | this paper introduces a novel sampling method for obtaining core collections, entitled genetic distance sampling. the method incorporates information about distances between individual accessions into a random sampling procedure. a basic feature of the method is that automatically larger samples are obtained if accessions are further apart and smaller samples if accessions are closer together. genetic distance sampling can be used in conjunction with predefined stratifications of the accessions. ... | 2007 | 17180377 |
| hydroxamic acids in secale cereale l. and the relationship with their antifeedant and allelopathic properties. | contents of the hydroxamic acids 2,4-dihydroxy-1,4-benzoxazin-3-one (diboa), and 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (dimboa) in leaves and roots of 14 cultivars of rye, secale cereale l., were determined. dynamics of accumulation in three cultivars were evaluated. diboa was the main cyclic hydroxamic acid in leaves but the contents differed significantly between the cultivars. both diboa and dimboa were present in the roots. maximum concentration of diboa in leaves and dimboa in roots ... | 2015 | 17137112 |
| absorption of selenium by lactuca sativa as affected by carboxymethylcellulose. | several organic compounds of high molecular weight present in soil interact with selenium and may act as active binding agents affecting its availability in soil, and, consequently, selenium uptake by plants. this study is aimed at investigating the effects of polysaccharides on selenium speciation in soil and on selenium absorption by lactuca sativa l. plants. three-week-old seedlings were transplanted into pots filled with soil, and sodium selenite at rates of 1.5 and 5mgsekg(-1) of soil, or s ... | 2007 | 17107704 |
| cadmium assimilation in the terrestrial isopod, porcellio dilatatus--is trophic transfer important? | terrestrial isopods have become important tools for the ecotoxicological assessment of metal-contaminated soils. their value as an invertebrate model is partly because of their extraordinary capacity to bioaccumulate toxic metals from the environment. replication of this accumulation process in the laboratory has in the past relied on the amendment of organic food substrates through the addition of inorganic metal salts. however, the bioavailability of the metals when presented through doping re ... | 2006 | 17055036 |
| [calcium distribution in the egg cell, zygote and proembryo of lettuce (lactuca sativa l.)]. | potassium antimonite precipitation was used to located calcium in the egg cells (before and after anthesis), zygotes and proembryos of lettuce (lactuca sativa l.). a few calcium precipitates (ppts) were located in the small vacuoles of cytoplasm of egg cell at 3 d before anthesis, when egg cells just formed. then the small vacuoles fused to form some bigger vacuoles in egg cell at 2d before anthesis. calcium ppts increased evidently in the cytoplasm and nucleus of egg cells at this time. at 1d b ... | 2006 | 16944569 |
| temporal and positional relationships between mn uptake and low-ph-induced root hair formation in lactuca sativa cv. grand rapids seedlings. | we investigated whether low-ph-induced manganese (mn) deficiency causes low-ph-induced root hair formation in lettuce seedlings. both the number and length of root hairs increased in 0 microm mn (mn-free) at ph 6 and decreased in 3 mm mn (excess mn) at ph 4 compared with the values in 10 microm mn (normal mn). these results indicate an inhibitory effect of mn on both root hair initiation and elongation. the time dependency of root hair induction caused by mn deficiency corresponded to that cause ... | 2006 | 16850119 |
| structures of bioactive carexanes from the roots of carex distachya desf. | four metabolites, named carexanes i-l, have been isolated from the roots of carex distachya desf, an herbaceous plant living in the mediterranean maquis, together with three known compounds, already isolated from the aerial part of the plant. all the compounds have been characterized on the basis of their spectroscopic properties. carexane i derived from the lose of a proton from the c-18 carbon of an intermediate isopropyl cation. its stereostructure has been elucidated by mosher's method, noes ... | 2006 | 16730033 |
| photosynthetic parameters as indicators of trinitrotoluene (tnt) inhibitory effect: change in chlorophyll a fluorescence induction upon exposure of lactuca sativa to tnt. | trinitrotoluene, as a compound of conventional explosive, may cause inhibitory effect on terrestrial plants. when lactuca sativa was exposed to different concentrations of trinitrotoluene (32-1000 mg/kg), photosynthetic process was investigated by using rapid chlorophyll fluorescence kinetic and pulse modulated fluorometry. the decrease of chlorophyll a variable fluorescence was seen to be caused by the deactivation of photosystem ii reaction centers. we found for rapid variable fluorescence to ... | 2006 | 16721675 |
| effects of light level, time of harvest and position within field on the variability of tissue nitrate concentration in commercial crops of lettuce (lactuca sativa) and endive (cichorium endiva). | seven commercial crops of lettuce and one crop of endive were sampled in order to study the variability in plant tissue nitrate concentration (tnc). assuming that an appropriate sampling pattern was employed, ten plants were sufficient to give an acceptable estimate of the mean tnc. short-term shading (24-48 h) had no significant effects on mean tnc, unlike the increase in tnc known to occur following dull periods 10-14 days before harvest. the effect on tnc of time of day harvested was signific ... | 2006 | 16644593 |
