Morphactin-gibberellin interaction in lettuce seed germination and seedling growth

Morphactin-butylester (a flourene-9-carboxylic acid derivative) inhibited seed germination of two strains of lettuce. Morphactin induced inhibition of germination could be partially or wholly reversed by simultaneous addition of gibberellic acid. However, gibberellic acid played very little part in reversing the inhibitory effect of morphactin on seedling growth. It is concluded that gibberellin can not reverse all the growth effects induced by morphactin.     

Morphactin-kinetin interaction in lettuce seed germination and seedling growth

Summary Butylester of morphactin (n-butyl-9-hydroxy-fluorence-(9)-carboxylate) greatly inhibited seed germination and seedling growth of two strains of lettuce, Attraktion and Hohlblättriger Butter. The inhibitory effect of morphactin on seed germination was completely overcome by kinetin but the latter chemical was ineffective in reversing the morphactin induced inhibition of seedling growth. Thus it appears probable that the two substances effect seedling growth independently.     

Inhibitory effects of monoterpenes on seed germination and seedling growth

Monoterpenes, the chemical constituents of essential oils found in plants, are known biologically active compounds. The present study was conducted to investigate the inhibitory effects of 30 monoterpenes including monoterpene hydrocarbons and oxygenated monoterpenes on seed germination and seedling growth of Amaranthus retroflexus, Chenopodium album and Rumex crispus under laboratory conditions. The monoterpenes were applied at contents of 10 and 20 microl for liquid compounds and 10 and 20 microg for solid compounds. The results show that most of the monoterpenes significantly inhibited seed germination and seedling growth of the tested plants. Oxygenated monoterpenes including beta-citronellol, nerol and terpinen-4-ol completely inhibited seed germination and seedling growth of all tested plants. Their inhibitory effects were also stronger than that of the herbicide 2,4-D. In general, monoterpenes were less effective against seed germination and seedling growth of C. album as compared with R. crispus and A. retroflexus. Phytotoxic effects of monoterpene hydrocarbons were found to be lower than those of oxygenated monoterpenes. The alcohol derivatives of oxygenated monoterpenes were also found to be more phytotoxic as compared with their acetate derivatives. Based on the present results, it can be concluded that the oxygenated monoterpenes can be used as potential bio-herbicides.     

Arabidopsis fatty acid desaturase FAD2 is required for salt tolerance during seed germination and early seedling growth

Fatty acid desaturases play important role in plant responses to abiotic stresses. However, their exact function in plant resistance to salt stress is unknown. In this work, we provide the evidence that FAD2, an endoplasmic reticulum localized ω-6 desaturase, is required for salt tolerance in Arabidopsis. Using vacuolar and plasma membrane vesicles prepared from the leaves of wild-type (Col-0) and the loss-of-function Arabidopsis mutant, fad2, which lacks the functional FAD2, we examined the fatty acid composition and Na+-dependent H+ movements of the isolated vesicles. We observed that, when compared to Col-0, the level of vacuolar and plasma membrane polyunsaturation was lower, and the Na+/H+ exchange activity was reduced in vacuolar and plasma membrane vesicles isolated from fad2 mutant. Consistent with the reduced Na+/H+ exchange activity, fad2 accumulated more Na+ in the cytoplasm of root cells, and was more sensitive to salt stress during seed germination and early seedling growth, as indicated by CoroNa-Green staining, net Na+ efflux and salt tolerance analyses. Our results suggest that FAD2 mediated high-level vacuolar and plasma membrane fatty acid desaturation is essential for the proper function of membrane attached Na+/H+ exchangers, and thereby to maintain a low cytosolic Na+ concentration for salt tolerance during seed germination and early seedling growth in Arabidopsis.     

Mapping salinity tolerance during Arabidopsis thaliana germination and seedling growth

To characterize and dissect genetic variation for salinity tolerance, we assessed variation in salinity tolerance during germination and seedling growth for a worldwide sample of Arabidopsis thaliana accessions. By combining QTL mapping, association mapping and expression data, we identified genomic regions involved in salinity response. Among the worldwide sample, we found germination ability within a moderately saline environment (150 mM NaCl) varied considerable, from >90% among the most tolerant lines to complete inability to germinate among the most susceptible. Our results also demonstrated wide variation in salinity tolerance within A. thaliana RIL populations and identified multiple genomic regions that contribute to this variation. These regions contain known candidate genes, but at least four of the regions contain loci not yet associated with salinity tolerance response phenotypes. Our observations suggest A. thaliana natural variation may be an underutilized resource for investigating salinity stress response.     

