调亏灌溉和施氮对玉米叶片保护系统的影响

通过盆栽试验,研究了不同生育期亏水和氮肥处理对春玉米叶片丙二醛(MDA)含量、可溶性糖(SS)含量、过氧化物酶(POD)和超氧化物歧化酶(SOD)活性的影响.结果表明,调亏灌溉可使玉米叶片MDA和SS含量明显升高,而使POD和SOD活性有所降低.施氮处理能保证叶片在抽雄期前SS含量、SOD和POD活性处于较高水平.MDA含量与灌水和施氮水平呈负相关,拔节后期达最大值,之后减小.从苗期到拔节后期,调亏灌溉施氮处理的可溶性糖含量较高,而高氮持续亏水处理可导致可溶性糖含量降低.POD活性到拔节后期达到最大,抽雄期有所降低.亏水处理明显降低了叶片POD活性,复水后补偿效应明显.施氮可适当提高POD活性,但抽穗亏水和全生育期亏水高氮处理在抽雄期的酶活性降低.SOD活性的变化趋势和POD相似.苗期亏水处理在复水后各生理生化指标补偿效果较好,拔节期亏水处理次之.高氮处理不宜在抽雄期调亏灌溉.调亏灌溉和施氮的最佳处理组合为苗期调亏低氮处理.

Effect of regulated deficit irrigation and nitrogen fertilization on maize leaf protective system

A pot experiment was conducted on spring maize to determine the effect of the water deficit period and nitrogen application rate on leaf protective system of malondialdehyde (MDA), soluble sugar (SS) contents as well as peroxidase (POD) and superoxide dismutase (SOD) activity. The study shows that while regulated deficit irrigation increases MDA and SS contents, it at the same time decreases POD and SOD activity. Nitrogen application ensures high levels of SS, SOD and POD before heading. MDA content is negatively correlated with nitrogen rate and irrigation level, reaching its peak in the late stage of jointing, and then decreasing. Nitrogen application in regulated deficit irrigation leads to a relatively high SS content from seedling to terminal jointing stage, whereas high nitrogen application rates in continuous water deficit decreases SS content. POD activity is maximum at terminal jointing stage, decreasing during heading stage. Water deficit significantly decreases POD activity, with a significant compensation effect after re-flood irrigation. Although nitrogen application enhances POD activity, but high nitrogen dose with water deficit in heading or during whole growing stage decreases POD activity at heading stage. SOD activity trend is consistent with that of POD. Compensation effect of re-flood irrigation is better for physiology and biochemistry under water deficit at seedling stage, and it takes the second place under water deficit at jointing stage. High nitrogen treatment is not suitable for water deficit irrigation at heading stage. The best treatment combination is water deficit at seedling stage with low nitrogen dose.