| efficient and stable transformation of lactuca sativa l. cv. cisco (lettuce) plastids. | transgenic plastids offer unique advantages in plant biotechnology, including high-level foreign protein expression. however, broad application of plastid genome engineering in biotechnology has been largely hampered by the lack of plastid transformation systems for major crops. here we describe the development of a plastid transformation system for lettuce, lactuca sativa l. cv. cisco. the transforming dna carries a spectinomycin-resistance gene (aada) under the control of lettuce chloroplast r ... | 2006 | 16604461 |
| transfer of cd, cu, ni, pb, and zn in a soil-plant-invertebrate food chain: a microcosm study. | the transfer of cd, cu, ni, pb, and zn was evaluated in a soil-plant (lettuce, lactuca sativa)-invertebrate (snail, helix aspersa) food chain during a microcosm experiment. two agricultural soils, polluted and unpolluted, were studied. lettuce was cultivated for eight weeks before introduction of snails into the microcosms (m-snails). in a parallel experiment, snails were exposed to lettuce only (i.e., without soil) in simpler exposure devices called containers (c-snails). snail exposure duratio ... | 2006 | 16566167 |
| preferential inhibition of the lycopene epsilon-cyclase by the substituted triethylamine compound mpta in higher plants. | in addition to the usual complement of carotenoids found in the plant leaf tissues, lettuce (lactuca sativa), unusually, possesses large amounts of the diol lactucaxanthin. this carotenoid possesses two epsilon-end-groups and its presence provides a good model in which to study the effects of the substituted triethylamine compound 2-(4-methylphenoxy)triethylamine (mpta) on the cyclisation of beta- and epsilon-end-groups during the biosynthesis of carotenoids. treatment with 10 or 20microm mpta s ... | 2006 | 16455351 |
| effect of ozonated water treatment on microbial control and on browning of iceberg lettuce (lactuca sativa l.). | we examined the effect of ozonated water treatment on microbial control and quality of cut iceberg lettuce (lactuca sativa l.). fresh-cut lettuce was washed in ozonated water (3, 5, and 10 ppm) for 5 min at ambient temperature. the native bacterial population on the lettuce declined in response to a rise in ozone concentration. however, there was no further bacterial reduction (1.4 log cfu/g) above 5 ppm ozone. although ozonated water treatment increased the phenylalanine ammonia lyase (pal) act ... | 2006 | 16416913 |
| terpenoids and phenol derivatives from malva silvestris. | a sesquiterpene and a tetrahydroxylated acyclic diterpene as well as two known monoterpenes, 6 c(13)nor-terpenes and 11 aromatic compounds were isolated from the water extract of malva silvestris. the structures of the compounds were determined by spectroscopic nmr and ms analysis. effects of these compounds on germination and growth of dicotyledon lactuca sativa l. (lettuce) were studied in the 10(-4)-10(-7)m concentration range. | 2006 | 16403542 |
| isolation and characterization of new lignans from the leaves of cestrum parqui. | three new compounds, a sesquilignans, an oxyneolignan and a norlignan, have been isolated from the aqueous fraction of cestrum parqui. all of the compounds have been identified on the basis of their spectroscopic properties and tested on the species lactuca sativa and lycopersicon esculentum to evaluate their phytotoxic activity. | 2006 | 16401562 |
| nitric oxide functions as a positive regulator of root hair development. | the root epidermis is composed of two cell types: trichoblasts (or hair cells) and atrichoblasts (or non-hair cells). in lettuce (lactuca sativa cv. grand rapids var. rapidmor oscura) plants grown hydroponically in water, the root epidermis did not form root hairs. the addition of 10 microm sodium nitroprusside (snp), a nitric oxide (no) donor, resulted in almost all rhizodermal cells differentiated into root hairs. treatment with the synthetic auxin 1-naphthyl acetic acid (naa) displayed a sign ... | 2006 | 19521473 |
| biochemical study of leaf browning in minimally processed leaves of lettuce (lactuca sativa l. var. acephala). | a series of biochemical parameters, including the concentration of total ascorbic acid (asa(tot)) and the activities of phenylalanine ammonia lyase (pal), polyphenol oxidase (ppo), and peroxidases (pods), was investigated during cold storage (72 h at 4 degrees c in the dark) in fresh-cut (minimally processed) leaves of two lettuce (lactuca sativa l. var. acephala) cultivars differing in the susceptibility to tissue browning: green salade bowl (gsb), susceptible, and red salade bowl (rsb), resist ... | 2005 | 16366683 |
| [the character of calcium distribution in developing anther of lettuce (lactuca sativa l.)]. | potassium antimonite was used to locate calcium in the anther of lettuce (lactuca sativa l) during its development. at the early stage of anther development there were few calcium granules in microspore mother cells and the cells of anther wall. after meiosis of microspore mother cells, calcium granules first appeared in the tapetal cells in which some small secretive vacuoles containing many calcium granules were formed and secreted into locule. then, the tapetal cells began to degenerate. at t ... | 2005 | 16363117 |
| a note on the measurement of genetic diversity within genebank accessions of lettuce (lactuca sativa l.) using aflp markers. | this paper discusses a statistical approach for measuring genetic diversity within genebank accessions of a self-fertilising species. this approach is applied to lettuce (lactuca sativa l.), using aflp marker data on a set of 1,390 accessions, representing six different lettuce types. knowledge of the within-accession genetic diversity is important for decisions about the way accessions have to be maintained by genebanks. it is argued that if the within-accession diversity is small, as can be ex ... | 2006 | 16333613 |
