高粱幼苗对高渗培养液的生长、生理反应及其抗逆性

抗旱性不同的高梁品种(3197B和三尺三)对高渗培养液的生长、生理反应有相同的趋势,如生长受抑、水势下降、相对透性、游离脯氨酸含量和在总游离氨基氮中游离脯氨酸氮比例的增加等,但品种间的变化幅度有明显差别。特别在较严重干旱处理下(-10巴)不抗旱型的品种三尺三生长受抑,水势下降,相对透性增加要大于抗旱型的品种3197B,而游离脯氨酸含量和在总游离氨基氮中游离脯氨酸氮比例的增加要小于3197B。随着干旱处理时间的延长,高梁幼苗有一种自动调节或适应能力。表现在生长、水势、相对透性、游离脯氨酸含量和在总游离氨基氮中游离脯氨酸氮比例的恢复。但恢复的能力品种间有差别,3197B大于三尺三。本文并讨论了水势、相对透性和游离脯氨酸含量增加的能力与抗旱性的关系。     

水分胁迫下不同抗旱类型品种对氮素营养反应的比较研究

实验结果表明,小麦受到水分胁迫时,游离脯氨酸大量积累,胁迫缓慢加重时,渗透调节能力增强,适当的氮素营养,可增强渗透调节作用,有助于干旱下维持膨压,提高NR酶活性和净光合速率。水地型品种对水分和氮素营养都较敏感,叶片水势、饱和渗透势、NR酶活性、游离脯氨酸含量的变化都较旱地型品种大,旱地型品种在受旱时水分状况较稳定,生理代谢变化幅度较小,但两类旱地品种对氮素营养的反应不同。旱肥型较旱薄型敏感。水分胁迫下,水地型品种渗透势下降较多,渗透调节幅度较大,是对逆境更敏感或实际受到的胁迫较重的表现。     

转拟南芥P5CS1基因增强羽衣甘蓝的耐旱性

为提高羽衣甘蓝的耐旱性,本文将拟南芥Δ1-吡咯啉-5-羧酸合成酶（P5CS1）基因经农杆菌介导转入羽衣甘蓝植株中,检测转基因株系与野生型植株在干旱胁迫下P5CS1 mRNA表达量、幼苗脯氨酸含量、株系根系性状、整株干重、鲜重和整株存活率。结果表明,在15%PEG6000渗透胁迫下,转基因植株的P5CS1基因mRNA表达量明显增加,转基因植株脯氨酸含量是野生型的2.4倍;主根长、最长侧根长、侧根数目、整株干重和鲜重均高于野生型,干重/鲜重则低于野生型,转基因植株的平均存活率为78%,极显著高于野生型。数据显示,AtP5CS1基因在羽衣甘蓝中的表达明显改善了转基因植株的耐旱性。     

玉米对渗透胁迫的反应和生理适应

利用不同渗透势的培养液模拟土壤干旱条件,研究了玉米杂交种“中单2号”在此条件下的生长和生理的变化。实验表明,各指标对于渗透胁迫的变化敏感性顺序为叶片延伸速率、叶水势、脯氨酸含量>净光合速率>相对透性。玉米幼苗在渗透胁迫下具有一定的生理适应能力,表现在一定的渗透胁迫范围内随胁迫时间的延长,生长、生理变化有趋于缓和或恢复的趋势。     

玉米对渗透胁迫的反应和生理适应

利用不同渗透势的培养液模拟土壤干旱条件,研究了玉米杂交种“中单2号”在此条件下的生长和生理的变化。实验表明,各指标对于渗透胁迫的变化敏感性顺序为叶片延伸速率、叶水势、脯氨酸含量>净光合速率>相对透性。玉米幼苗在渗透胁迫下具有一定的生理适应能力,表现在一定的渗透胁迫范围内随胁迫时间的延长,生长、生理变化有趋于缓和或恢复的趋势。     

土壤干旱对黄土高原乡土树种水分代谢与渗透调节物质的影响

以黄土高原4个乡土树种的幼苗为试验材料,采用盆栽方式模拟土壤干旱环境,研究土壤干旱对不同树种水分代谢与渗透调节物质的影响。结果表明,大叶细裂槭、虎榛子叶水势、叶片含水量下降迅速,叶片离体保水能力降幅明显;白刺花、辽东栎则表现为叶水势、叶片含水量缓慢下降,组织相对含水量在中度胁迫下略有上升。白刺花在不同水分处理条件下离体叶片保水力明显高于其它树种。1个树种可溶性糖含量随土壤干旱程度加剧明显增加,可溶性蛋白质含量在树种之间变化较为复杂,无明显规律性。K^ 离子含量和游离脯氨酸含量在中度水分胁迫下均有不同程度升高。白刺花在土壤干旱进程中,可溶性蛋白质含量、K^ 离子含量和游离脯氨酸含量均明显高于其它树种。综合水分代谢和渗透调节物质来看,水分胁迫条件下,白刺花以保持高水势、减少组织水分散失和增加渗透调节物质来提高细胞原生质浓度,增强其抗旱性。     

