叶面喷施外源多胺提高夏玉米灌浆前期抗涝性

为缓解玉米涝渍胁迫危害,该研究在夏玉米灌浆前期设置3、5、7、9 d的测坑淹水试验,分析淹水及淹水后叶面喷施外源多胺对夏玉米叶片可溶性糖、根系活力、地上部干物质、内源亚精胺、籽粒质量动态变化和产量的影响。结果表明:淹水后与CK相比,淹水5、7、9 d叶片可溶性糖含量下降,地上部干物质质量均显著减少,淹水3、7、9 d百粒质量增加,5 d减少,籽粒质量、穗行数、行粒数、产量均显著降低。叶面喷施外源多胺后,相同淹水天数处理间比较,淹水5、7、9 d叶片可溶性糖含量增加、根系活力增强,淹水7、9 d叶片内源亚精胺含量增加,淹水5 d百粒质量显著增加,淹水3、5 d植株行粒数分别增加8.24%和7.41%,产量分别提高7.92%、5.85%(P0.05)。因此,夏玉米灌浆前期遭遇淹水后5 d内叶面喷施外源多胺,能够提高其抗涝性,减少产量损失。

Foliar spraying polyamine improving waterlogging resistance of summer maize in early grain filling stage

Exogenous polyamine is a type of bioregulators and often used for drought resistance. This study investigated the feasibility to use it for waterlogging resistance in summer maize. A test-pit experiment was carried out in Shang qiu, China (24°35′N, 115°34′E, elevation 50.2 m). The waterlogging treatments for 3, 5, 7 and 9 days were designed in early grain filling stage of summer maize. At 3 days before ending waterlogging, the exogenous polyamine solutions or equivalent distilled water were sprayed 2 times per day (at 8:00 a.m. and 18:00 p.m.) to the maize in each treatment, respectively. Meanwhile, the field without waterlogging was set up as the control (CK). Samples were taken at 3, 6, 9 and 12 days after spraying for determination of soluble sugar content of leaves, root activity, shoot dry biomass, and endogenous spermidine content of leaves. At harvest, grain weight, yield and its components were measured. The results showed that: 1) After waterlogging in the early grain filling stage of summer maize, the soluble sugar content of leaves decreased. Spraying exogenous polyamine greatly increased the soluble sugar content. At 3 days after waterlogging, compared with distilled water treatment, the exogenous polyamine treatments for 3, 5, 7 and 9 days waterlogging significantly increased the soluble sugar content by 12.13%, 8.36%, 20.01%, and 12.17%, respectively (P<0.05); 2) At 3 days after waterlogging, compared with the distilled water treatments, the root activity for exogenous polyamine treatments in 3, 5, 7 and 9 days waterlogging was significantly increased by 24.76%, 40.45% and 31.46%, respectively (P<0.05). Overall, the root activity presented a upward-to-downward trend after the waterlogging; 3) The shoot dry biomass, spike length, rows per spike, kernels per row and yield of all the treatments were reduced significantly (P<0.05) compared to the CK. The spike core weight of 5 and 7 days of water flooding treatments decreased significantly (P<0.05), while there weren't significantly different at 3 and 9 days of water flooding treatment. The hundred-grain weight of 3, 7, and 9 days of water flooding treatment increased significantly (P<0.05), while dropped significantly after 5 days of waterlogging treatment. For the 3 and 5 days of waterlogging treatments, compared with treatments with distilled water, spraying exogenous polyamine increased the spike length by 6.56% and 7.80%, respectively, increased the rows per spike by 8.24% and 7.41%, respectively, and the increased the yield by 7.92% and 5.85%, respectively (P<0.05). In general, spraying exogenous polyamine was effective for waterlogging resistance in the early grain filling stage of summer maize when waterlogging lasted for 5 days or less, but the effect was not obvious for 7-9 days of waterlogging. In the future, different spraying amount and concentrations should be explored in order to find an optimal spraying amount and concentration. This study could provide useful information forthe recovery of summer maize after waterlogging.