| humic substances can modulate the allelopathic potential of caffeic, ferulic, and salicylic acids for seedlings of lettuce (lactuca sativa l.) and tomato (lycopersicon esculentum mill.). | the capacity of a leonardite humic acid (lha), a soil humic acid (sha), and a soil fulvic acid (sfa) in modulating the allelopathic potential of caffeic acid (ca), ferulic acid (fa), and salicylic acid (sa) on seedlings of lettuce (lactuca sativa l.) and tomato (lycopersicon esculentum mill.) was investigated. lettuce showed a sensitivity greater than that of tomato to ca, fa, and sa phytotoxicity, which was significantly reduced or even suppressed in the presence of sha or sfa, especially at th ... | 2005 | 16302757 |
| how does glutamine synthetase activity determine plant tolerance to ammonium? | the wide range of plant responses to ammonium nutrition can be used to study the way ammonium interferes with plant metabolism and to assess some characteristics related with ammonium tolerance by plants. in this work we investigated the hypothesis of plant tolerance to ammonium being related with the plants' capacity to maintain high levels of inorganic nitrogen assimilation in the roots. plants of several species (spinacia oleracea l., lycopersicon esculentum l., lactuca sativa l., pisum sativ ... | 2006 | 16292661 |
| phytotoxic, clastogenic and bioaccumulation effects of the environmental endocrine disruptor bisphenol a in various crops grown hydroponically. | the effects of the endocrine disruptor bisphenol a (bpa) at concentrations of 10 and 50 mg l(-1) were evaluated on the germination and morphology, micronuclei (mn) content in root tip cells and bpa bioaccumulation of hydroponic seedlings of broad bean (vicia faba l.), tomato (lycopersicon esculentum mill.), durum wheat (triticum durum desf.) and lettuce (lactuca sativa l.) after 6 and 21 days of growth. in general, bpa at any dose used did not inhibit germination and early growth (6 days) of see ... | 2006 | 16292569 |
| cadmium, copper, nickel, and zinc availability in a biosolids-amended piedmont soil years after application. | concerns over the possible increase in phytoavailability of biosolids-applied trace metals to plants have been raised based on the assumption that decomposition of applied organic matter would increase phytoavailability. the objectives of this study were to assess the effect of time on chemical extractability and concentration of cd, cu, ni, and zn in plants on plots established by a single application of biosolids with high trace metals content in 1984. biosolids were applied to 1.5 by 2.3 m co ... | 2017 | 16275727 |
| new type of dual-channel pam chlorophyll fluorometer for highly sensitive water toxicity biotests. | a new type of dual-channel pam chlorophyll fluorometer has been developed, which is specialised in the detection of extremely small differences in photosynthetic activity in algae or thylakoids suspensions. in conjunction with standardised algae cultures or isolated thylakoids, the new device provides an ultrasensitive biotest system for detection of toxic substances in water samples. in this report, major features of the new device are outlined and examples of its performance are presented usin ... | 2002 | 16245142 |
| [the dynamics of calcium distribution in stigma and style of lettuce (lactuca sativa l.) before and after pollination]. | potassium antimonite was used to deposit calcium in the stigma and style of lettuce (lactuca sativa l.) before and after pollination. the stigma of lettuce is two splits. abundant calcium granules are displayed in the wall of papillae on the receptive surface of stigma before and after pollination, which may facilitate pollen germination. however, a few calcium granules in the wall of epidermis cell on no-receptive surface. calcium distribution in style presents a gradient in transmitting tissue ... | 2005 | 16231693 |
| quantitative trait loci associated with seed and seedling traits in lactuca. | seed and seedling traits related to germination and stand establishment are important in the production of cultivated lettuce (lactuca sativa l.). six seed and seedling traits segregating in a l. sativa cv. salinas x l. serriola recombinant inbred line population consisting of 103 f8 families revealed a total of 17 significant quantitative trait loci (qtl) resulting from three seed production environments. significant qtl were identified for germination in darkness, germination at 25 and 35 degr ... | 2005 | 16177902 |
| dioxygen uptake by isolated thylakoids from lettuce (lactuca sativa l.): simultaneous measurements of dioxygen uptake, ph change of the medium and chlorophyll fluorescence parameters. | the setup has been elaborated for the simultaneous measurements of dioxygen uptake, ph changes, and chlorophyll a fluorescence parameters of an isolated thylakoid suspension. using this equipment we have found at least three kinetically distinguishable components in the response of dioxygen uptake and ph increase to light intensity in the range of 0-1600 microe m(-2) s(-1). the ph changes were not observed in the presence of uncouplers (2 microm valinomycin plus 2 microm nigericin) while o(2) up ... | 2005 | 16143918 |