冬小麦幼苗根系适应土壤干旱的生理学变化

采用盆栽试验对冬小麦幼苗根系适应土壤干旱的生理学变化进行了初步研究。结果表明，随干旱胁迫的加剧，洛麦9133和济麦21幼苗根水势、根相对含水率和根系活力均降低，饱和亏、可溶性糖含量、脯氨酸含量、质膜透性以及SOD、POD活性均呈增加趋势。这说明，在干旱胁迫下，冬小麦幼苗根系通过降低水势、相对含水率和根系活力，增加渗透调节物质可溶性糖、脯氨酸含量和增强SOD、POD活性等生理上的变化以提高抗旱性，从而使冬小麦幼苗适应干旱逆境。     

干热河谷9种造林树种在旱季的水分关系和气孔导度

 对元谋干热河谷人工混交林中9个树种叶片的水势、饱和渗透势、气孔导度、渗透调节和季节变化进行了测定,同时对树高和胸径也进行了比较。水分生理特征表明: 1)随着旱季的深入,除刺槐（Robinia pseudoacacia）、黄荆（Vitex negundo）、滇榄仁（Terminalia franchetii）落叶外,其余常绿树种叶片的气孔导度、水势和饱和渗透势都呈下降的趋势,在最旱的三、四月份,它们适应干旱的方式有4种：①低水势、气孔导度近似关闭的厚荚相思（Acacia leptocarpa）、大叶相思（A. auriculiformis）和肯氏相思（A. cunninghamii）;②低水势、低气孔导度的赤桉（Eucalyptus dulebsis）、娟毛相思（A. holosericea）和车桑子（Dodonaea wiscosa）loserice气孔导度的柠檬桉（Eucalyptus citriodora）和新银合欢（Leucaena leucocephala）;④较高水势、气孔导度近似关闭的马占相思（Acacia mangium）。2)在干旱胁迫过程中,主要渗透调节物质出现的先后顺序是K+、游离脯氨酸、游离氨基酸和可溶性糖, K+和可溶性糖贡献最大,分别在干旱的前后期起渗透调节作用,游离脯氨酸和游离氨基酸在干旱的中期起渗透调节作用。大多数树种适应干热河谷生境的主要抗旱途径是有效的吸水能力和完善的保水机制。     

外源乙醇胺对小麦幼苗某些抗逆生理指标的影响(简报)

在干旱胁迫条件下,经０．１％～１．０％乙醇胺处理的小麦幼苗叶片中,叶绿素含量和水势均增加,细胞的相对电导率降低,体内游离脯氨酸含量上升,幼苗株高和地上部鲜重增加。     

咸水浇灌后持续干旱条件下棉花生长及光合作用的变化

用咸水(不同浓度的NaCl溶液)浇灌盆栽棉花植株,随后进行持续干旱处理.测定干旱处理期间棉花的生长情况、光合速率、叶绿素荧光等参数的变化,并对植株的相对含水量、水势、渗透势等水分状况和Na⁺、K⁺含量进行分析,探索环境Na⁺在棉花适应干旱胁迫中的作用.结果表明: 干旱可以明显抑制植株的生长,降低叶片的净光合速率;用25～100 mmol·L^-1NaCl溶液浇灌后进行持续干旱处理的棉花植株,其株高、生物量、净光合速率和F_v/F_m值均明显高于用水浇灌后进行持续干旱处理的植株.同时,前者的土壤和叶片相对含水量、细胞膨压、Na⁺含量也明显高于后者,但植株水势和组织渗透势则显著低于后者,且组织渗透势的降低与Na⁺含量具有显著相关性.上述结果说明,土壤适量Na⁺的存在能够提高土壤和植株的保水力、增加棉花对Na⁺的吸收和积累、降低组织渗透势,从而增强植株吸水力、保持较高的细胞膨压,维持相对较高的光合速率和生长速度.土壤中存在一定浓度的NaCl可以有效缓解干旱对棉花的不利影响.     

