Abstract:

Peanut is one of the ideal crops in dry farming. Drought is the main limit factor of peanut to increase yield and improve quality. Seedling stage is constantly hit by drought for summer peanut. In order to understand the suitable watering amount at peanut seedling stage, provide theoretical basis and technique for dry farming peanut producing the experiment was conducted with drought light-resistant peanut cv. Luhua 11 and drought resistant peanut cv. Nongda 818 from 2003 to 2004 in the experimental station of Shandong Agricultural University. Five treatments with watering 20 mm(serious drought stress), 40 mm(middle drought stress), 60 mm(slight-middle drought stress), 80 mm(slight drought stress) and 100 mm(CK) were made at 10 days after seedling(27 June) with three replicates in a randomized block design. The drought stress stopped at full-bloom stage(20 July) and then all treatments were irrigated 100 mm water at full-bloom stage, pod setting stage and pod filling stage separately. The results showed that the photosynthesis rate(P_n) decreased, and malondialdeyde (MDA) content increased remarkably with the drought degree raising. After rewatering, the MDA content decreased and Pn returned to the level of check rapidly, the recovery ability of Nongda 818 was bigger than that of Luhua 11. Suitable drought treatment could enhance the activities of superoxide dismutase(SOD), peroxidase (POD) and catalase (CAT), and increase the soluble protein content. The highest activities of SOD, POD, CAT and soluble protein content presented at the slight-middle drought treatment(watering 60–80 mm ) for Luhua 11, but at the middle drought treatment(watering 40–60 mm ) for Nongda 818. At the same drought treatment, especially at serious drought treatment(watering 20 mm), the activities of SOD, POD, CAT of Nongda 818 were obviously higher than that of Luhua 11. After rewatering, the activities of SOD, POD, CAT and soluble protein content reduced significantly, but the activities of SOD, POD, CAT of Nongda 818 were still higher than that of Luhua 11. With the drought degree raising, pod and kernel yields substantially decreased and the yield losses of Nongda 818 were less than that of Luhua 11. The irrigating amount at peanut seedling stage is no less than 60–80 mm to avoid the yield loss. Middle and slight drought stress at seedling stage could increase the protein content of peanut kernel, and have a little effect on fat content. Serious drought stress at seedling stage remarkably decreased oleic content and the ratio of oleic/linoleic(O/L), increased linoleic content of peanut kernel, and have a little effect on protein content. The optimal irrigating amount at seedling stage for the best kernel quality of Luhua 11 is 60–80 mm and that of Nongda 818 is 40–60 mm.

Key words: Peanut, Drought at seedling stage, Physiological traits, Yield and quality