玉米耐低温冷害研究进展

玉米是典型的喜温C4作物,低温冷害胁迫是影响玉米生产的重要非生物逆境因素。为了研究低温对玉米生长发育的影响,归纳了玉米在低温胁迫条件下生理生化指标、光合作用参数的变化及耐冷遗传机制等方面的研究进展,并介绍了国内外抵御低温冷害所采取的方法,探讨了玉米耐低温研究的方向,提出玉米耐低温研究应更加注重玉米耐冷种质资源的创新及耐冷基因的挖掘利用。     

热处理对青椒冷害的影响及作用机理的研究

以新鲜青椒为试验材料,研究热处理抑制贮藏期间青椒冷害的发生和机理.采用37℃热处理24 h,对照为20℃,然后在0℃条件下贮藏;对贮藏过程中冷害发生及与冷害的发生相关的细胞膜渗透率、丙二醛含量、叶绿素含量以及自由基清除剂超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性的变化趋势进行了研究.结果表明,37℃热处理可以减轻青椒低温贮藏冷害发生,延缓细胞膜渗透率的上升和丙二醛(MDA)的积累,延缓叶绿素含量的下降,提高膜脂过氧化保护酶POD、SOD、CAT活性,保护膜的稳定性.     

Effect of Low Soil Temperature on Weight Increase, Gas Exchange and Distribution of 14C-Assimilates in Seedlings of a Maize Hybrid

Seedlings of a maize hybrid sensitive to chilling initially grew in the growth chamber of the phytotron at 20/ 17°C (day/night) and after the formation of the fourth leaf, the soil temperature was lowered to 5°C. Under such growth conditions the dynamics of dry weight change, gas exchange and the distribution of ¹⁴C-assimilates in seedlings were examined. The low soil temperature inhibited daily growth of dry weight of whole seedlings more than their photosynthesis. Simultaneously, it was also responsible for a greater increase in dissimilative losses.
During 37 hours (day-night-day), following exposure to ¹⁴CO₂, dissimilation in seedlings in cool soil (5°C) and in non-chilling conditions amounted to 35.1 % and 23.4 % of assimilated ¹⁴C (AC), respectively. At lower soil temperature relatively high dissimilative losses were observed on the first day after exposure (23.5 %), lower at night (9.9 %) and the lowest on the following day - merely 1.7 % AC. Higher losses of ¹⁴C under chilling conditions occurring on the first day were a result of limited photosynthetic refixation of ¹⁴CO₂ At night, however, they were associated with a prolonged period of intensive translocation of assimilates to the stem. It was assumed that an excessive accumulation of assimilates in leaf blades might be an additional factor responsible for increased dissimilative losses at low temperature during the first twenty-four hours. In the third period of measurements, as a result of a limited transport of ¹⁴C, dissimilative losses were lower than in previous ones and were not dependent upon soil temperature.     

Effect of Low Night Temperatures on Photosynthetic Activity of the Maize Seedlings (Zea mays L.)

Night chilling (5 °C) subsequently lowered photosynthetic intensity in the leaves of maize seedlings at 20 °C through an increase in leaf diffusive resistance brought on by lower tissue water content in morning hours. A more significant increase in leaf diffusion resistance was observed when soil temperature was lowered than in the case of lower air temperature.
The unfavorable effect of soil and air cooling temperature on photosynthesis was limited by air saturated with water vapour. However, as a result of lowering the night temperature from 5 °C to 1 °C, the efficiency of the protective influence of higher atmospheric humidity was decreased. This demonstrates that the participation of factors unrelated to plant water status in inhibiting photosynthesis increases with lower night temperatures.
An additional reason for inhibited photosynthesis following cool nights was a decrease in chlorophyll accumulation, below 50 μg per 1 cm² of leaf area.     