Proline accumulation and nitrate reductase activity in contrasting sorghum lines during mid-season drought stress

Six lines of sorghum ( Sorghum bicolor L. Moench) with differing drought resistance (IS 22380, ICSV 213, IS 13441 and SPH 263, resistant and IS 12739 and IS 12744, susceptible) were grown under field conditions in the semi-arid tropics and analysed for proline and nitrate reductase activity (NRA; EC 1.6.6.1) during a mid-season drought. The resistant lines accumulated high levels of proline, while the susceptible lines showed no significant proline accumulation. Most of the proline was accumulated after growth of the plants had ceased. In a separate greenhouse experiment, most of the proline was found in the green rather than the fired portions of leaves. The levels returned to that of irrigated controls within 5 days of rewatering. Proline levels increased as leaf water potential and relative water content fell, and there was no apparent difference among the different sorghum lines with change in plant water status. Susceptible lines accumulated less proline than resistant lines as leaf death occurred at higher water potentials. Proline accumulation may, however, contribute to the immediate recovery of plants from drought. Leaf NRA reached high levels at about 35 days after sowing in both the stressed and irrigated plants, after which it declined. The decline in NRA was more pronounced in the stressed than in the irrigated plants and closely followed changes in the growth rate. Upon rewatering, NRA increased several-fold in all the lines and, in contrast to proline accumulation, genotypic differences in NRA were small, both during stress and upon rewatering. The high sensitivity of NRA to mild drought stress was reflected in the rapid decline of activity with small changes in leaf water potential and relative water content. The results are discussed in the light of a possible role for proline during recovery from drought, and the maintenance of NRA during stress and its recovery upon rewatering.     

干旱胁迫对持绿性高粱叶片渗透调节及叶绿体超微结构的影响

在盆栽条件下,研究了开花期和灌浆期干旱胁迫(土壤含水量为田间最大持水量的45%~50%)对持绿性高粱(B35)和非持绿性高粱(三尺三)叶片水分、渗透调节物质以及叶绿体超微结构的影响.结果表明: 干旱胁迫下,两高粱品系叶片自由水含量下降,束缚水含量增加,相对含水量降低,水分饱和亏缺增加,相对电导率增大,但三尺三各指标的变化幅度均大于B35.对于渗透调节物质,干旱胁迫下,三尺三可溶性糖含量的增幅大于B35,脯氨酸含量的增幅小于B35,可溶性蛋白含量的降幅大于B35.干旱胁迫下,B35与三尺三的叶绿体超微结构均受到一定程度的破坏,但B35叶绿体结构保持相对完好,受损程度明显小于三尺三.在干旱胁迫下,持绿性高粱通过较强的渗透调节表现出更好的干旱适应能力.
     

Effect of water stress on growth and proline metabolism of Phaseolus vulgaris L.

Summary The effect of water stress on growth (fresh weight, dry weight), water relations (water saturation deficit, water potential, osmotic pressure), and proline metabolism in Phaseolus vulgaris were studied.Experimentally, water deficit was produced by reduced watering of the bean plants. This resulted in a decrease in water potential and leaf fresh and dry weight. Increases in the water saturation deficit and the osmotic pressure of the sap were, however, recorded. Water stress was also induced by treatment of the plants with polyethylene glycol, but its effects on the above mentioned parameters were different. In addition, necrosis of the foliage was observed. According to the present results, polyethylene glycol seems to be suitable only for the induction of short-termed water stress conditions.The effects of water stress on growth and on water relations of the plants were accompanied by a marked increase in the free amino acid content, especially that of the free proline content of the plants. The activities of the proline dehydrogenase and glutamate dehydrogenase were stimulated under water stress conditions, indicating that proline accumulation in water stressed plants is not attributed to an inhibited proline breakdown. The accumulated proline was metabolized rapidly once the water deficit of the plant was relieved by watering. The ability of the plant to accumulate proline might be of ecological importance for the plant and might be an adaption mechanism of the plant to overcome short periods of drought.Abbreviations -Kg -ketoglutarate - GDH glutamate dehydrogenase - PDH proline dehydrogenase - P5C -pyrroline-5-carboxylic acid - PEG polyethylene glycol - WSD water saturation deficit     

Leaf extract of neem (Azadirachta indica) alleviates adverse effects of drought in quinoa (Chenopodium quinoa Willd.) plants through alterations in biochemical attributes and antioxidants

