Study On The Effects Of Hybrid Rice‘s Photosynthetic Product And Sieve Tube Structure On The Conversion Rate Of Dry Matter Between Subspecies

The heterosis utilization of Hybrid rice between subspecies is an important way to realize rice super high yield breeding programs, but the low matter conversion rate of the hybrid becomes the bottleneck to get high yield. To further explore the reasons for the low conversion rate of dry matter and explore the coordination mechanism of biological yield’s potential and grain yield’s potential, the study whose materials are a male parent(R292), three female parent(Y58S, Peiai 64 S and 83S), and three hybridized combinations between subspecies(Y58S/292,64S/292, 83S/292) and contrast(Yueyou 9113) were selected for this studied to identify the correlation of the agronomic characters among the female parents and their F1 hybrids, and the correlation of conversion rate and yield of dry matter between structure of sieve tube. The results showed that:(1)During all the periods the soluble sugar and starch content of all the selected material showed a trend of dynamic change and there were significant and extremely significant difference. In the female parent the highest soluble sugar content is 83 S with a significant content in the four periods and it’s extremely higher than Peiai 64 S and Y58 S. Among hybridized combinations between subspecies relatively high content ones are 83S/292. There is significantly positive correlation in the characters among the female parents and their F1 hybrids. Contrasted with Yueyou 9113, the soluble sugar content in the stage of yellow ripeness is relatively low which explained that it’s a huge transformation to photosynthetic products of the panicle. From the point of all the periods, in addition to outside the 83S/292 in the yellow ripening period is on the decline, the content was low in the booting stage and it rised quickly in the heading stage and full heading stage while it went down in the yellow ripeness stage. From the point of different parts, the highest content of soluble sugar is only the stem part followed by peduncle and it’s relatively low in the stem-sheath and boot leaf parts. Like 83S/292 for instance, the total content of stem, stem-sheath, boot leaf andpeduncle in the booting stage respectively is 36.81%, 14.28%, 22.58% and 26.33%. The starch content in the four parts in different stages respectively is a total of 25.85%, 23.82%,18.97% and 22.21% which showed that it’s not significant difference in the starch content in different parts.(2) The database of hybridized combination among three subspecies is significantly greater than the varieties of hybrid rice Yueyou 9113, the 64S/292’s database is the highest which reached 226 grains per panicle. It’s a big advantage to achieve high yield for hybridized rice between subspecies that there is a relatively huge database. But the output rate,conversion rate, seed setting rate of Peiai 64S/292 and Y58S/292’s dry matter were significantly lower than contrasted Yueyou 9113 and 83S/292 is significantly lower than that of Yueyou 9113. Conversion rate is the important limitation factors of hybridized rice between subspecies though there’s relatively high biological yield’s potential.(3) Three subspecies’ s hybridized combination Y58S/292, 83S/292, the 64S/29 its big vascular bundle’s number(small vascular bundle’s number) respectively is 21.2(21)、20.9(21)、21.7(21) which are both higher than that contrasted. A single bundle’s sieve tube number among the three hybridized combinations between subspecies respectively is 23, 22,24 while the contrast Yueyou 9113 is 28 and they are respectively lower by 17.9%、21.4%、14.3% than the contrast one. A single bundle’s area is respectively smaller by 12.8%, 3.4%and 2.2% than the contrast one.(4)Output rate and conversion rate and a single bundle screen number were significantly positive correlations and the correlation coeffients were 0.979 and 0.991;Conversion rate, seed setting and single bundle screen number were significantly positive correlations and the correlation coefficients were 0.959 and 0.954.Therefore, in the proposition of guaranteeing the rice yield advantage of biological yield and the large database and so on advantages between subspecies, to improve "flow" state of rice operation, especially to improve the sieve tube’s characters through gene and cultivation and so on areas’ measures, will be an important approach to the future development of hybrid rice between subspecies.