Corn Stalk Sugar Content With The Force And Its Correlation With Yield And Agronomic Traits

The demand of silage feed is increasing with the rapid development of livestock in our country. Silage corn, characteristic of high biological yield and good feed conversion, is an important feed source of grass-feeding livestock. At present, a total of 1.667 million hm2 of silage corn can meet the needs of grass-feeding livestock per year in our country. In the next few years, the demand for silage corn will reach 4 million hm2 per year in our country. The quality of silage corn improvement is necessary. High sugar content of stalk will help for further improving the quality of corn silage and palatability of feed. Additionally, high-sugar corn stalks after harvest can be used to extract the fuel ethanol, which can enhance the corn stalk's comprehensive and high-value utilization.Sugar contents in one hundred and fifty one corn inbred lines stalk were evaluated in this study. According to the results of screening,seven corn inbred lines were used as parents to produce 21 combinations by p(p-1)/2 diallel crossing model. The combining ability in stalk sugar content and correlation between stalk sugar content and yield, major agronomic characteristics were investigated in this study. Results were as followings:(1) The sugar content in stalk ranged from 3.5% to 16.9%, 65 out of 151 inbred lines (43.1%) had sugar content up to 10%. These inbred lines might be useful for improvement of sugar content of hybrid stalk. All the tested inbred lines could be divided into three types according to their sugar content in stalk by using cluster analysis method. Type III contained 22 inbred lines with high sugar content of stalk (Brix=12.3～16.9), which might be pivotal to increase sugar content of corn hybrid stalk.(2) The sugar content of corn stalk was controlled by both the additive and non-additive genetic effect. The non-additive genetic effect played an important role in the corn stalk sugar content inheritance. Seventy-five percent of variation of sugar content of corn stalk was controlled by genetic factors. However, the narrow sense heritability of sugar content of corn stalk was relatively high, up to 0.552. Thus, the sugar content of corn stalk can be selected in early generation. The general combining ability and special combining ability of stalk sugar content were significantly different. The inbred line Y53-164 might be an ideal material for silage corn breeding.(3) Phenotypic correlation analysis showed that the sugar content of corn stalk had a significant positive correlation with the area of three ear-leaf (ATEL) and area of the first leaf above the ear(AFLAE)and ear leaf area(ELA)and area of the first leaf down the ear(AFLDE)at P<0.05 or P<0.01. The results of partial correlation and stepwise regression analysis revealed that the principal characteristics for the sugar content of corn stalk were ear length (X1), kernels per row (X4), seed weight per plant (X5), days from sowing to heading (X7), days from to silking (X8), plant height (X9), ear height (X10) and ear leaf area (X13). Of eight characteristics, in addition to the stalk sugar content had a correlation with kernels per row at P=0.0562, the stalk sugar content had a significant correlation with the other seven characteristics at P<0.05 or P<0.01. Three characteristics, which were kernels per row, days from sowing to heading and plant height, had a negative correlation with stalk sugar content. Five characteristics, which were ear length, grain weight per plant, days from sowing to silking, ear height and ear leaf area had a positive correlation with stalk sugar content. By stepwise regression analysis, the relationship between stalk sugar content and 8 characteristics were modeled using the following linear equation: Y=4.71753+0.5783X1-0.1222X4+0.0682X5-1.2904X7+1.0814X8-0.1144X9+0.0532X10+0.0284X13,their multiple correlation coefficient R=0.9577, had a significant level at P<0.01, variance of the sugar content of corn stalk (91.72%) is determined by the 8 characteristics.(4) The result of simple correlation analysis showed that stalk sugar content was not significantly negative correlation with grain weight per plant, but the result of partial correlation analysis revealed that stalk sugar content had a significant positive correlation with grain weight per plant at P<0.01. Increasing stalk sugar content might be favorable for improvement of grain weight per plant in corn(5) The plant height gave the greatest negative direct effect on stalk sugar content among all characteristics, whose direct path coefficient was up to -1.2480. Days from sowing to silking and the ear leaf area had predominant positive direct effect on stalk sugar content,whose direct path coefficients were 1.0976 and 0.9858, respectively. Appropriately reducing plant height, extending silking date and increasing ear leaf area might be useful in improvement of stalk sugar content.