Liu Rui-Xian, Guo Wen-Qi, Chen Bing-Lin, Zhou Zhi-Guo
Ministry of Agriculture Key Laboratory of Crop Growth Regulation, Nanjing Agricultural University, Nanjing 210095, China.
Ying Yong Sheng Tai Xue Bao. 2008 Jul;19(7):1475-82.
With pot culture, the physiological responses of cotton plant to fertilizer nitrogen at flowering and boll-forming stages were studied under soil drought and after re-watering. The results showed that under soil drought, the net photosynthetic rate (Pn) and transpiration rate (Tr) declined rapidly with decreasing soil relative water content (SRWC). At the early stage of soil drought, owing to the declining degree of Tr was greater than that of Pn, the WUE had an increasing trend; but after then, the WUE decreased with declining SRWC and Pn. Soil drought altered the diurnal patters of Pn and Tr, i.e., decreased continuously from 8:00 to 16:00, while in CK, their peak values appeared at 10:00-11:00 and 12:00, respectively. The diurnal patterns of WUE in drought treatment and CK were the same, i.e., decreased first and increased then, with the bottom appeared at 12:00. Under soil drought, the Pn and Tr decreased with increasing fertilizer nitrogen level, while WUE was in adverse. After re-watering, the diurnal patterns of Pn, Tr and WUE were similar to CK, but their values were smaller than CK, especially under nitrogen application. It was suggested that under soil drought, nitrogen fertilization could be helpful to the increase of water use efficiency, but decreased the photosynthesis of cotton plant at its flowering and boll-forming stages.
通过盆栽试验，研究了土壤干旱及复水条件下棉花植株在开花结铃期对肥料氮的生理响应。结果表明，在土壤干旱条件下，随着土壤相对含水量（SRWC）的降低，净光合速率（Pn）和蒸腾速率（Tr）迅速下降。在土壤干旱初期，由于Tr的下降幅度大于Pn，水分利用效率（WUE）呈上升趋势；但此后，随着SRWC和Pn的下降，WUE降低。土壤干旱改变了Pn和Tr的日变化模式，即从8:00至16:00持续下降，而在对照（CK）中，它们的峰值分别出现在10:00 - 11:00和12:00。干旱处理和CK中WUE的日变化模式相同，即先下降后上升，谷底出现在12:00。在土壤干旱条件下，Pn和Tr随肥料氮水平的增加而降低，而WUE则相反。复水后，Pn、Tr和WUE的日变化模式与CK相似，但它们的值小于CK，尤其是在施氮条件下。结果表明，在土壤干旱条件下，施氮有助于提高水分利用效率，但降低了棉花植株开花结铃期的光合作用。
