施氮对不同抗旱性冬小麦叶片光合与呼吸的调控

在大田条件下对两个不同抗旱特性的冬小麦品种全生育期叶片光合气体交换参数、光合色素含量和呼吸值及其对氮素水平的响应进行了研究.结果表明，施氮180 kg·hm^-2处理旱地品种叶片气孔导度、总光合色素含量、光合速率较不施氮处理在全生育期分别提高了43.75%、18.54%和49.66%，水地品种分别提高了12.12%、20.88%和29.25%；而旱地品种总呼吸速率降低了4.8%，水地品种降低了4.5%.适量施氮，增强了小麦叶片的气体交换能力，提高了光合色素含量，并降低了呼吸速率，从而提高了小麦叶片光合碳同化能力.小麦品种间光合的差异主要由非气孔因素引起.旱地品种呼吸速率较低，吸收的光能较多地用于光合碳同化作用.不施氮处理叶片光合速率较高的生育时期其呼吸速率也高，而施氮处理叶片光合速率高的生育时期呼吸值较低.施氮增加了光能向光合碳同化方向的分配.施氮对提高冬小麦抗旱能力有积极作用，其机理在于氮素改善了叶片气体交换状况，提高了光合色素含量，并优化了叶片对光能吸收的分配.

Effects of nitrogen fertilization on leaf photosynthesis and respiration of different drought-resistance winter wheat varieties

.Under field condition, this paper measured the leaf gas exchange parameters and photosynthetic pigments content of different drought-resistance wheat varieties at all growth stages, with their responses to different nitrogen fertilization levels studied. The results showed that in treatment N_ 180 , the leaf G_s, P_n, and total photosynthetic pigments content of dry land varieties increased by 43.75%, 18.54% and 49.66%, while those of watered land varieties increased by 12.12%, 20.88% and 29.25%, respectively, compared with control. On the contrary, the respiration rate of dry land and watered land varieties decreased by 4.8% and 4.5%, respectively. Nitrogen supply accelerated the photosynthetic carbon assimilation, because the gas exchange capacity and photosynthetic pigments content increased while the respiration rate decreased with increasing nitrogen supply. The difference in photosynthetic capacity between different winter varieties was mainly dependent on non-stomatal factors. The dry land varieties had higher capacities of light energy absorption and photosynthetic carbon assimilation, because they had higher leaf photosynthetic pigments content but lower respiration rate. Compared with watered land varieties, dry land varieties had an 8.9% decrease of respiration rate and a 14.12% increase of P_n. At the same growth stage, the photosynthetic and respiration rates in the control varied consistently, while in treatments N_ 180 and N_ 360 , the photosynthetic rate increased but the respiration rate decreased. Nitrogen fertilization promoted the absorbed light energy allocating to the process of photosynthetic carbon assimilation. It could be concluded that nitrogen supply was favorable to the improvement of winter wheat drought-resistance, because it could improve leaf gas exchange capacity, increase leaf photosynthetic pigments content, and optimize the allocation of absorbed light energy.