The influence of varying concentrations (0, 1, 3, 4, 5, 6, 8, and 10 % v/v) of neem (Azadirachta indica) leaf extract on drought stressed (40 % field capacity) quinoa (Chenopodium quinoa Willd.) plants was assessed. During the current study two cultivars of quinoa (V7 and V9) were used. This study revealed that water stress adversely affects the fresh and dry weight of shoots and roots as well as chlorophyll pigments (a and b) of both quinoa cultivars. In contrast, drought stress enhanced glycinebetaine (GB), free proline, phenolic content, hydrogen peroxide (H₂O₂), activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) enzymes, and relative membrane permeability (RMP). However, application of neem leaf extract improved the accumulation of key osmoprotectants like proline, GB and activities of enzymatic antioxidants. Our findings showed 5 % neem leaf extract is an effective treatment in counteracting the oxidative damage caused by water stress, thereby improving overall plant growth. Of both cultivars of quinoa, the response of cv. V9 to stress as well as foliar applied neem was relatively more promising.     

干旱胁迫下坡柳等幼苗质膜相对透性和脯氨酸含量的变化

以金沙江干热河谷主要树种坡柳、银合欢和山毛豆幼苗为材料,通过盆栽苗自然干旱胁迫,同时以浇水处理为对照,探讨了干旱胁迫下三树种幼苗叶片的相对含水量、质膜透性以及脯氨酸含量的变化情况。结果表明,干旱胁迫后三树种叶片的相对含水量、质膜相对透性以及脯氨酸含量都发生了变化,只是变化的幅度和进程不同。三项生理指标的综合分析及结合其自然表现,坡柳具有较强的抗旱能力,其次为银合欢,最后是山毛豆。     

Influence of exogenously applied paclobutrazol on some physiological traits and growth of Stevia rebaudiana under in vitro drought stress

This investigation was carried on to find out the changes occurred in Stevia rebaudiana in response to paclobutrazol (PBZ; 0–4 mg L^?1) treatment and drought stress. Polyethylene glycol (PEG; 0–6 % w/v) was used to stimulate drought stress. Drought stress reduced fresh and dry weight, water content, chlorophylls, carotenoids, anthocyanins, water soluble carbohydrates, reducing sugar and proline amounts. Electrolyte leakage, MDA, α-tocopherol and glycine betaine contents increased in drought-stressed plants. The activity of P5CS and PDH enzymes and protein content showed no significant changes under drought stress. PBZ (with or without PEG) treatments decreased fresh and dry weight and water content. In PBZ-treated plants, less pigments was damaged by drought stress. PBZ treatment reduced the negative effect of drought stress on lipid peroxidation which resulted in lower electrolyte leakage and MDA content, compared to the same PEG level without PBZ. PBZ (with or without PEG) treatments increased glycine betaine, α-tocopherol, proline and protein contents. The amount of water soluble carbohydrates, reducing sugar and activity of P5CS and PDH were not affected by PBZ treatments. SDS-PAGE analysis revealed that drought stress increased a 25 kD protein with a critical function in plant development under stresses. According to the results, PEG provoked a severe drought stress in S. rebaudiana that could partly be restored by PBZ treatment.     

Effect of Putrescine, 4-PU-30, and Abscisic Acid on Maize Plants Grown under Normal, Drought, and Rewatering Conditions

The experiments were carried out with maize (Zea mays L.) seedlings, hybrid Kneja 530, grown hydroponically in a growth chamber. Twelve-day-old plants were foliar treated with putrescine, N¹-(2-chloro-4-pyridyl)-N²-phenylurea (4-PU-30), and abscisic acid (ABA) at concentrations of 10⁻⁵ m. Twenty-four hours later the plants were subjected to a water deficit program, induced by 15% polyethylene glycol (PEG; molecular weight, 6,000). Three days after drought stress half of the plants were transferred to nutrient solution for the next 3 days. The effects of the water shortage, rewatering, and plant growth regulator (PGR) treatment on the fresh and dry weights, leaf pigment content, proline level, relative water content (RWC), transpiration rate, activities of catalase and guaiacol peroxidase, hydrogen peroxide content, and level of the products of lipid peroxidation were studied. It was established that the application of PGRs alleviated to some extent the plant damage provoked by PEG stress. At the end of the water shortage program the plants treated with these PGRs possessed higher fresh weight than drought-subjected control seedlings. It was found also that putrescine increased the dry weight of plants. Under drought, the RWC and transpiration rate of seedlings declined, but PGR treatment reduced these effects. The accumulation of free proline, malondialdehyde, and hydrogen peroxide was prevented in PGR-treated plants compared with the water stress control. The results provided further information about the influence of putrescine, 4-PU-30, and ABA on maize plants grown under normal, drought, and rewatering conditions. Received September 25, 1997; accepted August 10, 1998     