Exploring the Role of Calcium to Improve Chilling Tolerance in Hybrid Maize

Abiotic stresses, including chilling, impede the plant growth and development mainly by oxidative damage. In this study, seed priming with CaCl₂ was employed to reduce the damage caused by chilling stress in hybrid maize. Maize hybrid (Hycorn 8288) seeds were soaked in 50, 100 and 150 mg l⁻¹ (ppm) aerated solution of CaCl₂ for 24 h and dried. Treated and untreated seeds were sown at 27 °C (optimal temperature) and 15 °C (chilling stress) under controlled conditions. Seed priming with CaCl₂ significantly reduced the chilling damage and improved the germination rate, root and shoot length, and seedling fresh and dry weights. Activities of antioxidants, including catalase, superoxide dismutase and ascorbate peroxidase, were also improved. Soluble sugars and α-amylase concentrations determined as general metabolic indicators of stress were also increased by seed priming with CaCl₂. Priming also improved the performance of maize at optimal temperature. Maintenance of tissue water contents, reduction in membrane leakage and increase in antioxidant activities, and carbohydrate metabolism seemed to induce chilling tolerance by CaCl₂. Seed priming with 100 mg l⁻¹ CaCl₂ was the optimal concentration in improving the performance of hybrid maize both under optimal and stress conditions.     

高浓度镍对水稻幼苗生长及酶活性的影响

0.8、1.2、2.0mmol/L的Ni2+处理,水稻幼苗的生长表现出明显的阻滞现象,提示此浓度范围的Ni2+已对水稻幼苗产生了毒害.同时,水稻幼苗叶片超氧化物歧化酶(SOD)、过氧化氢酶(CAT)及抗坏血酸过氧化物酶(APX)的活性降低,H2O2和丙二醛(MDA)含量明显增多,而过氧化物酶(POD)活性却升高.统计分析表明,H2O2与MDA含量成显著正相关,而MDA     

外源ABA和6-BA对不同持绿型小麦旗叶衰老的影响及其生理机制

为深入认识植物激素在小麦抗氧化和调控衰老中的作用机制,以持绿品种汶农6号和非持绿品种济麦20为材料,在盛花期后喷施脱落酸(ABA)和6-苄基腺嘌呤(6-BA),考察外源激素对旗叶衰老过程中生理生化指标动态变化以及籽粒产量的影响,并探讨了激素与衰老的关系。结果表明,汶农6号旗叶的超氧化物歧化酶(SOD)和过氧化物酶(POD)活性、叶绿素含量及籽粒千粒重和产量均大于济麦20,且丙二醛(MDA)含量低于济麦20,表明持绿型品种抗氧化能力强,衰老进程较慢,进而获得较高产量。外源ABA和6-BA处理显著提高花后7~28 d旗叶叶绿素含量,提高花后21~35 d可溶性蛋白含量,显著降低花后28~35 d旗叶MDA含量。外源ABA降低两品种旗叶玉米素(ZR)含量,但提高生长素(IAA)和赤霉素(GA)含量,降低了其在花后28~35 d的ABA含量。6-BA处理提高旗叶ZR含量及花后7~14 d IAA含量,降低济麦20花后21~35 d旗叶ABA含量。外源ABA显著提高汶农6号花后7~21 d旗叶SOD活性,喷施ABA对汶农6号旗叶POD和过氧化氢酶(CAT)活性影响没有显著性影响,但显著提高了济麦20花后7~28 d POD活性,喷施6-BA提高了两品种7~28 d SOD、POD和CAT活性。总之,ABA和6-BA处理改变了旗叶内源激素水平,提高抗氧化酶活性,降低MDA含量,延缓旗叶衰老,从而提高了籽粒产量。     

镉胁迫对莴苣种子萌发及抗氧化酶系统的影响

以笋王一号莴苣为试验材料,研究了不同浓度Cd胁迫对莴苣种子萌发、胚根胚芽生长、丙二醛(MDA)及抗氧化酶系统的影响.结果表明:随着Cd浓度的增加,莴苣种子的发芽率逐渐降低,而Cd对种子的发芽势、发芽指数和活力指数以及胚根的伸长则表现出低促高抑的效应.Cd对胚根生长的抑制程度较胚芽明显.随着Cd浓度的增加.胚根中MDA含量、SOD、G-POD活性明显增加,APX和CAT活性则明显降低,而胚芽中只在高浓度Cd胁迫下(100μmol/L)才发生明显变化.     

