关键发育期干旱及复水过程对春玉米主要生理参数的影响

Effects of drought stress and subsequent rewatering on major physiological parameters of spring maize during the key growth periods

为深入了解玉米在关键发育期干旱条件下的耗水特征及致灾机理,对春玉米‘丹玉39’分别从拔节(T_1)和抽雄(T_2)期开始采用持续无补水方式进行干旱及复水试验,基于对叶和根水势、主要光合变量(净光合速率P_n、蒸腾速率T_r、气孔导度gs、胞间CO2浓度Ci)以及茎流速率(SF)的动态观测,研究各生理参数对干旱及复水过程的响应特征.结果表明:叶、根水势均与土壤湿度呈对数关系,不同时期干旱使二者都减小,对根水势的影响比叶水势提前,与拔节期相比,抽雄期叶水势的干旱响应偏早,根水势偏晚;叶水势在T_1处理复水后能得到恢复,但不能恢复到正常水平,T_2处理不能恢复;T_1处理的根水势对复水的响应比叶水势更快,且更接近于正常水平.P_n和T_r对T_2处理的响应快于T_1处理;复水后二者对T_1处理的恢复速度快于T_2处理,T_1和T_2处理P_n分别超过和达到正常水平,而T_r分别能和不能达到正常水平;T_r对T_1处理的响应早于P_n,二者对T_2处理的响应一致;各处理gs对干旱的响应与P_n一致;T_1处理的Ci与P_n趋势一致,T_2处理相反.各干旱处理SF比对照减小,在晴天比阴天响应明显,SF对T_2处理的响应比T_1处理敏感,在一定干旱水平后响应敏感性减弱;复水后SF比对照明显增大,T_2处理的增幅小于T_1处理.

For deeply understanding water consumption characteristics and disaster-causing mechanism of spring maize under drought stress,continuous no-water complementing for 40 days and subsequent rewatering treatments were conducted in jointing（ T1） and tasseling（ T2） stages of spring maize ‘Danyu 39＇. In the meantime,leaf and root water potential,main variables associated with photosynthesis including net photosynthetic rate（ Pn）,transpiration rate（ Tr）,stomatal conductance（ gs）,intercellular CO2 concentration（ Ci） and stem flow rate（ SF） were dynamically observed and the characteristics of their responses to drought and subsequent rehydration were investigated. The results indicated that leaf and root water potential,both presenting logarithm relationships with soil water content,decreased due to suffering from drought stress in different growth stages and the response of the former lagged behind that of the latter. At the same time,the response of leaf（ root） water potential to drought stress in tasseling stage was earlier（ later） than in jointing stage. For the response of rewatering,leaf water potential for the treatment T1（ T2） was（ not） able to recover to a certain extent,and could not reach the normal condition,while water potential of root was more responsive and closer to the normal level than that of leaf for the treatment T1. Furthermore,Pnand Trresponded more quickly to the treatment T2 than to the treatment T1. For subsequent rewatering after the treatment T1（ T2）,both Pnand Trrestored rapidly（ slowly） with the former exceeding（ returning） and the later being（ not） able to reach normal level. Meanwhile,the response of Trwas faster than that of Pnto the treatment T1 and they responded simultaneously to the treatment T2. The response of gsagreed with Pnto drought stress. Change trend of Cifor the treatment T1（ T2） was consistent（ opposite） with that of Pn. In addition,SFs for various drought treatments and their daily maximums decreased and appeared ahead of time to different extents,respectively. At the same time,the response of SF to drought stress was more sensitive for the treatment T2 than for T1 and on a clear day than on a cloudy day,but the sensibility of SF declined after drought reached a certain level. Besides,SFs for both the treatment T1 and T2 increased as a result of rewatering after drought and the increase for the treatment T1 was larger than that for the treatment T2.