一氧化氮对水分胁迫下玉米种子萌发及幼苗生理特性的影响

以0.4mol/L的甘露醇(M)模拟水分胁迫状况,研究了外源一氧化氮(NO)供体硝普钠(SNP)对水分胁迫下玉米种子萌发、幼苗生长和生理特性的影响。结果表明:(1)水分胁迫下,玉米种子萌发和幼苗生长受到抑制,叶片丙二醛(MDA)含量、质膜相对透性、脯氨酸含量均显著增加;(2)SNP能显著提高水分胁迫下玉米种子的发芽率、发芽势、发芽指数和活力指数,增加玉米幼苗的根长、茎长、根重和整株干重,抑制水分胁迫下玉米幼苗叶片MDA含量的上升,降低叶片质膜相对透性,降低脯氨酸含量。其中以100μmol/L和200μmol/LSNP对水分胁迫的缓解效果最佳。     

Effects of Russian wheat aphid infestation on barley plant response to drought stress

The influence of Russian wheat aphid ( Diuraphis noxia Mordvilko) infestation on the response of barley ( Hordeum vulgare L. ev Hazen) plants to drought stress was investigated. Fourteen-day-old plants were infested with eight apterous adult aphids, which were removed 7 days later with systemic insecticide. Leaves previously infested with aphids had lower relative water content, reduced stomatal conductance, more negative water potential, lower levels of chlorophyll and higher levels of amino-N, proline and glycinebetaine than corresponding leaves from uninfested plants. When water was withheld for a period of 7 days after aphids were removed, the relative water content of previously infested plants dropped steadily from 0.89 to 0.60, while the relative water content of uninfested plants remained at about 0.94 for the first 4 days of the drought stress period followed by a steady drop to about 0.77 by the end of the drought stress period. Leaf water potentials dropped steadily during the drought stress period in both previously infested (-1.14 to -1.91 MPa) and unin-fested (-0.54 to -1.52 MPa) plants. Analysis of glycinebetaine and proline levels at the end of the drought stress period indicated that leaves of previously infested plants accumulated lower levels of these solutes than leaves from uninfested plants. Upon alleviation of drought stress, plants previously infested with aphids showed little increase in dry weight while younger leaves and tillers from uninfested plants showed large increases. It is concluded that Russian wheat aphids cause drought-stress symptoms in leaves of infested plants even in the presence of ample root moisture. The observations of low levels of glycinebetaine and proline present in leaves after water was withheld from roots and lack of leaf growth upon alleviation of drought stress in previously-infested plants, suggest that aphid infestation limits the capacity of barley plants to adjust successfully to drought stress.     

Effect of Drought Stress on Certain Morphological and Physiological Characteristics of a Resistant and a Sensitive Canola Cultivar

Water stress is one of the main abiotic factors that reduces plant growth, mainly due to high evaporative demand and low water availability. In order to evaluate the effects of drought stress on certain morphological and physiological characteristics of two canola cultivars, we conducted a factorial experiment based on a completely randomized design. The findings show that drought stress exacerbations result in the plant's response to stress due to increased canola resistance caused by changes in plant pigments, proline, catalase, ascorbate peroxidase, peroxidase, superoxide dismutase and malondialdehyde, glucose, galactose, rhamnose and xylose. These in turn ultimately influence the morphological characteristics of canola. Drought stress reduces the concentration of carotenoids, chlorophyll a, chlorophyll b, total chlorophylls; however, glucose, galactose, rhamnose, xylose, proline, catalase, ascorbate peroxidase, peroxidase, superoxide dismutase, malondialdehyde (in leaves and roots) and the chlorophyll a and b ratios were increased. Reduction of plant height, stem height, root length, fresh and dry weight of canola treated with 300 g/l PEG compared to non‐treatment were 0.264, 0.236, 0.394, 0.183 and 0.395, respectively. From the two canola cultivars, the morphological characteristics of the NIMA increased compared to the Ks7 cultivar. Interaction effects of cultivar and drought stress showed that NIMA cultivar without treatment had the highest number of morphological characteristics such as carotenoid concentration, chlorophyll a, chlorophyll b, total chlorophylls a and b, whereas the cultivar with 300 g/l PEG (drought stress) had the highest amount of proline, malondialdehyde, soluble sugars and enzymes in leaves and roots. Increasing activity of oxidative enzymes and soluble sugars in canola under drought stress could be a sign of their relative tolerance to drought stress.