不同品种藜麦苗期对海拔变化的生理响应

为研究不同品种藜麦幼苗对海拔梯度变化的生理响应机制,本试验以4个藜麦品种—‘陇藜1号’、‘陇藜2号’、‘陇藜3号’及‘陇藜4号’为材料,选取甘南州临潭县3个不同海拔(2 380 m,2 580 m,2 780 m)分布区为试验地.通过测定幼苗生物量及生理生化指标,分析不同藜麦品种幼苗在不同海拔试验区的生理响应机制,为建...     

不同品种青贮玉米群体光合性能指标的变化

通过对不同青贮玉米品种群体光合性能指标的研究结果表明,不同青贮玉米品种叶面积指数、光合势、群体生长率在整个生育期均呈单峰曲线变化,峰值出现在散粉至乳熟期间,因不同品种而异。净同化率则呈“马鞍”型曲线变化。多分蘖品种科试1号、植株高大品种东陵白与农大647在生育期间叶面积指数和光合势均较高,东陵白生育前、中期群体生长率显著高于其它品种,且高值持续时间较长,这是其生物产量高的生理基础。生产中,采取合理栽培措施,克服此类品种植株高大、个体繁茂、群体郁蔽导致植株病害和倒伏严重的不足,可实现青贮玉米群体生物产量的进一步提高。     

不同覆膜栽培方式对玉米光合特性及产量形成的影响

为探索山西晋中地区获得玉米高产稳产的适宜覆膜种植方式,在大田试验条件下研究了4种覆膜方式对玉米叶面积指数、光合速率、蒸腾速率、气孔导度、叶片水分利用效率及籽粒产量的影响。结果表明：与对照相比,不同覆膜栽培方式均可显著提高叶面积指数、净光合速率、气孔导度和叶片水分利用效率,可显著提高花后叶片的蒸腾速率,从而显著提高产量。其中,起垄膜侧种植方式处理的光合特性最佳,产量最高,较对照提高36.2%。籽粒产量与穗行数呈显著正相关,与穗长、行粒数及百粒重呈极显著正相关;抽穗期、灌浆期和成熟期光合参数与籽粒产量的相关性略高于拔节期和大喇叭口期,说明通过提升花后的光合作用能够更有效地提高作物产量。总之,起垄膜侧种植栽培方式有利于玉米提高光合特性和籽粒产量,是一种适合晋中地区玉米生产的覆膜方式。     

Electrolyte Leakage, ATP Content in Leaves and Intensity of Net Photosynthesis in Maize Seedlings at Permanent or Different Daily Exposure to Low Temperatures

Changes were determined in electrolyte leakage (EL), ATP content in leaves and intensity of net photosynthesis (FJ in maize seedlings as a result of continued exposure to low temperatures for several days or, after a cold night (5 °C, 9 h), alternating application of 5 °C and 20 °C temperatures during the lit phase of the day (h of chilling during day/night: 0/9, 5/9, 10/9, 15/9).
At continuous exposure to low temperatures, permanent reduction of ATP content occurred between days 7 and 10, while EL increased significantly between days 4 to 7 (depending on experimental conditions). Of three leaves differing in age, most injuries were found in the oldest leaf. An increased intensity of irradiation from 150 to 500 μE. m⁻².s⁻¹ caused an earlier decrease in the ATP content and a further increase in electrolyte leakage. ATP content showed a 24 h rhythm, it increased at the end of the night and decreased at the end of the day. The rhythm was particularly noticeable in the control plants (20 °C), as well as, however to a lesser extent, in plants exposed to daily fluctuating chilling temperatures. It has also been observed that higher temperatures occurring in day time may diminish electrolyte leakage induced by previous low temperatures
The intensity of F_n determined at 20 °C, 4 h after withdrawal of chilling, decreased with the prolongation of the chilling period during the day.
Thus, it may be assumed that the EL and F_n values as indicators of the plants' sensitivity are in better agreement with the induced chill doses than the ATP content in leaves, which to a greater extent depends on the interaction between chilling and other experimental factors, such as irradiation intensity or the sequence of light and darkness.     

