红壤旱地稻草覆盖对夏玉米抗旱性的影响

为了探明不同稻草覆盖量对红壤夏玉米地抗旱性的影响, 2006-2012年, 以不覆盖为对照(CK), 在中国科学院桃源农业生态试验站设置 3 个水平稻草覆盖量: 5 000 kg·hm^-2 (T1)、10 000 kg·hm^-2 (T2)和15 000 kg·hm^-2 (T3), 调查各处理的土壤水分、夏玉米生长和光合性能, 以及玉米产量与干旱程度的相关性。结果表明, 稻草覆盖提高表层土壤(0~20 cm)总有效水含量, T1、T2、T3与CK相比分别提高6.8%、19.3%(P>0.05)和28.4%(P<0.05)。光合速率灌浆期T1、T2、T3比CK分别提高24.1%、40.3%、53.8%, 成熟期分别提高20.0%、40.3%、37.9%。研究发现, 生育期旬干旱发生比率为18.2%, 覆盖处理与对照之间产量无显著差异; 发生比率为18.2%~63.6%时, 玉米产量差异显著(P<0.05); 发生比率为18.2%~36.4%时, T1产量最大, 而在54.5%时, T3产量最大; 2011年发生比率为63.6%, 超出了稻草覆盖抗旱范围。综合考虑稻草利用效率和平均抗旱能力, 本研究建议在红壤丘陵区旱地5 000 kg·hm^-2的稻麦覆盖量较适宜。

Effect of straw mulching on drought resistance of summer maize in upland red soils

An upland red soil experiment was conducted from 2006 to 2012 to determine the effects of rice straw mulching on seasonal drought resistance of summer maize. The study was conducted at the Taoyuan Agro-ecological Experimental Station of Chinese Academy of Sciences, Hunan Province, China. Rice straw was applied at the rates of 0 (CK), 5 000 kg·hm^-2 (T1), 10 000 kg·hm^-2 (T2) and 15 000 kg·hm^-2 (T3) in field plots. The results showed that compared with CK (control), total soil available moisture in T1, T2 and T3 increased by 6.8% (P > 0.05), 19.3% (P > 0.05) and 28.4% (P < 0.05), respectively. In 2012, maize photosynthetic rate at filling stages in T1, T2 and T3 respectively increased by 24.1%, 40.3% and 53.8%. Also T1, T2 and T3 were respectively higher in photosynthetic rate than CK by 20.0%, 40.3% and 37.9% at maturity stage. At drought occurrence rate of 18.2% per ten days, there was no significant difference in maize yield between rice straw mulching and CK. Yield difference was significant (P < 0.05) when drought occurrence rate was 18.2% 63.6% per ten days. When drought occurrence rate was 18.2% 36.4% per ten days, T1 had the maximum yield. When drought occurrence rate reached 54.5% per ten days, T3 produced the maximum yield. When drought occurrence rate exceeded 63.6% per ten day, rice straw mulching was no longer suitable for resisting drought. The recommended amount of straw mulch in the southern hilly red soils was 5 000 kg·hm^-2.