Physiological mechanism of flag leaf on maintaining high photosynthetic rate in the afternoon during the grain filling stage in wheat under drought
In order to study the mechanism of how the flag leaf maintained high photosynthetic rate in the afternoon during the grain filling stage of wheat under drought,an experiment with two winter wheat culti-vars and four water levels was conducted under the condition of rainproof pond cultivation in 2018-2021.The two winter wheat cultivars were'Jinmai47'('JM47',strong drought resistance)and'Yanzhan4110'('YZ4110',weak drought resistance).The four water treatments include severe drought(W1),moderate drought(W2),mild drought(W3),suitable water supply(W4).The net photosynthetic rate(Pn),relative wa-ter content(RWC),antioxidant properties and osmotic regulators in flag leaves from 14:00 to 16:00 during the early(EGFS),medium(MGFS),and medium and later(MALGFS)grain filling stage and the grain yield at maturity were investigated.The results showed that drought decreased the Pn in flag leaf in the afternoon during the grain filling stage and grain yield in wheat,and on the whole the Pn and grain yield of'JM47'were significantly higher than that of'YZ4110'.Averaged across the three years,compared with W4,the physiological characteristics of flag leaves in the afternoon during the grain filling stage were as follows:RWC,peroxidase(POD)activities,and catalase(CAT)activities decreased,malondialdehyde(MDA),pro-line(Pro)content and soluble sugar(SS)content increased,and the amplitude of'JM47'was better than that of'YZ4110'.Compared with'YZ4110',the RWC,POD activity,SS content in flag leaves of'JM47'in the afternoon during MGFS and the RWC,POD activity,CAT activities and Pro content in flag leaves in the af-ternoon during MALGFS were significantly increased under drought,while the MDA content in flag leaves in the afternoon during MGFS and MALGFS was significantly decreased.The results of correlation analysis showed that,in the afternoon during the grain filling stage,the Pn in flag leaves was positively correlated with RWC,POD activities and CAT activities,but significantly negatively correlated with Pro,SS content and MDA content,except for the CAT activities and SS content for'JM47'and the CAT activities for'YZ4110'during EGFS and the CAT activities in'JM47'during MGFS.In conclusion,drought stress reduced the Pn in flag leaves in the afternoon during the grain filling stage.However,'JM47'with strong drought re-sistant could maintain the higher RWC,POD activities,CAT activities,and Pro content,SS content,and a lower MDA content in flag leaves in the afternoon,which may be the major physiological basis of'JM47'for maintaining a high flag leaf Pn in the afternoon during the grain filling stage.
droughtin the afternoon during the grain filling stagephotosynthetic ratephysiological char-acteristicsgrain yield
万方数据
维普