Arabidopsis thaliana seed germination and early seedling growth are inhibited by monoethanolamine salts of para-halogenated benzoic acids

Abstract

In spite of the simplicity of its molecules, the complex effects of benzoic acids on the regulation of plant growth are an increasingly attractive field of research to chemists and biologists. Halide substituted benzoic acids offer an excellent opportunity to explore the effect of electron withdrawing substituents (fluoro-, chloro-, bromo- and iodo-) on the response of plant growth stage. Under normal physiological conditions, benzoic acids are ionized molecules that exhibit low solubility in water. Monoethanolamine, a natural alkanolamine, was used to generate salts of monoethanolamine of halogenated para-substituted benzoic acids, new compounds with biological activity. This study reports on the biological effects of these substances at different concentrations on Arabidopsis thaliana seed germination and early seedling growth. Seed germination at 22°C, in a vertical position, under a photoperiod of 16 h light and 8 h darkness, was variable depending on the concentration of the compounds applied. Final germination percentages were similar for all treatments and control at 0.05 mM and 0.1 mM (exception p-Br BA and p-I MEASPBA). No germination occurred when seeds were treated with more than 0.5 mM. The results also revealed that the primary root length and the number of secondary roots are reduced in a concentration-dependent manner and also in relation to increasing atomic size of the substituents (F < Cl < Br < I). It is concluded that uptake rates of benzoic acid anions by roots decrease with a decrease in hydrophilic character of the anion and with an increase in molecular size.     

胁迫时间与非毒性离子对重金属抑制拟南芥种子发芽及幼苗生长的影响

测定了Hg²⁺、Cd²⁺、Cu²⁺、Pb²⁺单一重金属胁迫对拟南芥种子发芽和幼苗生长的影响.结果表明,重金属对幼苗生长的毒性大于对种子发芽的毒性,以抑制种子发芽的IC₅₀为指标,4种重金属的毒性顺序为Hg²⁺＞Cd²⁺＞Pb²⁺/Cu²⁺,以幼苗生长为指标,则毒性顺序为:Cu²⁺＞Hg²⁺＞Cd²⁺/Pb²⁺,并随着胁迫时间延长,种子萌发率下降.此外,不同重金属在不同发芽时段对种子的毒性也不尽相同,Cd²⁺的毒性在种子吸水后的0～12 h大于12～24 h,而Hg²⁺毒性在12～24 h大于0～12 h,其中,种皮对减轻重金属毒性起着十分重要的作用.通过非毒性离子(Ca²⁺、Mg²⁺、K⁺、Na⁺)与重金属离子(Hg²⁺、Cd²⁺、Cu²⁺、Pb²⁺)交互作用对拟南芥种子发芽及幼苗生长效应的研究发现, mmol·L^-1的Ca²⁺、Mg²⁺、K⁺、Na⁺可以增强Hg²⁺对种子发芽的毒性,但对Cd²⁺的毒性却没有影响.对于幼苗来说,Ca²⁺、Mg²⁺、K⁺、Na⁺可以显著增强Hg²⁺的毒性,Ca²⁺可以缓解Cd²⁺的毒性,但却增加Cu²⁺的毒性,K⁺可以缓解Pb²⁺对幼苗的毒害作用.最后,本文对重金属的毒害机理进行了探讨.     

Pyrimidine degradation influences germination seedling growth and production of Arabidopsis seeds

PYD1 (dihydropyrimidine dehydogenase) initiates the degradation of pyrimidine nucleobases and is located in plastids. In this study, a physiological analysis of PYD1 employing T-DNA knockout mutants and overexpressors was carried out. PYD1 knockout mutants were restricted in degradation of exogenously provided uracil and accumulated high uracil levels in plant organs throughout development, especially in dry seeds. Moreover, PYD1 knockout mutants showed delayed germination which was accompanied by low invertase activity and decreased monosaccharide levels. Abscisic acid (ABA) is an important regulator of seed germination, and ABA-responsive genes were deregulated in PYD1 knockout mutants. Together with an observed increased PYD1 expression in wild-type seedlings upon ABA treatment, an interference of PYD1 with ABA signalling can be assumed. Constitutive PYD1 overexpression mutants showed increased growth and higher seed number compared with wild-type and knockout mutant plants. During senescence PYD1 expression increased to allow uracil catabolism. From this it is concluded that early in development and during seed production PYD1 is needed to balance pyrimidine catabolism versus salvage.     

不同品种燕麦种子萌发和幼苗生长的耐盐性

利用NaCl和Na2SO4复盐溶液胁迫处理36个燕麦品种,采用培养皿纸上发芽法,进行种子萌发和幼苗的耐盐能力鉴定,通过分析盐胁迫对不同燕麦种子萌发及幼苗的影响,为燕麦品种耐盐性筛选、盐碱地燕麦栽培和耐盐育种提供理论参考.结果表明:盐分抑制种子的萌发和幼苗生长,低盐浓度(0.4%)适宜各类燕麦生长,对较耐盐的品种有促进萌发、生长的作用,盐浓度1.2%是鉴定燕麦耐盐性的适宜盐浓度;36个品种耐盐性差异较大,可划分为耐盐型、中度耐盐型、不耐盐型3类;燕麦不同品种及不同类型种子萌发的盐浓度范围达极显著差异,各耐盐指标对于燕麦耐盐性的体现存在一定的差异,发芽率、发芽指数、简易活力指数和单株干质量是主要的耐盐指标.     

