Liu Zhao-wei, Zhang Pan, Wang Rui, Kuai Jie, Li Lei, Wang You-hua, Zhou Zhi-guo
Ying Yong Sheng Tai Xue Bao. 2014 Dec;25(12):3533-9.
To investigate the dynamic changes and response mechanisms of gas exchange parameters and fluorescence indices of the subtending leaf to cotton boll under soil progressive drought stress, pot experiments of the hybrid cotton No. 3 were conducted with soil relative water content (SRWC) (75 +/- 5)% as control group, SRWC (60 +/- 5)% and SRWC (45 +/- 5)% as experimental groups dealt with progressive drought for 50 days. Results showed that, the net photosynthetic rate (Pn), stomatal conductance (g(s)) and leaf intercellular CO2 concentration (Ci) decreased while Ls increased under SRWC (60 +/- 5)% for 0-21 days. Furthermore, there was no significant change in chlorophyll fluorescence indices. This indicated that stomatal limitation was the main reason for the reduction of photosynthesis of cotton. In addition, when drought for 21-49 days under SRWC (60 +/- 5)%, Pn kept decreasing, while Ci began to increase and Ls began to decrease. Potential photochemical efficiency (Fv/Fm), quantum yield of photo system II (phi(PSI)) and photochemical quenching coefficient (q(P)) reduced significantly, but non-photochemical quenching coefficient (NPQ) first rose then decreased. Thus, nonstomatal limitation was the main reason why the photosynthesis of cotton reduced. Photosynthetic organization and photosynthetic enzyme system were destroyed, boll setting intensity reduced and the number of boll and yield reduced significantly. Drought for 0-14 days under SRWC (45 +/- 5)% treatment led to sharp decrease in Pn, g(s) and Ci, whereas Ls obviously increased. There was no significant change in Fv/Fm, phi(PSII), q(P), indicating stomatal limitation was the main reason why the photosynthesis of cotton reduced. Pn decreased slowly, while Ci began to rise and Ls began to decline under SRWC (45 +/- 5)% treatment for 14-49 days. Fv/Fm, phi(PSII), q(P) decreased while NPQ rose first then declined, which indicated that nonstomatal limitation worked to reduce the cotton photosynthetic performance. The boll setting intensity reduced significantly and the number of boll and yield declined. The critical stress time of cotton growth in current study was 21 and 14 days respectively under SRWC (60 +/- 5)% and SRWC (45 +/- 5)% treatments during the flowering and boll-forming stage.
为探究土壤渐进干旱胁迫下棉花棉铃着生叶气体交换参数和荧光指标的动态变化及响应机制，以土壤相对含水量（SRWC）（75±5）%为对照组，SRWC（60±5）%和SRWC（45±5）%为实验组，对杂交棉3号进行盆栽试验，使其进行50天的渐进干旱处理。结果表明，在SRWC（60±5）%处理0 - 21天期间，净光合速率（Pn）、气孔导度（g(s)）和叶片胞间CO₂浓度（Ci）下降，而气孔限制值（Ls）升高。此外，叶绿素荧光指标无显著变化。这表明气孔限制是棉花光合作用降低的主要原因。另外，在SRWC（60±5）%处理下干旱21 - 49天，Pn持续下降，而Ci开始升高，Ls开始下降。潜在光化学效率（Fv/Fm）、光系统II量子产量（phi(PSI)）和光化学猝灭系数（q(P)）显著降低，但非光化学猝灭系数（NPQ）先升高后下降。因此，非气孔限制是棉花光合作用降低的主要原因。光合机构和光合酶系统遭到破坏，结铃强度降低，棉铃数和产量显著减少。在SRWC（45±5）%处理下干旱0 - 14天导致Pn、g(s)和Ci急剧下降，而Ls明显升高。Fv/Fm、phi(PSII)、q(P)无显著变化，表明气孔限制是棉花光合作用降低的主要原因。在SRWC（45±5）%处理14 - 49天期间，Pn缓慢下降，而Ci开始上升，Ls开始下降。Fv/Fm、phi(PSII)、q(P)下降，而NPQ先升高后下降，这表明非气孔限制作用导致棉花光合性能降低。结铃强度显著降低，棉铃数和产量下降。本研究中棉花生长在开花结铃期，SRWC（60±5）%和SRWC（45±5）%处理下棉花生长的临界胁迫时间分别为21天和14天。
