低磷营养胁迫下水稻化感抑草潜力的变化特性及其作用机理

在低磷(0.5 mg·L^-1) 营养胁迫下,运用生理生化方法分析了化感水稻PI312777（PI）与非化感水稻Lemont (Le) 对稗草抑制作用潜力的变化特性及其内在机理.结果表明，在低磷营养胁迫下，化感水稻品种PI对受体稗草根干重的抑制能力明显提高，在处理后的5 、10和15 d，其对稗草地下部干重的抑制率分别增加了5.64%、3.89%和12.13%，增加幅度比非化感水稻品种Le显著.生理生化分析结果表明，与正常营养条件相比，用低磷营养下生长的化感水稻PI的根系分泌物处理稗草5、10和15 d，受体稗草叶片中POD活性的促进率分别提高了20.19%、15.47%和6.68%，吲哚乙酸氧化酶活性的促进率分别提高了18.08%、17.71%和12.50%，硝酸还原酶活性的抑制率分别增加了13.89%、18.60%和2.10%. 在低磷营养胁迫下，化感水稻通过抑制受体植物的硝酸还原酶活性，影响其对氮营养的吸收，同时显著提高了吲哚乙酸氧化酶活性，减缓了受体稗草的生长速度，提高了其抑草作用潜力.

Allelopathic potential and physiological mechanism of Oryza sativa L. under phosphorus deficiency stress

In this paper, allelopathic rice PI312777 (PI) and non-allelopahtic rice Lemont (Le) were grown in the nutrient solution with two levels of phosphorus (P) supply, and their allelopathic effects on Echinochloa crus-galli L. were studied. The results showed that under phosphorous deficiency stress, the inhibitory effect of PI on E. crus-galli root growth had an obvious increase. After growing in the nutrient solution with low P supply (0.5 mg x L(-1)) for 5, 10 and 15 days, the inhibitory rate of PI on E. crus-galli root dry matter increased by 5.64%, 3.89% and 12.13%, respectively, while that of Le did not show the same trend, compared with normal P supply. With low P supply for 5, 10 and 15 days, PI allelopathic effect on the leaf POD activity of E. crus-galli increased by 20.19%, 15.47% and 6.68%, IAAoase activity increased by 18.08%, 17.71% and 12.50%, while NR activity increased by 13.89%, 18.60% and 2.10%, respectively, suggesting that under P deficiency, PI enhanced its allelopathic potential through two pathways, i.e., to increase the weed POD and IAAoase activities to slow down its growth rate, and to decrease the weed NR activity to affect its N uptake.