地膜覆盖穴播小麦光合和干物质积累特点分析

地膜覆盖穴播小麦在拔节期、孕穗期和灌浆期的日平均光合速率分别比对照高23．3％、33.1％和12．7%。在拔节期光合速率日变化为单峰型，而在孕穗期和灌浆期则为双峰型。净同化率比对照高0．38g/（m2·d）和0.23g/（m2·d）。地膜覆盖穴播小麦具有叶面积大．光合“午睡”现象轻和干物质积累多的特点。光合速率高低与气孔阻力有关。覆膜小麦表现为气孔阻力低于对照，这有利于植株叶片气体交换和光合能力的提高，其主要原因是全生育期覆膜小麦的土壤水分供应状况好于露地。

Analysis on characters of photosynthesis and dry matter accumulation of hill sowing spring wheat under plastic mulching

The mean diurnal rates of photosynthesis (RP)of hill sowing spring wheat under plastic sheet mulching were 1.11×103 mg CO2·m-2·h-1, 1.37 × 103 mg CO2·m-2·h-1 and 1. 16 ×103 mg CO2·m-2·h-1 at the shooting, ear bearing and fill stage separately, that were 23.3 %, 33.1 %and 12.7 % increases as compared with the outdoor wheat (CK). The diurnal RP variation of wheat under film covering displayed a single peak curve at the shooting stage but double ones atear bearing and fill period. The highest and average net assimilation rates (NAR) were 13.01 g·m-2d-1 and 8.24 g·m-1·d-' that were over 0-38 and 0.23 g.m-'d-1 than the control. The hill sowing wheat under plastic covering had bigger leave area, more chlorophyll content as well as fasterspeed of dry matter accumulation. RP was correlated with stomata resistance and transpiration rate. Wheat under plastic covering displayed lower stomata resistance that was beneficial to airexchanging of leaves and improving photosynthetic intensity.The important reason for that was the water regime in plant 0f wheat plastic covering was better than the control.