镉对花生苗期的毒害效应及其品种间差异

重金属在籽粒中的积累与植物对镉的生物学耐性和吸收特性有一定的内在联系。本研究通过比较不同花生（Arachis hypogaea L.）品种对镉胁迫的生物学耐性,旨在为进一步揭示花生籽粒镉积累的种内差异形成机制提供实验参数。在人工气候箱控制环境下的含镉的营养液砂培试验中,花生苗期对镉胁迫的反应具有显著的品种间遗传差异。基于植株生物量变化,可将花生的镉胁迫反应分为3种类型,即镉钝感型,品种有平度01、花育23和莱农13;敏感型,品种有中花4号、花育20、丰花3号、莱农29、豫花15和祁阳小籽;普通型,品种有湘农3010-w、湘农312、湘农55、丰花2号和湘农小果w2-7等。钝感型品种在5个加Cd水平下的茎叶干物量比对照平均降低22.8%,全株生物量平均降低11.7%;敏感型品种茎叶干物量平均降低38.0%,全株生物量降低29.2%;普通型品种茎叶干物量平均降低33.2%,全株生物量降低25.1%。随着Cd质量浓度提高和暴露时间延长,花生叶片的叶绿素质量分数显著降低,叶片和根系丙二醛质量分数及细胞膜透性显著提高,与钝感型品种相比,敏感型品种的上述生理指标变化速率较高,而且随着镉暴露时间延长,两者之间的差异性持续扩大。

Toxic effect of Cd on peanut seedlings and the intra-specific variations

Heavy metal accumulation in crop grains has certain internal relations with its bio-tolerance and capacity of root uptake.Comparing the biological tolerance to cadmium stress of different peanut（Arachis hypogaea L.）varieties,the study is designed to further reveal the formation mechanism of intra-specific differences of cadmium accumulation in peanut grains.Sand-based nutrient solution cultivation experiment under controlled growth environment by artificial climate chamber found that there was a significant intra-specific variation in the biological responses of peanut plants on cadmium stress.According to the assignment of biomass de-clining rate（i.e.the slope）of peanut shoots and roots toward with increase of Cd concentration of the solution,the Cd-tolerance of peanut varieties could be classified into three types：the insensitive type,including varieties of Pingdu-01,Huayu-23 and Lainong-13;the sensitive type,including Zhonghua-4,Huayu-20,Fenghua-3,Lainong-29,Yuhua-15 and Qiyangxiaozi;the general type,includ-ing Xiangnong-3010-w,Xiangnong-312,Xiangnong-55,Fenghua-2 and Xiangnongxiaoguo-w2-7.Compared with the control,the shoot and whole plant biomass（dry weight）of the insensitive varieties was decreased by 22.8% and 11.7% on average under the five levels of Cd added treatments,respectively.While the one of sensitive varieties was reduced by 38.0% and 29.2 %,the one of general varieties was reduced by 33.2% and 25.1%,respectively.With increase of Cd concentration in the solution and prolongation of the exposure time,the content of chlorophyll in peanut leaf decreased significantly,leaf and root MDA contents and membrane perme-ability increased significantly.Compared with the insensitive cultivar,rate of the above physiological changes of the sensitive variety was significantly fast,and with prolongation of the exposure time,differences of the indexes between the two kinds of varieties be-came bigger and bigger.