Chin J Plan Ecolo ›› 2014, Vol. 38 ›› Issue (10): 1124-1134.DOI: 10.3724/SP.J.1258.2014.00107

• Research Articles • Previous Articles     Next Articles

Responses of photosynthetic characteristics to low temperature stress and recovery treatment in cotton seedling leaves

WU Hui, DAI Hai-Fang, ZHANG Ju-Song*, JIAO Xiao-Ling, LIU Cui, SHI Jun-Yi, FAN Zhi-Chao, and ALIYAN·Rouzi   

  1. College of Agronomy, Xinjiang Agricultural University; Research Center of Cotton Engineering, Ministry of Education, Ürümqi 830052, China
  • Received:2014-05-19 Revised:2014-07-15 Online:2014-10-01 Published:2014-10-22
  • Contact: ZHANG Ju-Song

Abstract:

Aims The objective of this study was to investigate the responses of photosynthetic traits to varying degrees of low temperature stress and recovery treatment, in order to provide a theoretical basis for enhancing the cold tolerance of cotton seedlings and avoiding chilling damage under natural conditions.
Methods The cotton cultivars ‘Xinluzao 33’ (cold sensitive) and ‘Zhongmiansuo 50’ (cold tolerant) were used in this study. Gas exchange parameters, energy conversion and electron transmission of seedling leaves were determined under different levels and durations of low temperature stresses and subsequent recovery treatment. The adaptive capacity to light was also analyzed by developing photosynthetic light response curves of leaves under recovery treatment after 48 h of low temperature stresses.
Important findings The results showed that the values of net photosynthesis (Pn), stomatal conductance (Gs), stomatal limitation (Ls), intercellular CO2 concentration (Ci), maximum photochemical efficiency (Fv/Fm), maximal photochemical efficiency in light adaptation (Fv′/Fm′), actual quantum yield (ΦPSII) and relative electron transport rate (rETR) varied very little such that they reached the normal levels after being released from less-intense chilling stresses (15 °C or 24 h). In this situation, the damage of photosystem II (PSII) reaction center was reversible and the Pn was subjected to stomatal limitation. With decreasing temperature and treatment time, the parameters changed significantly and performed less well under recovery treatment in the two cotton cultivars. The limiting factor for Pn had changed from stomatal to non-stomatal, and the absorption, conversion of light energy, and electron transmission were severely inhibited. In addition, with a decrease in temperature, the maximum photosynthetic rate (Pnmax), the initial slope of photosynthetic light response curve (AQY) and the light saturation point (LSP) of cotton seedlings declined rapidly, and the light compensation point (LCP) and dark respiration (i.e. mitochondrial respiration; Rd), displayed an upward trend, indicating that the ability of radiation utilization decreased. Those results indicated that, low temperature stress decreased the adaptability to light environment, the activity of PSII reaction centers and photochemical electron transfer rate, inhibited pathways of photosynthetic electron transport, and reduced the CO2 fixation capacity, which led to the structural damage of photosynthetic apparatus and functional reduction in photosynthetic capacity. The cold tolerant cultivar could maintain higher photosynthetic rate by keeping higher photochemical electrontransfer, transport, and low-light utilization ability, and lower respiration, and by adjusting the reduction of Gs to be more rapid and sensitive, which could enhance the recovery capability and chilling adaptability.