| [the dynamic of calcium distribution during megasporegenesis of lettuce (lactuca sativa l.)]. | potassium antimonite was used to deposit calcium in the young ovule of lettuce (lactuca sativa l.) at megasporogenesis stage to study the relationship between calcium and megaspore degeneration. at the megaspore mother cell stage, few calcium granules were formed in the cell (plate i-1, 2). after meiosis of megaspore mother cell and forming an arrayed tetrad in a line (plate i-3), three megaspores degenerated one by one from the micropyle end. in the process of degeneration, the numbers of calci ... | 2005 | 16121008 |
| three-dimensional organization of higher-plant chloroplast thylakoid membranes revealed by electron tomography. | the light-harvesting and energy-transducing functions of the chloroplast are performed within an intricate lamellar system of membranes, called thylakoid membranes, which are differentiated into granum and stroma lamellar domains. using dual-axis electron microscope tomography, we determined the three-dimensional organization of the chloroplast thylakoid membranes within cryo-immobilized, freeze-substituted lettuce (lactuca sativa) leaves. we found that the grana are built of repeating units tha ... | 2005 | 16055630 |
| ozonated water extends the shelf life of fresh-cut lettuce. | the use of ozonated water as a sanitizer to extend the shelf life of fresh-cut lettuce and the effect on the antioxidant constituents (polyphenols and vitamin c) were investigated. fresh-cut iceberg lettuce (lactuca sativa l.) was washed at 4 degrees c using three different ozonated water dips [10, 20, and 10 activated by ultraviolet c (uv-c) light mg l(-1) min total ozone dose], and the dips were compared with water and chlorine rinses. treated lettuce was packaged in air or active modified atm ... | 2005 | 15998129 |
| purification and biochemical properties of glutathione s-transferase from lactuca sativa. | a glutathione s-transferase (gst) from lactuca sativa was purified to electrophoretic homogeneity approximately 403-fold with a 9.6% activity yield by deae-sephacel and glutathione (gsh)-sepharose column chromatography. the molecular weight of the enzyme was determined to be approximately 23,000 by sds-polyacrylamide gel electrophoresis and 48,000 by gel chromatography, indicating a homodimeric structure. the activity of the enzyme was significantly inhibited by shexylgsh and s-(2,4-dinitropheny ... | 2005 | 15826502 |
| effects of kaurane diterpene derivatives on germination and growth of lactuca sativa seedlings. | kaurenoic and grandiflorenic acid, isolated from wedelia paludosa (asteraceae), some derivatives from these acids (alcohols, esters, amides, lactones, oximes) and other naturally occurring kaurane diterpenes were tested for their action on the growth of radical and shoot of lactuca sativa. gibberellic acid, ga3, a commercially available phytohormone, belonging to the same class of diterpenes, was also tested. some of the tested substances showed a remarkable activity either in the inhibition or ... | 2012 | 15787248 |
| new fusarium wilts on vegetable crops in italy. | three fusarium wilts recently observed in italy on lettuce (lactuca sativa), wild (diplo taxis spp.) and cultivated (eruca sativa) rocket and lamb's lettuce (valerianella olitoria) emerged as major production problems in lumbardy (north-western italy). aspects of biology and epidemiology of the three diseases and some possibilities of disease management are discussed. | 2004 | 15756819 |
| isotopic discrimination of zinc in higher plants. | * the extent of isotopic discrimination of transition metals in biological processes is poorly understood but potentially has important applications in plant and biogeochemical studies. * using multicollector inductively coupled plasma (icp) mass spectrometry, we measured isotopic fractionation of zinc (zn) during uptake from nutrient solutions by rice (oryza sativa), lettuce (lactuca sativa) and tomato (lycopersicon esculentum) plants. * for all three species, the roots showed a similar extent ... | 2005 | 15720681 |
| cadmium, lead and mercury in fresh and boiled leafy vegetables grown in lagos, nigeria. | vegetables, eaten fresh or boiled, are an important diet relished in many local nigerian cuisines and delicacies. increasing their production has therefore become a prime focus of governments in nigeria. in the process of production, metals capable of impairing the health of consumers are inadvertently picked up. studies were therefore conducted to determine the presence of cadmium (cd), lead (pb) and mercury (hg) in fresh and boiled leafy vegetables grown in farms close (proximal) to highways ( ... | 2004 | 15691197 |
| genetic analysis and mapping of resistance to lettuce dieback: a soilborne disease caused by tombusviruses. | a diverse collection of modern, heirloom and specialty cultivars, plant introduction (pi) accessions, and breeding lines of lettuce were screened for susceptibility to lettuce dieback, which is a disease caused by soilborne viruses of the family tombusviridae. susceptibility was evaluated by visual symptom assessment in fields that had been previously shown to be infested with lettuce necrotic stunt virus. of the 241 genotypes tested in multiple field experiments, 76 remained symptom-free in inf ... | 2005 | 15672259 |
| effect of different washing procedures on phenolic metabolism of shredded, packaged iceberg lettuce during storage. | different washing treatments applying chlorinated, ozonated, and tap water were examined for their effect on the phenolic metabolism of minimally processed iceberg lettuce (lactuca sativa l.) during storage in consumer-sized bags at 4 degrees c for up to 9 days. to eliminate problems associated with raw material inhomogeneity, processing was conducted on a pilot-plant scale under operating conditions of industrial practice. inherent product heterogeneity caused by diverse lettuce leaf tissues wa ... | 2004 | 15537312 |
