碱胁迫对大豆光合特性及内源激素含量的影响

Effects of alkaline stress on photosynthetic characteristics and endogenous hormone contents of soybean

用NaHCO3和Na2CO3混合溶液对25 d苗龄耐碱大豆品种吉育257和碱敏感品种东农63进行7 d胁迫处理,通过分析混合碱胁迫对不同大豆品种光合作用、叶绿素荧光参数和内源激素含量的影响,探讨大豆激素与光合作用的作用机制,为耐碱品种的选育和盐渍土地的有效利用提供理论依据。结果表明:混合碱胁迫后,吉育257叶片SPAD值、光化学猝灭系数(qP)、赤霉素(GA)含量、生长素(IAA)含量和细胞分裂素(CTK)含量均呈先升高后降低的趋势,东农63呈持续降低趋势;两品种净光合速率(Pn)均低于对照,脱落酸(ABA)和ETH含量均呈持续升高趋势。大豆可以通过调节自身CTK和ABA含量来调控自身气孔的开闭状态。30 mmol/L混合碱胁迫对吉育257各性状有一定的促进作用,对东农63各性状的抑制不明显,大豆植株光合速率下降的原因可能是气孔限制或内源激素调节降低了植株自身的生理需求。两品种在60 mmol/L混合碱浓度下均受到不同程度影响,耐碱性品种所受影响小于敏感性品种;90 mmol/L混合碱浓度下两品种均受到严重影响,其中光合速率下降的原因可能是非气孔限制和激素合成能力下降。60 mmol/L混合碱胁迫浓度可能为大豆耐碱性临界点,该浓度下,吉育257的防卫能力明显优于东农63。

The mixed solution of NaHCO3 and Na2CO3 was used to treat 25-day-old alkali-tolerant soybean variety Jiyu 257 and alkali-sensitive variety Dongnong 63 for seven days.The effects of mixed alkali stress on photosynthesis,chlorophyll fluorescence parameters and endogenous hormone content of different soybean varieties were analyzed.Moreover,the action mechanism of soybean hormones and photosynthesis was discussed to provide theoretical basis for the selection of alkali resistant varieties and the effective utilization of saline land.The results showed that the chlorophyll meter(SPAD)value,photochemical quenching coefficient(qP),gibberellic acid(GA)content,indoleacetic acid(IAA)content and cytokinin(CTK)content in leaves of Jiyu 257 increased first and then decreased,while those indicators of Dongnong 63 continued to decrease.The net photosynthetic rate(Pn)of the two varieties was lower than that of respective control,and the abscisic acid(ABA)and ethylene(ETH)tended to increase continuously.Soybean could regulate the opening and closing states of their stomata by adjusting the contents of CTK and ABA.The mixed alkali(30 mmol/L)stress had a certain promotion effect on various traits of Jiyu 257,but it had no obvious inhibition on traits of Dongnong 63.The reason for the decrease in photosynthetic rate of soybean plants might be the limitation of stomata or the regulation of endogenous hormones,which further reduced the physiological needs of the plants.The physiological traits of two soybean varieties were affected in different degrees under mixed alkali(60 mmol/L)stress,and the influence of alkali-tolerant was less than that of alkali-sensitive variety.The physiological traits of the two soybean varieties were seriously affected under the treatment of 90 mmol/L mixed alkali,and the decrease of photosynthetic rate may be caused by the decrease of hormone synthesis ability and non-stomatal limitation.When the concentration of mixed alkali was 60 mmol/L,soybean might reach the critical point of alkali tolerance.At this concentration,the defense ability of Jiyu 257 was obviously better than that of Dongnong 63.