加快棕种子萌发和幼苗生长的研究

棕种子萌发和幼苗生长十分缓慢 ,为了探索加快种子萌发和幼苗生长的方法 ,对棕种子进行不同处理、不同时间催芽和催芽后不同处理等试验 ,结果表明 :(1)生长调节剂 3号 ABT生根粉、吲哚丁酸和 2 ,4 - D可提高种子萌发率 ,促进幼苗生长。 (2 )播种前催芽可促使种子提前萌发 ,延长幼苗生长期 ,使当年生苗更粗壮 ;贮藏 3个月后催芽可提高 10 %～ 15%的发芽率。 (3)催芽后用 50 mg/ L和 10 0 mg/ L的 3号 ABT生根粉、或者 10 0 mg/ L的萘乙酸浸泡都可以提高幼苗出土率 ,但对幼苗生长没有明显影响。     

Effect of light on seed germination and seedling growth ofMerremia species

The seeds ofMerremia aegyptia are indifferent to light conditions for germination, which becomes 100% in the first 24 hrs. On the contrary, inM. dissecta the highest percentage was found in red light within the first 24 hrs. This difference was lost later on except in far-red. The seedling growth of the two species was least in blue and red lights, respectively. However, the growth of hypocotyl in the former species was faster than the latter.     

加快橦棕种子萌发和幼苗生长的研究

Ｄｏｎｇ棕种子萌发和幼苗生长十分缓慢,为了探索加快了萌发和细菌生长的方法,对Ｄｏｎｇ棕种子进行不同处理、不同时间催芽和催芽后不同处理等试验,结果表明：⑴生长调节剂３号ＡＢＴ生根粉、吲哚丁酸和２,４－Ｄ可提高种子萌发率,促进幼苗生长。⑵播种前催芽可促使种子提前萌发,延长幼苗生长期,使当年生苗更粗壮;贮藏３个月后催芽可提高１０％－１５％的发芽率。⑶催芽后用５０ｍｇ／Ｌ和１００ｍｇ／Ｌ的３号ＡＢＴ生根粉     

种子萌发和幼苗生长对沙丘环境的适应机制

综述了植物沙生适应机制的研究及其进展.一些植物的种子在刚成熟时具有休眠特性.种子需要适度沙埋促进萌发并实现幼苗定居,但过度沙埋则会抑制种子萌发和出苗.在沙层深处,没有萌发的种子会进入休眠状态,形成土壤种子库.幼苗通过增加节数和延长节间来适应沙埋.沙埋深度超过植物的忍耐限度会抑制幼苗生长,甚至导致幼苗死亡.沙生植物必须适应其他环境因子,如盐风与土壤盐分、昆虫采食、土壤养分亏缺等,才能在沙丘上成功生长.沙蚀可导致幼苗根系暴露并干燥脱水.一些沙漠植物的幼苗在萌发后可忍耐一段时期的干燥,水分条件得到满足之后,幼苗能够恢复生长.     

The effect of sodium fluoride on cereal seed germination and seedling growth

Abstract. Fluoride has been shown to inhibit germination and seedling establishment in barley cv. Natasha, wheat cv. Axona and rice cv. Ishikari. The concentrations of fluoride were selected so as to give a satisfactory dose-response relationship and also to relate to levels of fluoride present under natural conditions. Concentrations used were zero, 0.5, 1.0, 10 and 40 mol m⁻³ sodium fluoride. In germination studies, barley was found to be least tolerant and rice most tolerant of fluoride. The inhibition was found to be a response to fluoride itself and the observed effects were not due to pH, sodium or an unspecific effect of halide ion. Phosphate, applied at two concentration levels, was unable to overcome the inhibition. Fluoride was also shown to inhibit seedling growth. The inhibitory effects of fluoride may be accounted for by a wide range of metabolic effects including inhibition of gibberellic acid–triggered alpha amylase activity during germination, and later on to inhibition of chlorophyll synthesis in the developing leaves.     

