Studies On Summer Maize Kernel Setting Capacity At Different Microelement Fertilizer Treatments

The morphology and physiological characteristics of kemel development, kernel setting capacity at different anthesis-silking interval (ASI) and the effect of microelement fertilizers(zinc, manganese, boron,) on summer maize growth and development kernel setting rate were conducted using nongda108 as experimental material. The results would help to provide key factor affecting summer maize growth and development, and effects on kernel setting capacity by different microelement fertilizers. The results were showed as follows:1. The most rapid dry matter accumulation was appeared at 12 to 28 day after anthesis (DAA) during the kemel development. And this period was also a key period for dry matter accumulation and yield formation. During the kernel setting period they all showed a fast increasing trend on kernel ovary size, fresh weight, dry weight and volume. And there was a significant positive correlation between kemel weight and volume. Changes of kernel development at different ear positions were also checked and it showed that middle kernels were better than upper kemels on length of ovary, fresh and dry weight, and volume. That also means the kernel sink stress and sink activity of middle kernels were better than the upper ones. That maybe a reason of upper kemels had a high aborted rate.2. The contents of soluble sugar, protein and starch of the kernel and cob were compared. The result indicated that there were a similar trend between kernel and cob with in 12 day after anthesis (DAA). After 12 DAA the starch content increased rapidly in the kernel, however, it was relatively decreased in the cob. The content of soluble sugar kept high in the kernel, but decreased rapidly in the cob. During the whole kernel development, the protein content of the kernel was higher than that of the cob. It was estimated that the soluble sugar of cob was transported to kernel and converted to starch or protein after the 12 DAA.3. The content of soluble sugar, protein and starch of the kernel and cob in different parts of the ear had different changing trends, but 12 DAA is a key day of the physiology characteristics, all of the three indexes had changed after 12DAA. Enhancing management before the 12 DAA could improve kernel development, decrease abortion and raise seed-set rate. 4. The experiment changed the anthesis-silking interval (ASI) by bagging the ears and removing bags during silking period. The results showed that the changes of ear length and ear diameter were not significant with widen space of ASI. ear length kept about 17 to 19 cm and ear diameter reduced slightly, but it showed strong effect to the length of bare tip, number of rows per ear, grains per row and grains per ear. The yield decreased significantly with widen space of ASI and had slightly influence with narrow space of ASI. On the other hand, ensure the plant characteristics and field environment could improve kernel setting ability at flowering and early filling period.5. The effect of leaf applying different microelement fertilizer (Zinc, Manganese, Boron) on the growth and development and kemel setting rate of summer maize was conducted. The result showed that plant characteristics and developing situation between microelement fertilizer treatments and control plot were basically the same.The effect of applying once (at about 5 leaf stage) or twice (about 5 and 10 leaf stage) of microelement fertilizers on maize nearly the same. Leaf area of treatment was a little better than control plot, but it differ with different microelement fertilizer treatments. The speed of silking of different microelement fertilizer treatments plants was higher than control plots though the treatment had little effect on ASI. The effects on silk elongation in a decreaseing order was: Zinc, Manganese, and Boron. Fast and centralize silking were beneficial to receive pollen, decrease kernel abortion.6. The studied also showed that microelement fertilizer had some effects on dry matter distribution. The changes of ear length, ear diameter and number of rows per ear were not significant. But the length of bare tip cut down and the number of grains per ear were increased. All the treatments increased the yield. The mean kernel setting rate of different microelement fertilizer treatment was 77%, whereas it was 4% higher than control plot.