| multiple genetic processes result in heterogeneous rates of evolution within the major cluster disease resistance genes in lettuce. | resistance gene candidate2 (rgc2) genes belong to a large, highly duplicated family of nucleotide binding site-leucine rich repeat (nbs-lrr) encoding disease resistance genes located at a single locus in lettuce (lactuca sativa). to investigate the genetic events occurring during the evolution of this locus, approximately 1.5- to 2-kb 3' fragments of 126 rgc2 genes from seven genotypes were sequenced from three species of lactuca, and 107 additional rgc2 sequences were obtained from 40 wild acce ... | 2004 | 15494555 |
| stomatal conductance of lettuce grown under or exposed to different light qualities. | the objective of this research was to examine the effects of differences in light spectrum on the stomatal conductance (gs) and dry matter production of lettuce plants grown under a day/night cycle with different spectra, and also the effects on gs of short-term exposure to different spectra. | 2004 | 15347557 |
| distribution and population development of nasonovia ribisnigri (homoptera: aphididae) in iceberg lettuce. | a field study was conducted to determine the distribution and development of aphid nasonovia ribisnigri (mosley) (homoptera: aphididae) populations in iceberg lettuce, lactuca sativa l. 'salinas'. lettuce plants were transplanted and caged individually in the field and inoculated with apterous n. ribisnigri at 0, 1, 2, 3, and 4 wk after transplanting in spring and fall 2002. plants were harvested 15-50 d after inoculations; numbers of alates and apterous n. ribisnigri were counted or estimated o ... | 2004 | 15279267 |
| response to ozone in two lettuce varieties on chlorophyll a fluorescence, photosynthetic pigments and lipid peroxidation. | the effect of different o3 concentrations on two lettuce (lactuca sativa l.) varieties (valladolid and morella) was investigated through chlorophyll (chl) a fluorescence parameters, photosynthetic pigments (chl a, b and total carotenoid), lipid peroxidation and crop yield. ozone fumigation caused: a decrease in maximum quantum yield of photosystem ii (psii) photochemistry (fv/fm) in mature leaves, a reduction in the non-cyclic electron flow (phipsii) and a lower capacity to reoxidize the qa pool ... | 2004 | 15246069 |
| do earthworms mobilize fixed zinc from ingested soil? | a wide range of organisms inhabit the soil and has to deal with soil-bound metals. the bioavailable fraction of metals may be estimated explicitly using the isotopic dilution technique. in the present paper, we evaluated the isotopic exchange technique for assessing the bioavailability of soil zn (using 65zn) to earthworms. to validate the technique, the worms were first exposed to various 65zn levels, and errors due to soil entrained in the gut were evaluated. this exposure indicated no effect ... | 2004 | 15224732 |
| arudonine, an allelopathic steroidal glycoalkaloid from the root bark of solanum arundo mattei. | bioassay-guided fractionation of the methanol extract of the root bark of solanum arundo mattei led to the isolation of a steroidal glycoalkaloid, designated arudonine, which was elucidated to be solasodine o-alpha-l-rhamnopyranosyl-(1-->2)-[beta-d-xylopyranosyl-(1-->3)], [alpha-l-rhamnopyranosyl-(1-->4)]-beta-d-glucopyranoside. this steroidal glycoalkaloid inhibited the growth of lettuce seedlings (lactuca sativa). | 2004 | 15184013 |
| dredged illinois river sediments: plant growth and metal uptake. | sedimentation of the illinois river in central illinois has greatly diminished the utility and ecological value of the peoria lakes reach of the river. consequently, a large dredging project has been proposed to improve its wildlife habitat and recreation potential, but disposal of the dredged sediment presents a challenge. land placement is an attractive option. previous work in illinois has demonstrated that sediments are potentially capable of supporting agronomic crops due to their high natu ... | 2004 | 15074796 |
| structure elucidation and phytotoxicity of c13 nor-isoprenoids from cestrum parqui. | twelve c(13) nor-isoprenoids have been isolated from the leaves of cestrum parqui (solanaceae). the structure (2r,6r,9r)-2,9-dihydroxy-4-megastigmen-3-one has been assigned to the new compound. all the structures have been determined by spectroscopic means and chemical correlations. the compounds showed phytotoxic effect on the germination and growth of lactuca sativa l. | 2004 | 14759548 |
| determining toxicity of lead and zinc runoff in soils: salinity effects on metal partitioning and on phytotoxicity. | when assessing cationic metal toxicity in soils, metals are often added to soil as the chloride, nitrate, or sulfate salts. in many studies, the effects of these anions are ignored or discounted; rarely are appropriate controls included. this study used five soils varying in ph, clay content, and organic matter to determine whether salinity from counter-ions contributed to or confounded metal phytotoxicity. varying rates of pb and zn were applied to soils with or without a leaching treatment to ... | 2003 | 14713044 |
| isolation and structural characterization of a water-soluble germination inhibitor from scotch thistle (onopordum acanthium) cypselas. | cypsela dormancy in scotch thistle (onopordum acanthium) may be affected by the presence of chemical inhibitors. to investigate this phenomenon, a leachate from o. acanthium cypselas was tested for its ability to inhibit germination of the cypselas from which it was derived (i.e., autoinhibition). leachates varied in their degree of autoinhibition, depending on the cypsela population from which they were prepared. overall, removal of leachate from a group of o. acanthium cypselas increased their ... | 2003 | 14682524 |
