草甘膦对大豆光合特性日变化的影响

Effect of Glyphosate on Diurnal Variation of Photosynthesis in Leaves of Soybean Glycine max (L.) Merr

为探明草甘膦对普通大豆光合特性日变化的影响,在大田条件下,采用随机区组设计,研究了不同剂量草甘膦对晋大75净光合速率(Pn)、蒸腾速率(Tr)、水分利用效率(WUE)、气孔导度(Gs)和胞间CO2浓度(Ci)日变化的影响。结果表明:(1)在未喷施草甘膦情况下,晋大75的Pn和Gs日变化呈双峰曲线,峰值分别出现在10:00时、16:00时和10:00时、14:00时左右;Tr呈单峰曲线,峰值出现在14:00时左右;WUE在上午和傍晚较高,14:00时左右最低。(2)喷施草甘膦后,晋大75光合特性的日变化趋势总体与未喷药前相似。Pn随草甘膦剂量的增加呈降低趋势,当剂量达到0.92 kg.hm-2时严重抑制Pn。0.46 kg.hm-2的草甘膦促使Tr的峰值提前到12:00时出现,而0.92kg.hm-2处理却使Tr日变化呈双峰曲线。12:00时以前(包含12:00时),除低剂量(0.46 kg.hm-2)的草甘膦可提高晋大75的Tr和Gs外,其他各剂量在一天中均降低了其Tr和Gs。草甘膦增加了晋大75的Ci,而>0.92 kg.hm-2的草甘膦却降低了其WUE。

Random complete block design was used to research the different dosages of glyphosate on diurnal variation of photosynthetic characteristics in leaves of soybean（Jinda 75） in the field.The results showed that：（1） The trend of diurnal variation of net photosynthetic rate（Pn） and stomatal conductance（Gs） in soybean leaves was a two-peak curve,the peak appeared at about 10：00 and 16：00,separately.The trend of diurnal variation of transpiration rate（Tr） was a one-peak curve,the peak appeared at about 14：00.The water use efficiency（WUE） was higher in the morning and evening,and the lowest at 14：00.The intercellular CO2 concentration（Ci） of soybean was the highest at 6：00,and changed like ＂wave＂ with time.（2） The trend of diurnal variation of net photosynthetic characteristics in soybean leaves treated with glyphosate was similar to the control.Pn decreased with increasing of glyphosate dosage,and dropped significantly when glyphosate dosage ≥ 0.92 kg·hm^-2.The Tr peak time of Jinda 75 was brought forward to 12：00 by glyphosate at 0.46 kg·hm^-2,while glyphosate at 0.92 kg·hm^-2 made the Tr trend two-peak curve.Glyphosate inhibited Tr and Gs of soybean except glyphosate at 0.46 kg·hm^-2 promoted Tr and Gs before 12：00（including 12：00）.Ci of soybean increased with increasing of glyphosate dosage,and glyphosate〉 0.92 kg·hm^-2 reduced WUE of Jinda 75.