减量施氮对苦荞产量形成及氮代谢酶活性的影响

为明确减量施氮对苦荞强弱势粒及产量形成的影响,以苦荞品种晋荞2号为试验材料,研究在225 kg/hm²(N1)、135 kg/hm²(N2)、45 kg/hm²(N3)、0 kg/hm²(N4,对照)4个氮肥处理下苦荞强弱势粒的灌浆动态、根系形态生理、叶片中叶绿素含量及氮代谢相关酶活性、农艺性状和产量的差异.结果显示:减氮处理下,N2处理时晋荞2号籽粒的灌浆起始势(R0)、最大灌浆速率(Gmax)和平均灌浆速率(Gmean)最大,达最大灌浆速率的时间(Tmax.G)最小;强弱势粒间以强势粒的A值(生长终值量)、R0、Gmax和Gmean大于弱势粒,而N值(形状参数)和Tmax.G则低于弱势粒. 4个氮肥处理和强弱势粒均以灌浆中期对粒重的贡献率最大,灌浆后期次之,灌浆前期最小.随着施氮量的减少,晋荞2号的根系长度等形态指标及根系活力呈先增加后降低的趋势,以N2处理最大;随着施氮量的减少,晋荞2号叶片中的叶绿素含量及谷氨酰胺合成酶(GS)、谷氨酸脱氢酶(GDH)、谷氨酰胺合酶(GOGAT)、硝酸还原酶(NR)活性呈先增加后降低的趋势,N2处理最大,强弱势粒间以强势粒的叶绿素含量较高、氮代谢酶活性较大. N2处理时的株高等农艺性状及产量形成指标均大于其余3个氮肥处理.本研究表明适当减量施氮可延缓苦荞衰老、促进苦荞强弱势粒的灌浆和氮代谢酶活性的增加,提高粒重和最终产量,进而实现节肥和高产.(表7参31)

Effect of reduced nitrogen application on yield formation and nitrogen metabolism enzyme activity of tartary buckwheat

The objective of this study was to clarify the effect of reducing nitrogen application on the formation of an inferior spikelet and the yield formation of tartary buckwheat. Four nitrogen treatments, 225 kg/hm²(N1), 135 kg/hm²(N2), 45 kg/hm²(N3), and 0 kg/hm²(N4, CK) were established with Jinqiao2(JQ2), a tartary buckwheat variety, as the experimental organism. The effects on grain filling dynamics of superior and inferior spikelets, root morphology and physiology, chlorophyll content and nitrogen metabolism-related enzyme activity in leaves, agronomic characteristics, and yield of tartary buckwheat were studied. The time to reach the maximum grain filling rate(Tmax.G) was the shortest for the N2 treatment, while the initial growth power(R0), maximum grain filling rate(Gmax), and average grain filling rate(Gmean) were the highest. The A value(final growth value), R0, Gmax, and Gmean of the superior spikelet were higher than those of the inferior spikelet, whereas its N values(shape parameter) and Tmax.G were lower. The middle filling stage made the largest contribution to grain weight, followed by the later filling stage, and the smallest contribution was in the early filling stage. With decreased nitrogen application, the total root length, root surface area, root volume, root average diameter, and root activity of JQ2 showed a tendency to first increase and then decrease;in addition, the chlorophyll content, and the activity of glutamine synthase(GS), glutamate dehydrogenase(GDH), glutamic acid synthetase(GOGAT), and nitrate reductase(NR) in leaves first increased and then decreased. The chlorophyll content and activity of nitrogen metabolism enzyme activity of the superior spikelet were higher than those of the inferior spikelet. The agronomic traits and yield from N2 treatment were higher than those from the other three treatments. Appropriate reduction of nitrogen application can delay the senescence of tartary buckwheat, promote the filling of superior and inferior spikelets, increase nitrogen metabolic enzyme activity and increase grain weight and final yield, thus achieving the goal of combining fertilizer and high yield.