The Effects Of Different Forms Shading On The Quality Of Rice After Heading

In the experiment, low amylose content Japonica rice Naihuanghou, middle amylose content Japonica rice Fengjin, high amylose content Indica rice Xingfeng were used to study the influence of different intensity (set five different degree of light intensity: natural light intensity, shading rate which were 51%, 72%, 85%and 89% of the natural one respectively in the rate of shading) and different sunshine lengths (4 different sunshine lengths: natural sunshine length, 11h, 10h, 9h of sunshine everyday) on the productive properties and qualities of the rice and hybrid rice Gangyou26 and Japonica rice Ribenqing were employed to research on the effects of different lengths (5days, 10days, 15days respectively) on the qualities of rice. The result are as followed:1. The effects on the growth of the flag leaves: In different sunshine intensity, the lengths of leaves becomes longer than control, while the changes of the width are not distinct. With the reduction of the intensity, the average areas of the leaves are larger than control. The amount of Chlorophyll a and Chlorophyll b increases obviously accordingly. The longer the shading time is, the clearer the effects on the leaf length, width and the amount of chlorophyll are. Shortening the length of sunshine cannot affect the width of leaf but increase the amount of Chlorophyll a and Chlorophyll b.2. The effects on the grain filling: In the weak light, the ability of producing rice stuff decreases, and the filling rate is even lower than the control. And the filling rate reduces sharply with the reduction of the light intensity; correspondingly the time of filling needs is much longer than control. It prolongs about 15 days longer in the treatment of extreme weak light. Long-time shading treatment has more influence on grain filling than short time one. Shortening the sunshine time can decrease dry weight of the grain and postpone the summit time of filling.3. The effects on grain yield: With the reduction of light intensity, the actual amountof the ears of grain and the weight per one thousand grains drop noticeably; The yield has the same result. As for the treatment of the district shading lengths, the treatments of the earlier stage and long time shading case the decrease of the actual amount of the grain and unnoticeable change of the weight per one thousand; they decrease by a larger scope with the lengthening of shading time. In the process of shortening the daytime heavily, compared with the control, the yields of them decrease by 4.31% and7.01% respectively, while the treatment of shortening daytime slight is unnoticeable.4. The effects on amylose content: Weaking light intensity can reduce the amount of amylose content, strengthening shading extent and lengthening shading time, there is a distinct decrease. Shading in the earlier stage has more effects than that in the later stage. The influence brought in by longtime shading is more than that induced by short time shading. There exists a clear curve of change between the amount of amylose content in the rice and the days after shading. This kind of change can be simulated by square or cubic curve equation, and achieve the significant or quite significant level.5. The effects on the amount of the protein: Decreasing the light intensity increases the amount of protein of grain. Related analysis shows that there is a significant negative correlation between the amount of protein of grain correlates and the light intensity with the correlation coefficient as r=-0.98. But the correlation isn't distinct in different time of sunshine. The further dynamic analysis of the accumulation of the protein finds that the correlation between the amount of the protein and number of the days can be imitated by linear regressive equation, and the difference is noticeable.6. The influence on the quality of rice: In the force of long-term weak light, the comprehensive quality of rice becomes worse. Lengthening shading time and weakening light intensity, the rate of brown rice, milled rice, head rice drop significantly or at the extreme level; on the other hand, the rate of chalky rice and the extent of chalk-whiteness increase significantly; The amount of the amylose content and the glutinosity starch decreases, while the content of protein increases significantly. However, shortening the length of sunshine can reduce the rate of chalky rice and the extent of chalk-whiteness.