Synchronism Of The Development Of Ear Sinks And It's Regulatory Mechanism In Maize

Gao Guang Xiao 1 which was Semi-prolific varieties was used to study the development of ears and the process of spike differentiation, the synchronism of the development of ears. The combination of decaption and pollination was adopted to investigate the physiological changes of material metabolism, enzyme activities, endogenous hormone. The main results showed as follows:1. It was shown from the development of ears and the changes of ear length and ear fresh weight that the development process between apical and subapical ears was coincide; however, compared with the other ears, the difference was large. The length and fresh weight of ears were increase slowly during the leaf number was from 15 to 17; however, the length and fresh weight of ears changed greatly when the leaf number was 18. Therefore, the suitable stage of regulating the length and fresh weight among ears was before leaf number 15 (leaf number index 75%), in which upper first and second ear was sex organs differentiation.2. The development of more ears was realized by physical and chemical regulation. The decaption raised the ratio of potential two-ears, and pollination increased the ratio of real two-ears.3. Measurement on the nutrient materials among different ear sinks indicated that the ratio of sugar to starch increased after decaption; however, the ratio of sucrose to starch decreased, which was advantage to the development of second ear. The difference between apical and subapical ear was reduced, the development of them was coincident. The content of totalsugar in second ear increased with pollination and decaption. It was perhaps due to the earlier pollination and development of the second ear, the higher activities of sinks. The partition of assimilate was changed, which showed the allocation of assimilate among different ear sinks and the distribution of carbohydrate between translocation sugar and storage sugar. It was concerned from the ratio among sucrosen sugar and starch that the ratio of sucrose to starch can partly reflect the capacity of accumulating assimilate in grain. The accumulation of transient sugar was advantageous to reduce the abortion of ears.4. Comparison of enzymes activities between different sinks showed that the activities of SPS ^ SS and SAI in first ear was higher that those of second ear in control plants. Treatment increase the activity of enzyme in second ear and reduced the difference between apical and subapical ear. the increase of ADP-glucose pyrophosphorylase was advantageous to the synthesis of starch. Sucrose Synthase played more important role in the cleavage of sucrose.5. Endogenous hormone was measured between different sinks, the results showed that the content of Z reached peak after 5 DAP, the first ear had a higher level of Z than that of second ear in control. Treatment reduced the different between two ears. After 15 DAP, the IAA ratio of first ear to second ear was 3.19 in control; the IAA ratio of first ear to second ear decreased after decaption.Based on these results, a comprehensive model was established on the mechanism of the synchronism of ear development.