Studies On The Regulation Of S-3307 On Rice Quality

The effects of S-3307 (Uniconazole) by soaking and spraying at booting stage with different concentrations (0, 10, 20,40 and 80 mg/kg) on the characteristics of flag leaves, grain growth, accumulation of carbon and nitrogen in grain, rice quality and yield were studied with hybrid rice combination Shanyou63. The main results were shown as follows:1. The Chlorophyll contents in the leaves and area of green flag leaves on main stem during leaf senescence were increased after S-3307 treatment with suitable concentration, that is, S-3307 has the function of postponing leaf senescence and lengthening the photosynthetic period. However, spraying S-3307 with higher concentration (80mg/kg) at booting stage promoted leaf senescence, and made green leaf area lower than the control in later period.2. S-3307 treatment increased total soluble sugar and protein content in flag leaf at earlier period of grain filling, but the total soluble sugar and protein content in flag leaf was no more, even lower than that of control in mature period, thus accelerated the accumulation of carbon and nitrogen in leaf and export to grain.3. Application of S-3307 had different effects on superior and inferior grain. The growth of superior grain was inhibited, while that of inferior grain was promoted, so, the seed weight of inferior grain was increased in some degree. The grain-filling processes of superior and inferior grain were simulated with Richards equations and Logistic equations, respectively and some grain-filling parameters were derived from each equation. In theses equation parameters, the ultimate grain weight was decreased and the time reaching to the maximum filling rate was prolonged in superior grain after S-3307 treatment, the filling duration of inferior grain was lengthened, and the average filling rate and ultimate grain weight of that was increased, however.4. S-3307 treatment increased soluble sugar content of superior grain at earlier stage and that of inferior in earlier and middle period. At later stage, the soluble sugar content in all grain under S-3307 treatment was lower than that of control. It was the matter basis of starch production and accumulation in grain. S-3307 treatment inhibited the accumulation of superior grain in earlier and middle period, but stimulating it at later stage, so the final amount of starch was not significantly higher or lower than that of control. As inferiorgrain, S-3307 treatment accelerated the accumulation of starch in it, and the starch content was higher than that in control, that is the effect of S-3307 on inferior grain was greater than superior grain5. S-3307 treatment increased GS activities in grain and non-protein nitrogen content at earlier stage of grain development, and promoted non-protein nitrogen transforming into protein nitrogen, thus both protein percentage and amount of protein in a grain were enhanced.6. S-3307 treatment significantly increased ratio of head milled rice and crude protein content of rice grain, and significantly decreased gelatinization temperature. On the contrary, the other qualities was almost not influenced by S-3307.7. S-3307 can increase rice yield through significantly increasing the grain number per panicle. At the same time, if the time of using S-3307 was different, the best concentration was different as well.