| effects of monoterpenoids, acting alone or in pairs, on seed germination and subsequent seedling growth. | we compared the potential allelopathic activity of 47 monoterpenoids of different chemical groups, by estimating their effect on seed germination and subsequent growth of lactuca sativa seedlings. apart from individual compounds, eleven pairs at different proportions were also tested. as a group, the hydrocarbons, except for (+)-3-carene, were the least inhibitory. of the oxygenated compounds, the least inhibitory were the acetates; whenever the free hydroxyl group of an alcohol turned into a ca ... | 2003 | 14682512 |
| volatile allelopathy in velvet bean (mucuna pruriens [correction of pruiens] l.) and gravity. | allelopathy caused by volatile compounds was studied with velvet bean (mucuna pruriens [correction of prueiens] l.). preparatory experiment was conducted to identify the relationship between action of volatiles and gravity. the experimental protocol was defined and tested to study on volatile allelopathy of velvet bean. root growth of lettuce (lactuca sativa l.) seedlings was inhibited by volatile gas from velvet bean seedlings planted in agripot. in this study, it was shown that ten-day velvet ... | 2003 | 14676381 |
| abscisic acid in the thermoinhibition of lettuce seed germination and enhancement of its catabolism by gibberellin. | germination of lettuce (lactuca sativa l. cv. 'grand rapids') seeds was inhibited at high temperatures (thermoinhibition). thermoinhibition at 28 degrees c was prevented by the application of fluridone, an inhibitor of abscisic acid (aba) biosynthesis. at 33 degrees c, the sensitivity of the seeds to aba increased, and fluridone on its own was no longer effective. however, a combined application of fluridone and gibberellic acid (ga3) was able to restore the germination. exogenous ga3 lowered en ... | 2004 | 14676289 |
| snp-based codominant markers for a recessive gene conferring resistance to corky root rot (rhizomonas suberifaciens) in lettuce (lactuca sativa). | the analysis of f2 progeny and derived f3 families of lactuca sativa segregating for resistance to corky root rot caused by rhizomonas suberifaciens permitted the identification of restriction fragment length polymorphism (rflp) and single nucleotide polymorphism (snp) markers linked to the recessive resistance gene cor. pcr-based markers were identified by bulked segregant analysis (bsa). allele-specific primers were generally designed with the 3 terminal base coinciding with an snp, matching o ... | 2003 | 14663524 |
| effect of hypobaric conditions on ethylene evolution and growth of lettuce and wheat. | elevated levels of ethylene occur in enclosed crop production systems and in spaceflight environments, leading to adverse plant growth and sterility. there are engineering advantages in growing plants at hypobaric (reduced atmospheric pressure) conditions in biomass production for extraterrestrial base or spaceflight environments. objectives of this research were to characterize the influence of hypobaria on growth and ethylene evolution of lettuce (lactuca sativa) and wheat (triticum aestivum). ... | 2003 | 14658387 |
| ethylene promotes the induction by auxin of the cortical microtubule randomization required for low-ph-induced root hair initiation in lettuce (lactuca sativa l.) seedlings. | transverse cortical microtubule (cmt) arrays in lettuce root epidermal cells randomize soon after a shift from ph 6.0 to ph 4.0, and this randomization is essential for root hair initiation. we investigated the hormonal regulation of cmt randomization. at ph 4.0, 1 micro m of the auxin competitive inhibitor 2-(p-chlorophenoxy)-2-methylpropionic acid (pcib), 0.1 micro m of the ethylene biosynthesis inhibitor aminoethoxyvinylglycine (avg) or 0.1 micro m of the ethylene action inhibitor ag(+) suppr ... | 2003 | 14519775 |
| environmental cadmium levels increase phytochelatin and glutathione in lettuce grown in a chelator-buffered nutrient solution. | phytochelatins are enzymatically synthesized peptides involved in metal detoxification and have been measured in plants grown at very high cd concentrations, but few studies have examined the response of plants at lower environmentally relevant cd concentrations. using an ethylenediaminetetraacetic acid (edta)-buffered nutrient medium, we have varied cd exposure and measured phytochelatin and glutathione concentrations in romaine lettuce (lactuca sativa l. var. longifolia lam. var. parris island ... | 2013 | 12931891 |
| deactivation of gibberellin by 2-oxidation during germination of photoblastic lettuce seeds. | gibberellin (ga) plays an important role in the induction of germination of photoblastic lettuce (lactuca sativa l. cv. grand rapids) seeds. we have previously shown that gene expression of a ga 3-oxidase (ls3h1) increased after a red light treatment, resulting in an increase in the endogenous content of ga1, bioactive ga. since the metabolism of gas is also important for determining the endogenous levels of bioactive gas, cdnas encoding ga 2-oxidases (lsga2ox1 and lsga2ox2, for l. sativa ga 2-o ... | 2003 | 12913300 |
