氮素形态配比对菜用大豆籽粒膨大过程中氮碳同化的影响

以菜用大豆品种‘理想95-1'为试材,通过蛭石盆栽试验研究了氮素不同形态配比对菜用大豆籽粒膨大过程中碳氮代谢的影响.结果表明:营养液中增加适当的铵态氮比例(25%～50%)有利于菜用大豆的生长发育,菜用大豆植株和荚果干鲜重、干物率显著增加,尤以硝铵比为75∶25最为显著.在高比例的硝态氮(100%)或铵态氮(75%)处理下,菜用大豆籽粒的硝酸还原酶(NR)和谷氨酰胺合成酶(GS)活性分别显著升高,氮代谢显著增强,可溶性蛋白含量迅速增加,但同期的籽粒淀粉酶活性较低,可溶性糖和淀粉含量显著下降,碳代谢受到显著抑制.在硝铵比为75∶25时,菜用大豆籽粒氮代谢强度适中,同期碳代谢显著增强,籽粒可溶性糖和淀粉含量显著升高,能维持籽粒正常的生理代谢,有利于菜用大豆籽粒发育过程中营养物质的积累.可见,硝态氮和铵态氮配比能显著影响菜用大豆籽粒发育过程中的碳氮代谢,籽粒碳氮代谢与其产量密切相关,可通过调节硝铵比来获得理想菜用大豆产量.

Effects of Nitrogen Forms and Ratios on Carbon-nitrogen Assimilation in Developing Seeds of Vegetable Soybean

Using vermiculite culture,we studied the effects of NO_3~--N∶NH_4~+-N ratios on carbon-nitrogen assimilation in developing seeds of vegetable soybean Glycine max (L.) Merr.cv.Li-xiang 95-1].The results showed that the appropriate NH_4~+-N ratio between 25% and 50% in nutrient solutions was beneficial to the growth and development of vegetable soybean,and the fresh weight,dry weight (DW) and DW percentage increased significantly,especially in NH_4~+-N (25%).Under the treatment of excessive nitrate (100%) or ammonium (75%),the activities of nitrate reductase (NR) and glutamine synthetase (GS) in vegetable soybean seeds increased significantly,respectively,and the increasing nitrogen metabolism led to that soluble protein content increased significantly,but the amylase activity,soluble sugar and starch contents decreased significantly and the seeds was moderate and also the carbon metabolism increased obviously and the soluble sugar and starch contents increased significantly at the same time,so the normal physiological metabolism in seeds was maintained and resulted in the accumulation of nutrients in developing seeds of vegetable carbon-nitrogen assimilation in developing seeds of vegetable soybean,and the carbon-nitrogen metabolism in seeds is closely related to the yield,so enhance the yield of vegetable soybean.