不同供氮水平及水分调控条件下水稻光合作用光响应特征

为了揭示不同水氮调控对水稻功能叶片光合作用光响应特征的影响,在2种供氮水平下,针对分蘖末期和拔节孕穗期开展了不同土壤水分状况下水稻功能叶片光合速率的光响应特征研究。实测结果表明,随土壤水分的降低,水稻功能叶片的光响应曲线下降,且在光强高于400μmol/(m2.s)时,不同土壤水分状况的光响应曲线差距变大,低氮处理光响应曲线受水分亏缺的影响较大。基于实测结果,建立水稻叶片光合速率光响应曲线的数学模拟,得到不同水氮处理水稻功能叶片光响应的特征参数,结果显示最大净光合速率、光饱和点随着土壤水分的降低而下降、其中低氮处理下降幅度较大,在复水后均出现反弹。因此,水分胁迫会降低水稻叶片对强光的适应能力,但此能力在复水后可恢复,在200～300kg/hm2施氮量范围内,增加施氮量可以有效改善叶片光响应特征、并有效促进复水之后反弹补偿的产生,在制定水稻节水灌溉的土壤水分调控指标时,要考虑不同的施氮水平的影响。

Characteristics of rice leaf photosynthetic light response curve with different water and nitrogen regulation

In order to reveal the influence of soil moisture and nitrogen regulation on characteristics of rice leaf photosynthetic light response pots experiments were carried out.Leaf photosynthetic light response curves were measured in later tillering stage and booting-jointing stages,under different soil moisture conditions with two nitrogen levels.With soil moisture depletion,photosynthetic light response curves reduced,especially when the photosynthetic photon flux density was higher than 400 μmol/(m2?s).Parameters derived from photosynthetic light response model indicated maximum photosynthesis rate Pnmax and light saturation points LSP reduced with decrease in soil moisture,and recovered after rewetting.Reduced nitrogen inputs were likely aggravating the reduction in photosynthetic light response curves,Pnmax and LSP.It can be concluded that water stress leads to inhibition on adaptive capacity of rice leaf photosynthesis to strong light,which would be recovered after rewetting.High nitrogen inputs,within the range of 200-300 kg/hm2,can be helpful to improve leaf photosynthetic light response characteristics,and enhance the recovery and compensation effects.Criteria of soil moisture regulation for rice water saving irrigation should be determined according to different nitrogen levels in rice paddy.