菘蓝试管苗玻璃化过程中抗氧化物酶活性的变化

为明确植物体内抗氧化酶活性变化与组培玻璃苗发生的关系,以菘蓝(Isatis indigotica Fort.)正常试管苗和玻璃苗为研究材料,对其抗氧化物酶活性和膜脂质过氧化水平进行了比较分析.结果表明:正常苗和玻璃苗中过氧化物酶(POD)活性随培养时间的延长先降低后升高,过氧化氢酶(CAT)活性先升高后降低,过氧化物歧化酶(SoD)活性和丙二醛(MDA)含量始终呈上升趋势.同一培养时期,玻璃苗中CAT、SOD活性均低于正常苗,而MDA水平远远高于正常苗.表明组培过程中有氧自由基的胁迫,而玻璃苗细胞内保护酶的调节功能紊乱,从而发生了更严重的脂质过氧化.此外,与正常苗相比,玻璃苗中POD同工酶电泳谱带出现增加、缺失等异常现象,表明玻璃苗中酶的表达失常,遗传稳定性改变.     

新疆野苹果幼苗对盐胁迫的生理响应

为了解新疆野苹果盐胁迫下的生理特性,以新疆野苹果实生幼苗为试材,设置6个Na Cl梯度(0,0.2%,0.4%,0.6%,0.8%,1.0%)处理4 h和0.4%Na Cl溶液处理7个时间梯度(0,4,8,12,16,20,24 h),采样测定其叶片中脯氨酸(Pro)、丙二醛(MDA)、叶绿素(Chl)和可溶性糖含量以及超氧化物歧化酶(SOD)和过氧化物酶(POD)活性的变化。结果表明:叶片中脯氨酸的含量在Na Cl浓度为0.6%时和Na Cl浓度为0.4%处理12 h时,达到峰值,分别比对照提高了63.1%和27.0%。随着盐浓度的升高和盐胁迫时间的延长,丙二醛的含量呈现出逐渐增加的趋势。叶绿素变化呈现出先降低后升高再降低的趋势,所有处理中,叶绿素含量均低于正常水平。可溶性糖含量、SOD和POD的活性均呈现先上升到达峰值后再下降的趋势。新疆野苹果幼苗在盐胁迫下可通过积累脯氨酸和可溶性糖,提高SOD和POD的活性,以减缓盐胁迫对植株的伤害且具有一定的耐盐性。     

两种生态型黄瓜幼苗光系统I抗氧化酶对弱光的响应

以2种生态型黄瓜品种为材料,在人工气候室内,研究了弱光对光系统I(PSI)水-水循环电子传递过程中一系列酶活性的影响,以期了解黄瓜苗期弱光响应的生理机制。结果表明,在弱光胁迫的早期,超氧化物歧化酶(SOD)、抗坏血酸过氧化氢酶(APX)和脱氢抗坏血酸还原酶(DHAR)活性比对照有所增加,但随着黄瓜幼苗对弱光的不断适应,3种酶活性逐渐降低。此时,耐弱光型品种(S1)叶片中的SOD、APX和DHAR活性增幅要明显高于S404,而单脱氢抗坏血酸还原酶(MDHAR)和谷胱甘肽还原酶(GR)活性在两供试材料中与对照相比均有所减弱。弱光下,S1叶片中MDHAR活性高于S404,而GR活性却低于S404。因此,耐弱光型黄瓜品种具有较高地清除活性氧和自由基的能力,可能通过调节NADPH在PS I水-水循环电子传递链中的分配来更好地适应弱光逆境。