| reduced allelopathic inhibition of lettuce (lactuca sativa) growth caused by velvet bean (mucuna pruriens) under 3d-clinorotation. | allelopathy between mucuna pruriens (velvet bean) and lactuca sativa (lettuce) was studied under 3d-clinorotation. growth of both roots and shoots of lettuce seedlings was suppressed by the presence of velvet bean. the degree of suppression was less on the clinostat compared to the normal static earth gravity. l-dopa (l-3, 4-dihydroxyphenylalanine) is known to be a major substance in allelopathy of velvet bean. amount of l-dopa diffused out from a sintered filter paper into agar medium was compa ... | 2003 | 12897456 |
| the nitrogen and nitrate economy of butterhead lettuce (lactuca sativa var capitata l). | quantifying and simulating the relationships between crop growth, total-nitrogen (total-n) and nitrate-n (no3--n) concentration can improve crop nutritional husbandry. in this study, the relationship between shoot relative growth rate (rgr) and shoot total-n, organic-n and no3--n concentration of hydroponically-grown lettuce (lactuca sativa var. capitata l. cv. kennedy) was described and simulated. plants were grown hydroponically for up to 74 d. nitrogen was supplied throughout (control; t1), o ... | 2003 | 12885858 |
| a new algorithm for computational image analysis of deformable motion at high spatial and temporal resolution applied to root growth. roughly uniform elongation in the meristem and also, after an abrupt acceleration, in the elongation zone. | a requirement for understanding morphogenesis is being able to quantify expansion at the cellular scale. here, we present new software (rootflowrt) for measuring the expansion profile of a growing root at high spatial and temporal resolution. the software implements an image processing algorithm using a novel combination of optical flow methods for deformable motion. the algorithm operates on a stack of nine images with a given time interval between each (usually 10 s) and quantifies velocity co ... | 2003 | 12857796 |
| role of manganese in low-ph-induced root hair formation in lactuca sativa cv. grand rapids seedlings. | root hair formation is induced by low ph in lettuce ( lactuca sativa l. cv. grand rapids) seedlings cultured in mineral medium. the role of mineral concentrations in this phenomenon was investigated, especially for manganese. when lettuce seedlings were cultured in media that were deficient in calcium (ca), manganese (mn), boron (b) or molybdenum (mo), morphological changes were induced in roots. deficiency of other nutrients had little effect on root hair formation. ca or b deficiency inhibited ... | 2003 | 12750946 |
| herbicidal, plant growth inhibitory, and cytotoxic activities of bismuthines containing aromatic heterocycles. | this work presents the herbicidal and plant growth regulatory activities of tertiary bismuthines containing heterocyclic aromatic rings of the general formula (2-c(4)h(3)x)(3)bi, where x = s (3), o (1), or nme (2). toxicity against artemia salina and herbicidal activity on lactuca sativa, trifolium pratense, and lolium multiflorum were tested. in addition to the effects on mitochondrial respiration obtained from roots of phaseolus vulgaris, these compounds also demonstrated partial radical scave ... | 2003 | 12720372 |
| [genetic ecology of rice allelopathy on receiver plant]. | in this study, 5 parental rice lines with different allelopathic potential were employed in partial diallel cross (4 x 5) to get 10 groups of f1 seeds. after testing the inhibitory effects of 5 parents and 10 f1s under different environment at different leaf stage on the shoot length of receiver plant lettuce(lactuca sativa l.), dynamic genetics of rice allelopathy and its genotype x environment effects were analyzed by using additive-dominant developmental genetic models. the results showed tha ... | 2002 | 12682960 |
| randomization of cortical microtubules in root epidermal cells induces root hair initiation in lettuce (lactuca sativa l.) seedlings. | root hair formation is induced when lettuce seedlings are transferred from liquid medium at ph 6.0 to fresh medium at ph 4.0. if seedlings are transferred to ph 6.0, no root hairs are formed. we investigated the role of microtubules in this low ph-induced root hair initiation in lettuce. at the hair-forming zone in root epidermal cells, microtubules were perpendicular to the longitudinal axis of the cell just after pre-culture. this arrangement became disordered as early as 5 min after transfer ... | 2003 | 12668782 |
| characterization and genetic analysis of a lettuce (lactuca sativa l.) mutant, weary, that exhibits reduced gravitropic response in hypocotyls and inflorescence stems. | a lettuce (lactuca sativa l.) mutant that exhibits a procumbent growth habit was identified and characterized. in two wild type (wt) genetic backgrounds, segregation patterns revealed that the mutant phenotype was controlled by a recessive allele at a single locus, which was designated weary. hypocotyls and inflorescence stems of plants homozygous for the weary allele exhibited reduced gravitropic responses compared with wt plants, but roots exhibited normal gravitropism. microscopic analysis re ... | 2003 | 12654877 |
| isolation and identification of an allelopathic substance in pisum sativum. | the residue of peas (pisum sativum l.) has allelopathic activity and the putative compound causing this inhibitory effect was isolated from a methanol extract of pea shoots. chemical structure of this compound was determined by high-resolution ms, ir and 1h nmr spectral data as pisatin. pisatin inhibited growth of cress (lepidium sativum l.) and lettuce (lactuca sativa l.) seedlings at concentrations greater than 10 and 30 microm, respectively. the doses required for 50% growth inhibition of roo ... | 2003 | 12591269 |
