干旱胁迫下决明属植物光合生理特性日变化研究

Diurnal Changes of Photosynthetic Physiological Characteristics in Cassia under Drought Stress

以4种决明属植物草决明、望江南、伞房决明、双荚决明为材料,采用盆栽控水试验,设置轻度干旱、重度干旱和正常灌水处理,研究了干旱胁迫对4种决明属植物的叶绿素含量、光合作用参数日变化的影响。结果显示:1)干旱胁迫导致4种决明属植物的叶绿素含量下降,望江南的下降幅度最小,说明望江南在水分减少的情况下仍具有较高的光合作用能力,双荚决明的降幅最大,说明其光能吸收、转换和传递能力较弱,不能够维持一定水平的光合作用,抗旱性较差。2)干旱胁迫下,该属植物的P_n、G_s、T_r日变化从具有明显的峰值到峰值不明显到无峰值,且P_n、G_s、C_i、T_r均在下降,表明水分亏缺会造成该属植物光合作用减弱,而望江南和伞房决明都保持了优良的适应性,其中望江南的自身调节更为突出,双荚决明则随着干旱程度的加剧表现出光合作用几乎停止的状态。3)干旱胁迫下,4种决明属植物的G_s和T_r峰值均在12:00左右,C_i不随着G_s的降低而减小,说明该属植物光合作用降低的原因主要是非气孔限制的结果。

Taking four species of Cassia C. obtusifolia,C. occidentalis,C. corymbosa,C. bicapsularis as materials,using pot water control experiment,setting light drought,severe drought and normal irrigation treatments,the effect of drought stress on the diurnal changes in chlorophyll content and photosynthesis in the four species.The results showed： 1） The drought stress resulting in a decline in the chlorophyll content of the four species of Cassia,the decline in C. occidentalis was the smallest,which suggested that C. occidentalis still had high photosynthetic capacity under the condition of water cut.The decline in C. bicapsularis was the maximum,indicating that its absorption,conversion and transmission of light energy was weak,and not able to maintain a certain level of photosynthesis,which resulted in poor drought resistance.2） Under drought stress,the diurnal variation of Pn,Gsand Trshowed a trend from an obvious peak to an unobvious peak to nopeak,and Pn,Gs,Ci,Trwere all in decline,indicating that water deficit would weaken photosynthesis in Cassia. C. occidentalis and C. corymbosa maintained excellent adaptability,C. occidentalis＇ showed good self regulation,photosynthesis almost stopped in C. bicapsularis along with the intensification of drought.