Shubo Wan

Identification and Evaluation of Drought Resistance in Different Peanut Varie-ties Widely Grown in Northern China

It is necessary to systematically identify and evaluate drought-resistant varieties for stable development of peanut pro- duction in arid and semi-arid regions in northern China. To establish drought resistance index of peanut varieties, we determined 13 morphological and biochemical indices including plant height, number of branch, biomass, leaf water content and photosyn- thetic pigment content in the pot experiment at pod setting and pod filling stages with 29 peanut varieties (lines) widely grown in north China under artificial water stress condition. Drought resistances of varieties were scored with drought coefficient method and subordinate function value under water stresses. The results showed that the same index of drought resistance characterized in different peanut varieties achieved different results, and 29 peanut varieties were divided into four grads: high tolerant, moderate tolerant, weaker tolerant, and drought susceptible. In the 29 varieties (lines), we screened out the high drought tolerant varieties consisting of Tangke 8, Jihua 2, Jihua 4, Huayu 25, Huayu 17, Huayu 22, Datangyou, and Huayu 21. The varieties (lines) of Huayu 20, Huayu 24, Weihua 6, Huayu 27, Luhua 11, Fuhua 11, Fuhua 13, Tangyou 4, Fenghua 1, and G2 had moderate drought resistance. The varieties (lines) with weaker drought resistance were 16-8, Fuhua 10, M5, Huayu 16, and Luhua 14. At pod setting and pod filling stages Huayu 19, Huayu 23, Fenghua 6, Weihua 8, M7, and TE-2 were all drought susceptible. From seedling to pod setting stages under water stress, all morphological and biochemical indices but the number of branch and carotenoid content and their comprehensive D-values could be taken as evaluation criteria. From seedling to pod filling stages under water stress, there only existed significanct correlation between leaf area and drought resistance. Either at pod setting or pod filling stages un- der water stress, comprehensive D-value of the indices had significant correlation with drought resistance, which could be used to identify peanuts drought resistance.

Effect of Drought Stresses at Different Growth Stages on Peanut Leaf Protective Enzyme Activities and Osmoregulation Substances Content

Using Huayu 22 and Huayu 25 as experimental materials, the physiological and biochemical parameters at seedling stage, flowering-pining stage, and podding stage in peanut leaf were investigated under drought stress in pool cultivation with rainproof. The result showed that, the changes of antioxidant systems and the components of osmoregulation substances of two varieties were not entirely consistent during early drought stress stage. Leaf superoxide dismutase (SOD) and catalase (CAT) activities, soluble protein (Pr), free amino acid (AA) and proline (Pro) contents were significantly increased and then decreased under drought stress. With the prolonged stress, the protective enzyme activities and osmoregulation substances content decreased at the same time. The POD activity and soluble sugar content weakly responded to drought stress. The content of malondialdehyde (MDA) was significantly increased and then decreased with the stress prolonged, but its time lagged behind those of the protective enzyme activities. The MDA content in Huayu 22 leaf was higher than that in Huayu 25. After the drought stress, the activities of SOD, CAT, and soluble protein, free amino acid and proline contents were obviously increased at the end of drought stress at different growth stages. Among those stages, all the parameters were markedly increased at the flowering-pining stage, which is sensitive to water supply. The effects of drought stress on protective enzyme activities and osmoregulation substances of peanuts were weaker at seedling stage than at late growth stages. SOD and CAT were the key antioxidant enzymes to adapt dr ought stress in peanut. The ability of osmoregulation substances contributed to the regulation of drought stress in turn was: soluble sucrose free amino acid soluble protein proline. The drought tolerance of Huayu 25 was higher than that of Huayu 22.