NaCl胁迫对苦豆子幼苗光合机构及生物量积累的影响

Effects of NaCl Stress on Photosynthetic Apparatus and Biomass Accumulation of Sophora alopecuroides Seedlings

该研究通过测定盐生药用植物苦豆子幼苗气体交换、叶绿素荧光参数及生长指标,研究了中度(200mmol/L NaCl)和重度(400mmol/L NaCl)盐胁迫对其生长特性的影响,探讨盐生植物对盐化环境的生理响应机制。结果显示:(1)中度盐胁迫1d后,苦豆子幼苗光合速率(P_n)、气孔导度(G_s)、蒸腾速率(T_r)及胞间二氧化碳浓度(C_i)显著低于对照,随着胁迫时间延长,P_n下降显著,而气体交换参数降低不明显,C_i值甚至有上升趋势;重度盐胁迫处理1d后,苦豆子气体交换值出现了显著降低,随着胁迫时间延长,降低程度增大;中度盐胁迫导致苦豆子光合速率出现下降的原因是由气孔因素和非气孔因素共同作用的结果,而重度盐胁迫下,Pn的下降主要是非气孔因素引起的。(2)处理1d后,相对于对照组,中度和重度盐胁迫下的苦豆子幼苗最大光化学效率(F_v/F_m)、光化学猝灭系数(qP)、实际光化学效率(Φ_(PSⅡ))出现了不同程度的降低,而重度盐胁迫下降低更加显著;处理5d后,中度盐胁迫荧光参数变化不明显,但重度盐胁迫处理下降低显著。(3)随着胁迫程度的加重,幼苗含水量及生长指标(株高、根长、干重)降低幅度加大,以致严重抑制了植株生长。研究表明,盐生植物苦豆子对盐胁迫的耐受性也有一定限度,其在200mmol/L NaCl胁迫下植株光合作用受到轻微抑制,但能维持正常生长,而在400mmol/L NaCl胁迫下光合生理受到严重抑制,且随着胁迫时间的延长,受到伤害程度加重,甚至死亡。

Effects of moderate(200mmol/L NaCl)and severe(400mmol/L NaCl)salt stress on the growth characteristics of Sophora alopecuroides were studied by measuring gas exchange,chlorophyll fluorescence parameters and growth indexes.The results showed:(1)one day after moderate salt stress,significant decreases were measured in photosynthetic rate(P n),stomatal conductance(G s),transpiration rate(T r)and intercellular carbon dioxide concentration(C i)of S.alopecuroides seedlings.Five days after moderate salt stress,slight decrease occurred in P n while slight increase was measured in C i.However,one day after severe stress,significant decreases were measured in gas exchange of S.alopecuroides,with it getting worse along with longer time stress.The reason for the decrease of photosynthetic rate of S.alopecuroides was due to the combined effect of stomatal factors and non-stomatal factors.The decrease of P n was mainly caused by non-stomatal factors under severe salt stress.(2)The maximum photochemical efficiency(F v/F m),photochemical quenching coefficient(q P),actual photochemical efficiency(ΦPSⅡ)decreased in different levels.The decrease was more significant in severe salt stress than in moderate salt stress treatment.The change of fluorescence parameters was not obvious under moderate salt stress,while it was significant under severe salt stress along with the prolongation of stress time.(3)With the aggravation of salt stress,water content and growth indicators(plant height,root length,dry weight)were markedly decreased,leading to a serious inhibition in plant growth.The results showed that the tolerability of halophytes to salt stress was also limited.The growth of S.alopecuroides was slightly inhibited under200mmol/L NaCl stress while it was seriously damaged under400mmol/L NaCl stress.