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In order to explore the difference on the resistance physiology and yield and the mitigation effect of uniconazole (S3307) pretreatment under waterlogging stress, the pot experiment was conducted using Longxiaodou 4 (LXD 4) and Tianjinhong (TJH). The anti-stress physiological indexes and yield were measured on 5th day after waterlogging stress and foliar spraying S3307 at seedling stage, and samples were taken every day. The results showed that leaf physiological indexes in waterlogging stress were changed during seedling stage, the content of H 2 O 2 , MDA, proline and soluble protein were significantly increased, as the same as the content of ABA, IAA, and SA, and the activities of SOD, POD, and CAT. Waterlogging treatment for five days resulted in a significant decrease in the output of LXD 4 in a single pot by 8.40% to 12.61%, and that of TJH decreased by 9.91% to 10.01%. S3307 had the effect of resisting waterlogging stress, and could effectively increase the content of proline and soluble protein in the leaf of adzuki bean, significantly reduced the content of H 2 O 2 and MDA, significantly increased the activity of SOD and POD, the value of SOD/POD and SOD/CAT, significantly increased the ABA and SA content, and significantly inhibited the increase in IAA content. Foliar spraying S3307 significantly increased the output of LXD 4 by 2.85% to 6.18% under waterlog-第 3 期 项洪涛等: 幼苗期淹水胁迫及喷施烯效唑对小豆生理和产量的影响 495 ging treatment for four days, and significantly increased the yield of TJH by 2.85% to 3.95%, respectively. This study concluded that there were significant differences under physiological stress in reactive oxygen species accumulation, membrane lipid peroxidation, antioxidant enzyme activities and hormone levels among different varieties of adzuki bean under waterlogging stress. Spraying S3307 could effectively alleviate the effects of waterlogging stress on the physiology and yield in adzuki bean. The results provide a theoretical basis for further studying the physiological mechanism of adzuki bean resistance to waterlogging at the seedling stage and improving the yield of adzuki bean under waterlogging stress.

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Application of plant growth regulators (PGRs) to soybean plants is known to induce changes in nitrogenase activity in root nodules, and this led us to hypothesize that PGRs would affect nitrogenase activity in free-living rhizobia cultures. Little is known about the molecular basis of the effects of PGRs on nitrogenase activity in free-living rhizobia cultures. Therefore, a comparative study was conducted on the effects of gibberellins (GA 3 ) and mepiquat chloride (PIX), which regulate plant growth, on the nitrogenase activity of the nitrogen-fixing bacterium Bradyrhizobium japonicum. Fix and nif gene regulation and protein expression in free-living cultures of B. japonicum were investigated using real-time PCR and twodimensional electrophoresis after treatment with GA 3 or PIX. GA 3 treatment decreased nitrogenase activity and the relative expression of nifA, nifH, and fixA genes, but these effects were reversed by PIX treatment. As expected, several proteins involved in nitrogenase synthesis were down-regulated in the GA 3 -treated group. Conversely, several proteins involved in nitrogenase synthesis were upregulated in the PIX-treated group, including bifunctional ornithine acetyltransferase/N-acetylglutamate synthase, transaldolase, ubiquinol-cytochrome C reductase iron-sulfur subunit, electron transfer flavoprotein subunit beta, and acyl-CoA dehydrogenase. Two-pot experiments were conducted to evaluate the effects of GA 3 and PIX on nodulation and nitrogenase activity in Rhizobium-treated legumes. Interestingly, GA 3 treatment increased nodulation and depressed nitrogenase activity, but PIX treatment decreased nodulation and enhanced nitrogenase activity. Our data show that the nif and fix genes, as well as several proteins involved in nitrogenase synthesis, are up-regulated by PIX and down-regulated by GA 3 , respectively, in B. japonicum.