盐胁迫下外源Si和Spd对番茄幼苗生长及光合荧光特性的影响

试验以"中杂9号"番茄(Solanum lycopersicum L.)为试验材料,采用水培法,研究外源硅(Na_2SiO_3,1.5 mmol·L~(-1))和亚精胺(Spd,0.25 mmol·L~(-1))对盐胁迫下(150 mmol·L~(-1)NaCl)番茄幼苗生长及光合荧光特性的影响。结果表明,盐胁迫下番茄幼苗生物量积累、根系活力、叶绿素含量及净光合速率均显著下降,其对光合作用的抑制以非气孔因素为主。外源Si和Spd均可缓解盐胁迫对番茄植株的伤害,具体表现为根冠比、叶片相对含水量、根系活力、光合作用增强。外源Si和Spd均可促进盐胁迫下番茄叶绿素积累,Si主要通过维持光合系统完整性提高叶片对光能利用效率;Spd则通过增加叶片气孔开放比例促进CO_2同化过程,增强其光合作用;Si和Spd复合处理下番茄生物积累量、叶片相对含水量及渗透势均达最大,但Fv/Fm、ФPSⅡ、ETR、qP却均呈不同程度降低,其对叶片光合特性的正调控效应较单施Si或Spd处理弱。综上所述,根施外源1.5 mmol·L~(-1)Na_2SiO_3和喷施0.25 mmol·L~(-1)Spd均可缓解NaCl胁迫伤害,Si和Spd主要通过促进盐胁迫下叶绿素合成,增强植株光合能力缓解胁迫伤害;Si及Spd复合处理则通过调节渗透系统提高番茄抗盐能力。

Effect of exogenous silicon and spermidine on growth and photosynthetic fluorescence characteristics of tomato seedlings under salt stress

The effects of exogenous silicon(Si) and spermidine(Spd) on growth and photosynthetic fluorescence characteristics in tomato were investigated, seedlings of tomato 'Zhongza 9' were subject to 150 mmol · L~(-1) NaCl salt stress with 1.5 mmol · L~(-1) Si and 0.25 mmol · L~(-1) Spd. The results showed that the biomass accumulation, root activity, chlorophyll content and Pn of tomato seedlings decreased significantly under salt stress, and the inhibition of tomato photosynthesis was mainly caused by non-stomatal factors. Both exogenous Si and Spd could alleviate the salt-induced reduction in plant growth, leaf relative water content, root activity, osmotic potential, chlorophyll content and photosynthesis. Exogenous Si and Spd could promote the accumulation of chlorophyll in tomato under salt stress. Si improved the utilization efficiency of light energy by maintaining the integrity of photosynthetic system, while Spd promoted the assimilation process of CO_2 by increasing the stomatal opening ratio of leaves and enhanced photosynthesis. The biomass accumulation, leaf relative water content, osmotic potential were increased the most, while the Fv/Fm, ФPSⅡ, ETR and q P decreased in varying degrees under the combined application of Si and Spd, and their positive regulatory effects on photosynthetic characteristics of leaves were weaker than those treated with Si or Spd alone. Comprehensive, the application Si and Spd could alleviate NaCl stress injury. Si and Spd alleviated stress injury mainly by promoting chlorophyll synthesis and enhancing plant photosynthetic capacity under salt stress, the combined treatment of Si and Spd could improve the salt tolerance of tomato through the regulation of osmotic system.