盐胁迫对不同基因型海岛棉光合作用及荧光特性的影响

Effects of NaCl Stress on the Characteristics of Photosynthesis and Chlorophyll Fluorescence at Seedlings Stage in Different Sea Island Cotton Genotypes

【目的】研究盐胁迫对不同基因型海岛棉功能叶光合作用及叶绿素荧光参数的影响,为海岛棉栽培管理、抗性筛选提供理论参考。【方法】以两种海岛棉基因型—新海21号(盐敏感型)和新海28号(耐盐型)为材料,采用水培法,从3叶期开始进行NaCl处理(NaCl浓度为0、50、100、150、200、250mmol·L-1),研究盐胁迫下海岛棉生长、光合作用及叶绿素荧光参数的变化。【结果】研究表明,低浓度盐分(NaCl≤50mmol·L-1)可促进耐盐型新海28号的生长,增加鲜干重,提高叶绿素总量、叶绿素a和b的含量,使PSⅡ光化学量子效率(ΦPSⅡ)、光化学猝灭系数(qP)和非光化学猝灭系数(NPQ)上升,实现单叶净光合速率(Pn)增加;高浓度盐分(NaCl>50mmol·L-1)可抑制两个基因型的生长,导致叶片净光合速率(Pn)、气孔导度(Gs)、Fv/F0、Fv/Fm、PSⅡ光化学量子效率(ΦPSⅡ)、光化学猝灭系数(qP)均下降,非光化学猝灭系数(NPQ)和胞间CO2浓度(Ci)的提高。【结论】盐胁迫下,随盐浓度增加,引起海岛棉光合速率下降的原因逐渐由气孔限制转向非气孔限制,光合参数、叶绿素荧光参数的变化与基因型抗性及盐浓度密切相关。

[Objective] The effects of NaCl stress on photosynthesis and chlorophyll fluorescence of sea island cotton genotypes were studied. [Method] Two sea island cotton varieties, Xinhai 21 （XH21, NaCl sensitive genotype） and Xinhai 28 （XH28, NaCl tolerant genotype） were selected, and germinated in full nutrient solution. NaCl was added into solution at 3-leaf full expanding stage and NaCl concentration levels at 0, 50, 100, 150, 200 and 250 mmol·L^-1 respectively. Photosynthetic parameters, chlorophyll fluorescence variation were investigated after 30 d. [Result] The results showed that, under low NaCl concentration stress, the growth of the plants, fresh weight, biomass, chlorophyll content were enhanced, ΦPSⅡ, qP, NPQ were increaseed as well, all these increased Pn of leaves in tolerant genotype Xinhai 28. Under high NaCl stress, plant growth restrained significantly in both genotypes, Pn, Gs, Fv/F0, Fv/Fm, ΦPSⅡ and qP were reduced, while NPQ and Ci increased. [Conclusion] The decrease of net photosynthetic rate was considered as a result of no-stomatal restriction turning stomatal restriction along with NaCl concentration increase. Photosynthetic parameters and chlorophyll fluorescence were highly correlated with genotypes＇s salt tolerance and salt concentration.