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在农业生产体系中,作物与大气间的氨气交换对于估算氮素需求具有重要意义。然而,作物氨气动态的生理基础仍不清楚。本研究旨在描述生长箱内,良好供肥的小麦植株从早期营养生长到成熟的氨气流动过程;在静态全株气体交换袋内调查了生育期及光呼吸对植株NH_3及CO_2交换的影响,并确定了籽粒灌浆期的NH_3补偿点。试验自始至终观察了在周围充满NH_3气体条件下,小麦植株的NH_3释放(损失)状况。尽管以叶面积为基础来表述,NH_3与CO_2两种气体的变化趋势有别,但是叶面积对这两种气体交换速率影响很大。光呼吸只与NH_3释放的水平有适度关系。NH_3释放最高速率出现在籽粒灌浆期,在开花后和成熟前分别表现出两次爆发性的高度活动。随着植株成熟,NH_3补偿点升高。生育晚期NH_3释放的潜势增强与个体发育的氮代谢变化有关,后期氮代谢使植株组织中的(NH_4~+]浓度比幼龄营养组织中的要有所升高。
In agricultural systems, the exchange of ammonia between crops and the atmosphere is of great importance for estimating nitrogen demand. However, the physiological basis of crop ammonia dynamics remains unclear. The aim of this study was to describe the flow of ammonia from early vegetative to mature wheat plants in a growth chamber and to examine the effects of growth and photorespiration on the exchange of NH_3 and CO_2 in a static whole-plant gas exchange bag , And determined the grain filling stage of NH_3 compensation point. From the beginning to the end of the experiment, the NH3 release (loss) status of wheat plants was observed under the condition of being surrounded by NH3 gas. Although the changes of NH 3 and CO 2 gases are different based on the leaf area, the leaf area has a great influence on the exchange rates of these two gases. Photo respiration is only moderately related to the level of NH_3 release. The highest rate of NH_3 release occurred during the grain filling stage and showed two highly explosive activities after flowering and before maturity. As plants matured, the NH 3 compensation point increased. The enhanced release of NH_3 in late stage of fertility was related to the change of nitrogen metabolism in individual development. The late stage of nitrogen metabolism increased the concentration of (NH_4 ~ +) in plant tissues than that in young vegetative tissues.