水分胁迫下氮、钾对不同基因型夏玉米氮代谢的影响

Effects of application of N and K fertilizers on nitrogen metabolism of two genetype varieties of maize under water-stressed condition

采用盆栽试验研究了水分胁迫和适量供水条件下,氮、钾对2种基因型夏玉米陕单9号(抗旱品种)和陕单911(不抗旱品种)各生育期体内硝酸还原酶活性、脯氨酸、甜菜碱和可溶性蛋白质积累的影响,旨在从氮代谢方面揭示这些因子的抗旱机理。试验结果表明,水分胁迫下,硝酸还原酶活性显著降低,不抗旱品种降低更甚;脯氨酸、甜菜碱和可溶性蛋白质有不同程度累积,抗旱品种含量和变幅大于不抗旱品种。2品种苗期对水分胁迫响应较弱,脯氨酸、甜菜碱和可溶性蛋白质含量低;拔节和抽雄期响应强烈,这些化合物含量增高,其中甜菜碱含量达到高峰时间比脯氨酸晚。水分胁迫下,施用氮肥能显著提高硝酸还原酶活性及脯氨酸、甜菜碱和可溶性蛋白质含量,改善氮代谢。不抗旱品种2种氮肥用量的效果有显著差异;抗旱品种在低氮用量时效果显著,低、高氮肥用量间无显著区别。适量供水下,氮肥作用明显下降,表明氮肥不仅在于供应养分,而且还能通过改善氮代谢而增强作物的抗旱性能。钾肥对受水分胁迫的夏玉米表现出比氮肥更突出的效果,而在适量供水时效果消失,表明在作物受旱条件下,显著改善作物氮代谢是钾增强作物抗旱性的主要机理之一。

A pot experiment was conducted under water stress and adequate water applying conditions with two genotype varieties of maize （Shaandan 9, a drought-resistant variety and Shaandan 911, a non-drought-resistant variety） to study the effects of nitrogen, potassium on NR （nitrate reductase） activity, accumulations of proline, glycine betaine and soluble protein in maize leaves at different growing stages for revealing their biological function in increase of plant resistance to drought through nitrogen metabolism. Results showed that under a water stress condition, NR activity was significantly reduced while concentrations of proline, glycine betain and soluble protein were increased. The drought resistant variety was higher in values and variation of FIR activity, cncentration of soluble proline, glycinebetain and soluble protein than non-drought resistant variety. The response of the two varieties to water stress was weaker at seeding stage as shown in their lower concentrations of proline, glycine betaine and soluble protein while stronger at elongation and heading stages as shown in higher concentrations of these compounds. Of those compounds, the peak value of glycine betaine appeared later compared with proline. betaine and soluble protein, Application of nitrogen significantly raised NR activity and concentrations of proline, glycine and hence alleviated the water stress through improvement of nitrate metabolism. The effects of N application for non-drought resistant varieties were significantly different. The response of the drought-resistant variety to N addition was merely found at low rate, but there was no significant different between high and low N rates. With adequate water supply, effects of N fertilization were significantly decreased, showing that in addition to function as a nutrient, N fertilizer played a biological role in increasing drought-resistance of the crop through improving nitrogen metabolism. Potassium had stronger influence on NR activity and under the water stress condition comparing with N while the effect contents of proline, glycine betaine and soluble protein of K fertilization on metabolism was even vanished under adequate water supply condition, indicating that to markedly improve nitrogen metabolism is one of the key mechanisms of potassium to enhance drought resistance of crops.