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以盆栽2年生的金矮生为试材研究了短期土壤干旱对苹果叶片光合速率日变化的影响以及光合速率日变化与叶片水势日变化的关系.短期土壤干旱明显改变了苹果叶片光合速率的日变化进程.夏、秋季节短期中度土壤干旱导致叶片产生“午休”现象.“午休”发生时先表现为气孔限制,后为非气孔限制.叶片水势与光合速率、气孔导度呈阈值关系,阈值水势为-2.15MPa,叶片水势降至阈值之下,光合速率,气孔导度迅速降低,但叶片水势的日变化与光合速率的日变化没有明显的关系.
The effects of short-term soil drought on the diurnal changes of photosynthetic rate of apple leaves and the relationship between diurnal changes of photosynthetic rate and diurnal changes of leaf water potential were studied using potted two-year-old golden dwarfs.The short-term soil drought obviously changed the photosynthetic rate of apple leaves The mid-summer and autumn seasonal short-term soil drought led to the phenomenon of “midday break” in the leaves.The “midday depression” first showed stomatal limitation and non-stomatal limitation later.The leaf water potential showed a threshold relationship with photosynthesis rate and stomatal conductance, The threshold water potential was -2.15MPa, and the leaf water potential dropped below the threshold, and the photosynthetic rate and stomatal conductance decreased rapidly. However, the leaf water potential had no obvious relationship with the diurnal variation of photosynthetic rate.