Effect Of Foliar Fertilizer On Cold Resistance And Yield Increase Of Double-Cropping Rice

The late spring cold and cold dew wind have brought serious harm to the yield of double cropping rice in Hunan.Field experiments were carried out in Hengyang county,Hunan province with early rice variety Zhongjiazao 17 and late rice variety H You 518 as materials.Effects of the application periods(early rice:7 days before transplanting,A1;on the day of transplanting,A2;7 days after transplanting,A3;7 days before transplanting+7days after transplanting,A4;late rice:booting stage,C1;full heading stage,C2;7 days after full heading,C3;booting stage+full heading stage,C4)and spraying concentrations(0.75kg/hm~2,B1(early rice)and D1(late rice);1.125 kg/hm~2,B2(early rice)and D2(late rice))of leaf fertilizer Zhuanggubao on yield and its components,tillering dynamics,leaf area and dry matter accumulation dynamics,protective enzyme activity and malondialdehyde content of double cropping rice and delayed sowing late rice,so as to clarify the suitable spraying period and concentration of Zhuanggubao and provide technical support for the cold resistant and stable yield cultivation of local rice.The main results are as follows:(1)The treatment of Zhuanggubao could increase the yield of rice.Yield was higher in A4B2,A4B1 and A2B2 treatment in early rice,which increased by 10.92%、9.42%and5.78%respectively compared with CK.Yield was higher in C4D2,C4D1 and C3D2treatment in late rice,which increased by 12.57%,10.26%and 8.24%respectively compared with CK.The analysis of output value and cost showed that the treatment with the highest economic benefit was A2B2 for early rice and C3D2 for late rice.Correlation analysis showed that the ways of yield increasing of early and late rice were slightly different,early rice mainly increased the number of effective panicles and seed setting rate,while late rice mainly increased the grain number per panicle,number of effective panicles and seed setting rate.(2)Zhuanggubao treatment could increase the total leaf number,leaf area index,aboveground dry matter weight and chlorophyll content of rice,and the first three generally increased with the increment of application times and concentration of Zhuanggubao.Among the Zhuanggubao treatments,A4B2 treatment had the best improving effects for early rice and C4D1 treatment was the best for late rice.(3)The application of Zhuanggubao significantly increased the activities of leaf protective enzymes(SOD,POD and CAT)and significantly reduced the content of malondialdehyde in leaves from booting stage to mid-filling stage of late rice,and the treatment of spraying twice of Zhuanggubao(C4 treatment)had the best effect.(4)The experiment of sowing date(June 21,July 1,July 11)showed that delaying sowing resulted in significant yield reduction of late rice,but spraying Zhuanggubao could significantly increase the yield of late rice at each sowing date(an increase of 12.57%-22.65%),and the later sowing date,the greater increase of yield and protective enzyme activity,and the greater decrease of malondialdehyde content.It can be seen that the more low temperature was encountered,the more obvious the effect of cold resistance and yield increase.It can be seen that leaf fertilizer Zhuanggubao realized the cold resistance and stable yield for double cropping rice by increasing the activity of leaf protective enzymes,reducing the content of malondialdehyde in leaves and improving the growth and development of rice.Comprehensive yield and economic benefits,spraying Zhuanggubao 1.125 kg/hm~2on the day of transplanting for early rice and 1.125 kg/hm~2on the 7th day after full heading stage of late rice is the best treatment.