调亏灌溉下番茄叶片气体交换日变化和光响应特性

以原料番茄“里格尔87-5”为试验材料,设置正常灌水、轻度亏水和中度亏水3个水平,对水分亏缺条件下番茄果实膨大期光合作用日变化及光合速率对光强度的响应进行研究,以对原料番茄光合能力进行探讨并模拟适合亏水条件下光响应过程。结果表明:(1)轻度亏水条件下,番茄叶片气体交换特性与对照无显著差异,但中度亏水条件下净光合速率、气孔导度、蒸腾速率显著降低。(2)利用直角双曲线模型、非直角双曲线模型、指数函数模型和直角双曲线修正模型,对表观量子效率、最大净光合速率、暗呼吸速率、光饱和点、光补偿点进行模拟,4个模型对光响应曲线的拟合程度较高,但直角双曲线修正模型拟合结果与实测值最符合。(3)不同水分条件下的表观量子效率、最大净光合速率与光合速率日均值显著相关,而光合速率日均值与产量显著正相关;中度亏水造成光合速率日均值显著降低,最终影响了产量;轻度亏水下番茄能够维持正常光合作用,在不显著降低产量的同时实现节水目标。

Gas Exchange and Photosynthetic Response to Light in Tomato Leaf under Regulated Deficit Irrigation

The responses of photosynthetic diurnal variation and net photosynthetic rates of tomato (processing type, cv. Riegel 87-5) during fruit enlarging stage to light density under three irrigation levels were studied to evaluate tomato photosynthetic capability and models suitable for tomato photosynthesis simulation in water deficit condition. The results showed that: (1) the gas exchange characters of tomato leaves under slightly water stressed had no significant difference with the control, but the net photosynthetic rate, stomatal conduction and evaporation rate decreased significantly under middle level water stress. (2) Four models of rectangular hyperbolic model, non-rectangular hyperbolic model, exponential model and modified rectangular hyperbolic model can all be used to simulate the apparent quantum yield, maximum net photosynthetic rate, dark respiration rate, light saturation and compensation points of tomato, but the modified rectangular hyperbolic model gave the best math fitting results compared with the measured values. (3) Under different water conditions, the apparent quantum yield (α), maximum net photosynthetic rate (P_nmax) were significantly positively related to the mean photosynthetic rate, and the mean photosynthetic rate was significantly and positively associated with fruit yield. The mean photosynthetic rate, and ultimately the fruit yield decreased under moderate water stress. While slightly deficit irrigation did not decrease fruit yield of processing tomato significantly and resulted in higher water use efficiency.