水分胁迫对成年荔枝不同季节光合速率日变化的影响

Effects of Water Stress on Diurnal Changes in the Net Photosynthetic Rate of Adult Litchi in Different Seasons

摘要:

以16 a生‘糯米糍’ 荔枝( Litchi chinensis Sonn. cv. Nuomizi)为试材，研究了其在水分胁迫下不同季节的光合速率日变化。结果表明，保湿处理的净光合速率(Pn)日变化在秋、夏季呈单峰曲线，冬、春季为双峰曲线；干旱处理除在冬季出现双峰曲线外，其他季节均呈单峰曲线。两个处理的Pn日变化最大值或第1个峰值出现时间基本一致，冬季为9 :00、春季和夏季为10 :00、秋季为12 :00。保湿处理的日最高Pn变化范围为6.25-8.14 μmol m-2s-1, 干旱处理的在4.35-6.56 μmol m-2s-1；中度水分胁迫对田间成年荔枝树的光合速率具有较大的抑制作用, 干旱对日净光合总量的抑制比例分别为：冬季18.6%，夏季21.3%，春季34.1%，秋季34.7%。在光合作用旺盛时段(8:00-16:00)中度水分胁迫导致叶片Pn的降低主要是由气孔因素所致。

Abstract:

Effects of water stress on the diurnal changes of the net photosynthetic rate (Pn) in different seasons were investigated in 16-year-old trees of Litchi chinensis Sonn. cv. Nuomizi. In wet treatment the diurnal curves of Pn exhibited double peaks in autumn and summer, and a single peak in winter and spring, whereas in drought treatment they exhibited two peaks in winter and single peak in the other seasons. The maximum Pn or the first peak during daytime was generally the same in both treatments, which occurred at 9:00 in winter, 10:00 in spring and summer, 12:00 in autumn. The maximum Pn in wet- and drought-treated trees ranged from 6.25 μmol m-2s-1 to 8.14 μmol m-2s-1 and from 4.35 μmol m-2s-1 to 6.56 μmol m-2s-1, respectively. Moderate water stress could largely inhibit the photosynthesis of litchi tree, and the amount of daily Pn was decreased by 18.6%, 21.3%, 34.1% and 34.7% in winter, summer, spring and autumn, respectively. It was suggested that moderate water stress leads to Pn decrease by affecting stomatal conductance (Gs).