Measurement For Kernel Natural Dry-down Rate In Maize (Zea Mays L.) And Its Application In The Germplasm Screening

Maize is one of the main food crops in China and played an important role in ensuring national food security.However,maize kernels had higher moisture content after harvest in Chinese northeast,which would increase the costs of storage and processing and had become the main bottleneck in the advance of agricultural mechanization.This paper established the protocol for the identification of kernel natural dry-down rate in maize by the combination of electrophysics detecting and oven drying and screened out elite germplasm.It would quicken the advance of cultivating new varieties,propel the realization of agricultural mechanization and the development of maize industry.The main results were as follows:1.Based on 132 core inbred lines and 36 commercial hybrids,the protocol for the identification of kernel natural dry-down rate in maize was established,which included measuring stage,measuring tactics and assessment criterion.(1)The beginning point of the measurement for inbred lines and hybrids is 35 days and 45 days after pollination,respectively.(2)Compared with oven drying,electrophysics detecting could have non-destructively,easy and rapid merits.(3)The assessment criterion was divided into three grades.The kernel natural dry-down rate was described by high,medium and low.The three grades of KDR for inbred lines were KDR? 1.37%/,0.55<KDR<1.37%/d and KDR?0.55%/d.The three grades of KDR for hybrids were KDR?0.78%/,0.43<KDR<0.78%/d and KDR?0.43%/d.2.The correlation between kernel natural dry-down rate(KDR)and twenty related traits was analyzed.The results showed that there was negative correlation between KDR and other nineteen traits besides the interval between pollination and physiological maturity.The KDR was highly significantly negative correlated with the seedling-pollination interval,the seedling-anthesis interval,the seedling-silking interval,plant height,ear height,ear diameter,grain weight per ear,100-kernels weight.The KDR was significantly negative correlated with ear length,row number per ear,kernel number per line,ear weight,cob diameter.The KDR was non-significant negative correlated with the silking-anthesis interval,the pollination-harvest interval,tassel length,tassel branch number,bract number,bract length.3.Based on the established protocol for the identification of kernel natural dry-down rate in maize,the KDR of 298 inbred lines and 42 hybrids was measured.Eighty-two inbred lines with high KDR were obtained,which included A624,M14,yuBL3,ying64,luozao4,ji69,ji818,da23,A634Ht,ji994,78599S1,ye502,etc.Nine hybrids were obtained,which included jinongda889,jiudan318,jinongda935,deyu919,demeiyal,demeiya2,demeiya3,denghai605,wd4436,etc.4.The KDR of 43 inbred lines for 2015 and 2016 was compared.The KDR of the same inbred line in different years had a degree of difference.The lines for the smaller variation in different years were the ideal parents applied to create varieties with high KDR.