| Low temperature is one of the abiotic stress factors that affect wheat growth and development,which often leads to yield loss and quality reduction of wheat.In the production practice,improving the cold resistance of wheat plants by applying exogenous compounds is one of the technical solutions to cope with low temperature disasters.Therefore,it is of great theoretical and practical significance to explore the effects of exogenous chemical substances on the growth of wheat and its mechanism of relieving low temperature injury.In this study,low temperature sensitive variety Kaimai 21 and resistant variety Zhoumai 27 were used as experimental materials to study the effects of exogenous spraying of choline chloride(CC)and trehalose(Tre)on the growth and development of wheat seedlings under low temperature.In addition,potted plant experiments were conducted to study the effects of spraying CC and Tre on wheat yield and the yield components under low temperature conditions.The main findings are as follows:1.After sprayed different concentrations of CC(100,300,500,700,1000 mg·L-1)and Tre(10,15,25,40,50 mmol·L-1)on wheat seedlings under low temperature,the relative electrical conductivity(REC)and malondialdehyde(MDA)content of the leaves were reduced to varying degrees compared to the control which was sprayed with fresh water;the optimum spraying concentration of CC and Tre was 500 mg·L-1 and 15 mmol·L-1,respectively.The morphological growth of Kaimai 21 and Zhoumai 27 seedlings with foliar spraying a concentration of 500 mg·L-1 CC was much better than the control sprayed with water at 48 h after low temperature treatment.Similarly,foliar spraying Tre at a concentration of 15 mmol·L-1,the seedling growth of Kaimai 21 was significantly better than that of the water control after 48 h low temperature treatment.It shows that spraying CC or Tre both increase the cold resistance of wheat to a certain extent.2.Compared with room temperature,the superoxide anion and MDA content in leaves of wheat seedlings increased at low temperature.However,the superoxide anion and MDA content in the leaves of seedlings could be decreased by spraying CC or Tre under low temperature conditions,and the decrease in Zhoumai 27 was more obvious.Meanwhile,the activities of catalase(CAT),superoxide dismutase(SOD)and peroxidase(POD)in leaves of seedlings sprayed with CC or Tre were all increased;proline and soluble protein contents were also enhanced.In addition,low temperature caused that the relative conductivity of wheat seedlings increased and the water content decreased.On the other hand,exogenous spraying of CC,Tre or CC+Tre could reduce the relative conductivity of leaves and increase the water content at low temperature.3.After potted wheat plants were treated with low temperature,the yield was significantly reduced,but foliar spraying with CC,Tre or CC+Tre could significantly increase the yield of wheat.Compared with the water spraying control,the increase rate of the three spraying measures was 23.15%,15.94% and 13.10% in turn,and the spraying of CC had a greater impact on the grain number per spike while spraying of Tre had a greater effect on the 1000-grain weight.In summary,the foliar spraying of CC or Tre significantly alleviated the wilting of seedling leaves caused by low temperature,enhanced the activity of antioxidant enzymes,reduced the damage of membrane lipid peroxidation of wheat leaves caused by low temperature,increased water content of leaves and promoted the accumulation of osmoregulatory substances.Besides,spraying CC or Tre reduced the adverse effects of low temperature on the yield of potted wheat growing in the field,thereby reducing the yield losses caused by low temperature. |
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