复水前后冬小麦光合生理特征对保水剂用量的响应

Response of Photosynthetic Parameters of Winter Wheat before and after Re-watering to Different Rates of Water-retaining Agent

为探明干旱胁迫复水前后作物水分消耗过程中冬小麦生理特征对保水剂用量的响应及作用机理,采用盆栽试验以不施保水剂为对照,测定了保水剂不同用量(无保水剂、27 mg/kg、54 mg/kg、81 mg/kg)条件下,复水前后的土壤含水率及光合参数的持续变化特征。结果表明:干旱胁迫时,保水剂降低了小麦叶片光合速率、蒸腾速率、气孔导度,提高了水分利用效率。复水后,对照的光合速率、蒸腾速率及气孔导度仍较高,保水剂处理依次为:54 mg/kg、81 mg/kg、27 mg/kg。而当土壤含水率降至田间持水量的55%左右时,各处理光合参数依次为:27 mg/kg、CK、54 mg/kg、81 mg/kg;水分利用效率依次为:81 mg/kg、27 mg/kg、CK、54 mg/kg。随保水剂用量的增加,小麦生物量增加,但81 mg/kg处理显著高于对照。同时,保水剂会影响叶片光合参数之间的相关性,其中,小麦气孔导度与光合速率、蒸腾速率的相关性以54 mg/kg处理最紧密,依次为81 mg/kg处理、对照,27 mg/kg处理最差。而气孔导度与土壤含水率、水分利用效率及光合速率与土壤含水率、蒸腾速率、水分利用效率的相关性强弱从大到小的处理依次为:81 mg/kg、54 mg/kg、CK、27 mg/kg。说明小麦叶片光合参数对保水剂的响应以54 mg/kg与81 mg/kg处理最显著。

In order to ascertain the response of photosynthetic parameters of winter wheat during the course of soil water consuming from drought stress to re-watering to different dosage of water-retaining agent and make clear the acting mechanism of water-retaining agent,the pot experiment was employed and water-retaining agent was added to the soil at the following rates： 0mg/kg,27mg/kg,54mg/kg,and 81mg/kg.The results indicated that photosynthetic rate（Pn）,transpiration rate（Tr）,and stomatal conductance（Gs） of wheat were decreased,but water use efficiency（WUE） was increased after the application of water-retaining agent under drought stress.After re-watering,Pn,Tr,and Gs of CK were still higher,and those of water-retaining agent,from high to low,were as the following： 54mg/kg,81mg/kg,27mg/kg.When soil moisture content fell to about 55% of field capacity,the photosynthetic parameters of each treatment were ranged in order from the higher to the lower ones as the following： 27mg/kg,CK,54mg/kg,81mg/kg.WUE of different treatments were rank as the following： 84mg/kg,27mg/kg,CK,54mg/kg.And with the increase of the amount of water-retaining agent,wheat biomass increased,but those of 81mg/kg of water-retaining agent were significantly high compared with other treatments.Meanwhile,water-retaining agent had an effect on the relations among photosynthetic parameters of winter leaves.The correlations between Gs and Pn and Tr of wheat applied with 54mg/kg of water-retaining agent were the most closely connected,next were the treatments with 81mg/kg,CK and 27mg/kg of water-retaining agent respectively.However,the connections of correlations between Gs and soil,WUE and those between Pn and soil water,Tr,and WUE all showed in the following order： 81mg/kg,54mg/kg,CK,27mg/kg.It could be concluded that the treatments with 54mg/kg and 81mg/kg of water-retaining agent had significant effect on the correlations between photosynthetic parameters of wheat leaves.