油菜对3种作物种子萌发和幼苗生长的化感作用

油菜是我国重要的绿肥作物,除增加土壤肥力外,对后茬作物也有一定的化感作用。本文研究了不同浓度油菜浸提液(0.025、0.05和0.1 g·mL^-1)对3种作物(燕麦、玉米和向日葵)种子萌发、幼苗生长及生理生化的影响。结果表明: 油菜浸提液对3种作物种子发芽率的影响不显著,但对燕麦有“低促高抑”的趋势,对向日葵有抑制的趋势。油菜浸提液高浓度处理对燕麦幼苗根和茎长、玉米幼苗茎长以及向日葵幼苗根长起抑制作用,低浓度处理对玉米幼苗根茎长起促进作用。燕麦和向日葵幼苗在浸提液浓度为0.05 g·mL^-1时蛋白质含量最大,玉米在0.025 g·mL^-1时蛋白质含量最大,显著高于对照。3个浓度下,向日葵脯氨酸含量均显著降低,玉米脯氨酸含量在浓度为0.05 g·mL^-1时显著高于对照。玉米过氧化物酶(POD)活性在浸提液浓度为0.05 g·mL^-1时最大,向日葵POD活性在浓度为0.025 g·mL^-1时最大,与对照有显著差异,其余浓度处理与对照无显著差异。油菜浸提液浓度为0.025 g·mL^-1时显著降低了燕麦超氧化物歧化酶(SOD)活性,3种作物幼苗过氧化氢酶(CAT)活性与对照均无显著差异。加入油菜浸提液后,向日葵幼苗丙二醛(MDA)含量在浓度为0.1 g·mL^-1时显著增加,玉米幼苗MDA含量在不同浓度处理下均显著低于对照。综合分析,油菜浸提液对向日葵的化感抑制作用最强,其次为玉米、燕麦。     

青蒿素对蔬菜种子发芽和幼苗生长的化感效应

试验以菜豆、豇豆、大白菜和小白菜为对象,用不同浓度的青蒿素浸种,研究了黄花蒿产生的化感物质??青蒿素对蔬菜种子发芽及幼苗生长的影响。结果表明,青蒿素对蔬菜种子发芽和幼苗生长的化感作用表现出浓度效应和品种差异,即浓度越高,抑制作用愈强,尤以豇豆种子发芽率和小白菜生长的表现最为明显,前者的发芽率可降低75.00%,后者的苗高降幅高达88.37%,且胚根停止生长。青蒿素抑制同季和后季作物的种子发芽和幼苗生长,有利于扩大黄花蒿的生存空间,增强生存竞争优势。在黄花蒿?蔬菜种植体系中,选择抗化感作用较强的大白菜和菜豆可提高土地利用率和整体生产水平。用青蒿素浸种后,蔬菜幼苗的根系活力降低,菜豆和豇豆叶绿素含量提高,而大、小白菜降低,均可视为妨碍生长的生理原因。此外,青蒿素浸种还提高蔬菜种子可溶性糖和游离氨基酸含量,推测青蒿素对种子水解酶活性的影响较小,但抑制合成酶催化的生化反应,导致代谢紊乱,抑制幼苗生长。     

Allelopathic effects of sunflower extracts on mustard seed germination and seedling growth

The allelopathic potential of two cultivars of sunflower (Helianthus annuus L.) Lech and Ogrodowy was studied. Leaf aqueous extracts of sunflower at 2.5, 5, and 10 % (m/v) concentrations were applied to determine their effect on mustard (Sinapis alba) seed germination and seedlings growth under laboratory conditions. Increasing concentration of aqueous extracts of sunflower inhibited seed germination, up to almost complete failure of germination, observed in the presence of 10 % extract from sunflower cv. Ogrodowy. The decrease in germinability was well correlated with increased membrane deterioration, assayed as electrical conductivity and enhanced lipid peroxidation, detected as increased malondialdehyde content.     

1,2,4-三氯苯对水稻种子萌发及幼苗生长的毒性机理

以水稻为试材,采用水培方法研究了1,2,4-三氯苯(1,2,4-TCB)对水稻种子萌发、幼苗生长、叶绿素含量、蛋白质含量、脯氨酸含量、细胞膜通透性的影响.结果表明,水稻种子的萌发率和活力指数随1,2,4-TCB处理浓度的升高而逐渐降低,呈现一定的浓度-效应关系,高浓度(80和100 mg·L^-1) 1,2,4-TCB处理组水稻种子的活力指数仅为对照组的7. 89％和1.92％,水稻幼苗的株高和根长均受到抑制,表现出一定的浓度-效应和时间-效应关系.水稻叶片的叶绿素a、叶绿素b、总叶绿素和蛋白质含量均随1,2,4-TCB浓度的升高而降低.水稻叶片游离脯氨酸含量和细胞膜的通透性随处理浓度的升高而增加.当1,2,4-TCB处理浓度＞15 mg·L^-1时,游离脯氨酸含量和叶片细胞膜的通透性急剧增加,与对照组相比各组差异均显著(P＜0.01).这表明1,2,4-TCB对水稻幼苗的损伤是一个复杂的过程,其机理可能与1,2,4-TCB使植物细胞膜、细胞内蛋白质和细胞器结构和功能损伤有关.