油菜素内酯对干旱胁迫下山杏光合作用的影响

摘要

In order to examine the effect of brassinolide(BR) on the photosynthesis of Prunus armeniaca L.var. ansu under drought stress, the diurnal changes of photosynthesis and chlorophyll contents of P. armeniaca seedlings were measured and analyzed by using potted-seedlings to control soil water and dipping roots and spraying leaves of seedlings with 0.2 mg· L-4 BR. The results showed that BR had no effect on diurnal change trend of photosynthetic parameters of Pn, Tr,Gs and Ci of the seedlings under both light and severe drought. Under light drought conditions, the opening of leaf stomata increased by the treatment of 0.2 mg · L-1 BR at noon and in the afternoon. At the same time the photosynthetic activities of leaf cells were enhanced and the photosynthesis of the seedlings was improved. Under severe drought conditions,the opening of leaf stomata increased by the treatment of 0.2 mg · L-1 BR in the afternoon. But the photosynthetic activity of leaf cells was no affected and it was limited for improvement of photosynthesis. Because of the opening of leaf stomata, the transpiration of the seedlings was intensified and this resuited in a large loss of water. There was no significant effect on chlorophyll contents under both light and severe drought conditions.%采用盆栽试验,在控水条件下用蘸根和叶面喷施0.2 mg·L-1油菜素内酯(BR)的处理方法,对黄土丘陵区主要造林树种山杏苗的光合日变化及叶绿素含量进行了测定和分析.结果表明:无论是轻度还是重度干旱下,BR处理苗与对照苗的Pn、Tr、GST Ci等光合参数日变化趋势基本一致.但在轻度干旱下0.2 mg·L-1的BR处理在午间及午后增加了山杏苗叶片的气孔开张,增强了叶肉细胞的光合活性,从而促进了山杏苗的光合作用;在重度干旱下,0.2 mg·L-1的BR处理在午后增加叶片气孔开张,对叶肉细胞的光合活性影响不显著,对山杏苗光合作用的促进有限.由于气孔的开张使山杏苗蒸腾加剧,导致大量水分散失.BR处理对处于轻度和重度干旱下山杏苗的叶绿素含量均没有显著的影响.