Regulation And Application Of Amaranthus Retroflexus Extract On Heat Tolerance Of Wheat

High temperature stress seriously affected the yield and quality of wheat.The application of plant growth regulator in wheat filling stage to improve its heat resistance stress has attracted much attention.Our previous study found that A.retroflexis extract could induce heat resistance in wheat.In order to further clarify the regulatory effect of A.retroflexus extract on wheat heat resistance,in this paper,the effects of A.retroflexus extract on the morphological and physiological indexes of wheat seed,seedling stage and filling stage under heat stress were studied.The effects of coating treatment of A.retroflexus extract on the morphological indexes of heat-resistant and heat-sensitive wheat varieties were also evaluated.To provide theoretical support for the subsequent use of extracts.The main results are as follows:（1）Wheat seed soaking with A.retroflexus root extract,which can obviously induce seed heat,and water with 60%methanol extract activity;The tray experiment showed that the heat resistance of wheat seedlings could be induced by 500μg/ml soaking under different soil water content（20%,30%and 40%）,and the most significant was 20%soil water content,the morphological indexes of wheat seedlings were significantly higher than those of control group.（2）Under high temperature stress,A.retroflexus extract was sprayed into roots and stem leaves,the activities of antioxidant enzymes（SOD,POD and CAT）were increased,the contents of soluble sugar and proline were increased,and the contents of relative electrical conductivity and malondialdehyde（MDA）were decreased,which alleviated the membrane lipid peroxidation of wheat seedlings.（3）Under high temperature stress,spraying 1000μg/ml extract can not only increase the contents of osmotic regulatory substances（soluble sugars and free amino acids）in wheat flag leaves,but also improve the activities of antioxidant enzymes in wheat flag leaves,and reduce the plasma membrane permeability,H₂O₂and MDA contents in wheat flag leaves,maintaining the integrity of cell membrane structure.The photosynthesis of wheat flag leaf was enhanced,the filling and ripening time of wheat was prolonged,and the theoretical yield was increased.（4）The coating treatment of A.retroflexus extract could induce the heat resistance of wheat seeds,and the coating treatment of 2.0%and 2.5%extract was the best.The germination vigor and morphological indexes of wheat seeds were also significantly improved for heat-resistant varieties（Zhongmai 578 and Zhengmai 7698）and heat-sensitive varieties（Yannong 999 and Zhengmai 9023）,and the heat-sensitive varieties were significantly better than heat-resistant varieties.