| germination and growth of lettuce (lactuca sativa) at low atmospheric pressure. | the response of lettuce (lactuca sativa l. cv. waldmann's green) to low atmospheric pressure was examined during the initial 5 days of germination and emergence, and also during subsequent growth to vegetative maturity at 30 days. growth took place inside a 66-l-volume low pressure chamber maintained at 70 kpa, and plant response was compared to that of plants in a second, matching chamber that was at ambient pressure (approximately 101 kpa) as a control. in other experiments, to determine short ... | 2002 | 12583399 |
| isolation and characterization of the acc synthase genes from lettuce (lactuca sativa l.), and the involvement in low ph-induced root hair initiation. | root hair formation is induced when lettuce seedlings are transferred from ph 6.0 to ph 4.0. ethylene, auxin and light are essential to this process. to investigate the role of ethylene in root hair initiation, we isolated two 1-aminocyclopropane-1-carboxylic acid (acc) synthase genes (ls-acs1 and ls-acs2). seven motifs of known acs proteins were highly conserved in ls-acs1 and ls-acs2. the ls-acs1 and ls-acs2 mrna levels were constant at ph 6.0, which were lower than that in seedlings at ph 4.0 ... | 2003 | 12552148 |
| 4,4,4-trifluoro-3-(indole-3-)butyric acid promotes root elongation in lactuca sativa independent of ethylene synthesis and ph. | we studied the mode of action of 4,4,4-trifluoro-3- (indole-3-) butyric acid (tfiba), a recently described root growth stimulator, on primary root growth of lactuca sativa l. seedlings. tfiba (100 micromoles) promoted elongation of primary roots by 40% in 72 h but inhibited hypocotyl growth by 35%. tfiba induced root growth was independent of ph. tfiba did not affect ethylene production, but reduced the inhibitory effect of ethylene on root elongation. tfiba promoted root growth even in the pres ... | 2002 | 12542053 |
| improving spinach, radish, and lettuce growth under red light-emitting diodes (leds) with blue light supplementation. | radish (raphanus sativus l. cv. cherriette), lettuce (lactuca sativa l. cv. waldmann's green), and spinach (spinacea oleracea l. cv. nordic iv) plants were grown under 660-nm red light-emitting diodes (leds) and were compared at equal photosynthetic photon flux (ppf) with either plants grown under cool-white fluorescent lamps (cwf) or red leds supplemented with 10% (30 micromoles m-2 s-1) blue light (400-500 nm) from blue fluorescent (bf) lamps. at 21 days after planting (dap), leaf photosynthet ... | 2001 | 12542027 |
| phytotoxicity of 2,4,6-trinitrotoluene (tnt) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (hmx) in spiked artificial and natural forest soils. | toxicity of 2,4,6-trinitrotoluene (tnt) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (hmx) using two terrestrial plant species, lettuce (lactuca sativa) and barley (hordeum vugare), was assessed in artificial soil (silica) and forest soil. lettuce emergence was significantly decreased after 5 days of exposure to tnt nominal spiked concentrations >/= 1,040 mg/kg dry soil in silica. barley emergence was significantly reduced after 14 days of exposure at initial (t = 0) tnt concentrations > ... | 2003 | 12520392 |
| isolation and identification of an allelopathic substance from peel of citrus junos. | the inhibitory effect of citrus junos peel on plant growth using lettuce (lactuca sativa l.) as a bioassay material was investigated, since the powder of the peel had been found to inhibit growth of weeds. basic, neutral and acidic fractions were separated from the aqueous fraction obtained from the methanol extract of c. junos peel. all fractions inhibited the growth of lettuce seedlings, but by far the greatest inhibition was observed with the neutral fraction. thus, the latter was further pur ... | 2002 | 12453578 |
| resistance to adult banded cucumber beetle (coleoptera: chrysomelidae) in romaine lettuce. | four cultivars of lettuce, lactuca sativa l., were evaluated for their resistance to the adult banded cucumber beetle, diabrotica balteata leconte, under laboratory conditions. when paired with each of the other three cultivars, leaf consumption in all possible combinations of short-term (48 h) two-choice tests among the cultivars was significantly reduced only for 'valmaine'. however, in a 48-h no-choice situation, beetles fed valmaine or 'short guzmaine' had similarly low leaf consumption, fol ... | 2002 | 12216830 |
| effect of wash water temperature and chlorination on phenolic metabolism and browning of stored iceberg lettuce photosynthetic and vascular tissues. | cut tissues from distinct anatomical locations in iceberg lettuce (lactuca sativa l.) were subjected to washing in cold (4 degrees c) and warm (47 degrees c) water with or without chlorine to assess their propensity to discoloration during storage. total protein (bradford method) and phenolic (tph; folin-ciocalteu method) contents and polyphenol oxidase (ppo; spectrophotometric method using catechol as a substrate), peroxidase (pod; guaiacol substrate), and phenylalanine ammonia-lyase (pal; phen ... | 2002 | 12137468 |
| transfer of the fungicide vinclozolin from treated to untreated plants via volatilization. | head lettuce plantlets (lactuca sativa l. var. capitata) were potted, treated with vinclozolin at the six-leaf stage according to application standards and allowed to dry for 24 h. the potted plantlets were then placed in either growth chambers with controlled temperature (20 and 25 degrees c, respectively) or in a greenhouse (approximately 12 degrees c), together with untreated spinach (spinacia oleracea l.) and standardized grass cultures (lolium multiflorum lam. ssp.) while the treated lettuc ... | 2002 | 12137060 |