The Alleviation Effect Of Spraying Chitosan On The Phytotoxicity Of Millet Under MCPA-Na Stress

Weeds are one of the main factors limiting the stable and high yield of millet,and millet is very sensitive to herbicides.Improper application can cause phytotoxicity to crops,which can reduce yield in mild cases,and can cause crop death in severe cases.Chitosan is a non-toxic and harmless polymer anti-stress active agent,which plays an important role in the response of plants to adversity stress.In this study,Zhangzagu No.10 was used as the test material,and different concentrations of MCPA-Na(0,1605 and 3210 g/hm2)and different concentrations of chitosan were sprayed at the five-leaf stage of millet.0,50,100,150 mg/L)7 days after compounding and spraying different concentrations of MCP A-Na,spraying two treatments with different concentrations of chitosan,and setting the control of each concentration of MCPA-Na and chitosan.To study the effects of the two treatments on the safety,photosynthetic physiology and production performance of millet under different concentrations and different application times,and to clarify the optimal dose of chitosan on the phytotoxicity mitigation effect of millet under MCPA-Na stress.The main research results are as follows :1.Spraying MCPA-Na has an inhibitory effect on the plant height and leaf area of the millet at the seedling stage.Whether it is a combination of MCPA-Na and chitosan or spraying chitosan 7 days after MCPA-Na,the difference is alleviated.The degree of inhibition of MCPA-Na,where the plant height and leaf area of the compound have a higher relief efficiency than that of 7 days after the drug.The plant height and leaf area of the compound paired millet were as follows: when spraying different concentrations of MCPA-Na,the chitosan concentration was as follows: J2>J3>J1.When MCPA-Na was sprayed with chitosan 7 days later,the performance was: J3>J2>J1.2.Spraying MCPA-Na at the seedling stage will inhibit the dry weight(DW)of millet,especially the high concentration of MCPA-Na,while spraying chitosan through stems and leaves can relieve the dry weight.Whether it is a combination of MCPA-Na and chitosan or spraying of chitosan 7 days after spraying MCPA-Na,the performance is best at 100-150 mg/L.In the maturity period,the dry matter accumulation quality of each organ is shown as follows: ear>stem>leaf.During the compounding treatment,the chitosan concentration was compounded with the maximum at J2 and MCPA-Na;when MCPA-Na was treated 7 days after the treatment,there was a maximum at J3.3.The yield and composition indexes of MCPA-Na and chitosan compound treatment are higher than that of MCPA-Na treatment alone.The compound of MCPA-Na and chitosan J2 at each concentration has the maximum value compared with the control,and M0J2 is higher than M0J0.14.74%,M1J2 was 17.51% higher than M1J0,M2J2 was 23.32% higher than M2J0,and M2J2 treatment increased the most.The yield of chitosan sprayed 7 days after MCPA-Na showed a gradual increase with the increase of chitosan spray concentration.M1J2 increased by 17.73% compared with M1J0,and M2J3 increased by 15.93% compared with M2J0.4.Spraying chitosan is beneficial to the antioxidant enzyme activity of millet leaves at the seedling stage and reduces the content of malondialdehyde in millet leaves.During the compounding treatment,with the changes of MCPA-Na and chitosan concentration,the SOD activity of millet leaves showed a trend of increasing first and then decreasing at different measuring times.With the increase of MCPA-Na concentration,the content of malondialdehyde in the millet leaves showed a gradual increase,and with the increase of the concentration of chitosan,the content of malondialdehyde first decreased and then increased;7 days after treatment,the concentration of chitosan had the maximum value on SOD activity of millet leaves at J3.The interaction of MCPA-Na(A),chitosan(B)and post-drug time(C)on SOD activity,the two different treatments have different performances.The interaction between AB and BC was significant during the compound treatment;the interaction between AB and AC was significant when treated 7 days after the drug.In the two treatments,MCPA-Na and chitosan showed significant interaction.5.Chlorophyll a and chlorophyll b of millet leaves increased with the spraying concentration of MCPA-Na.Under the compound treatment,different chitosan concentrations showed a trend of first increasing and then decreasing the photosynthetic pigment content of millet;7 days after treatment Bottom,its photosynthetic pigment content showed a gradual increase trend.The photosynthetic characteristics of the two treatments both increased with the growth period.The net photosynthetic rate,stomatal conductance,and transpiration rate showed a trend of first increasing and then decreasing,and the intercellular CO2 concentration(Ci)showed a trend of first decreasing and then increasing.