| High-yielding of rice plays a great significant role for food security and social stability. The strategy of generating the ideotype and the strong heterosis through inter-subspecific hybridization, then pyramiding the elite traits and genes by composite -crossing to breed the super -rice varieties with both ideotype and strong hybrid vigor would benefit super-high-yield. A series of RILs derived from the cross between an erect-panicle japonica variety’Shennong265’(SN265) and a curved-panicle indica variety’Luhui99’(R99) provide the ideal experimental material to evaluate the characterization of the relationship between vascular bundles features and indica-allelic frequency and analyze the different effects of DEP1 on vascular bundle-and panicle related traits under indica and japonica genetic backgrounds; The different filial generations of cross between curvature panicle’Wanlun 422’(WL422) and erect panicle’Liaojing 5’(LG5) rice varieties were used as experimental materials and were grown in in Shenyang China and Kyoto Japan. It was designed to compare the differences in panicle types, yield components, grain filling traits, canopy structure and light distribution in order to reveal the effect of ecological environments on the interaction among them, which was analyzed and to identify the correlation in different ecological environments. The purpose of this study was to provide theoretical basis in identifying the best plant type mode of super high-yielding rice in different regions. The main results are as follow:1. The quality and yield of rice are influenced by vascular bundles and highly significant differences about size and number of vascular bundles can be found among rice subspecies. In this study, we divided a series of recombinant inbred lines, which were derived from a cross between the indica variety’Luhui 99’and the japonica variety’Shennong 265’into pre-indica, intermediate and pre-japonica groups using subspecies-specific markers. We completed an in-depth analysis of vascular bundles characteristics at different panicle positions. The results showed that the number of large vascular bundles (LVBs) and the ratio of the number of LVBs to the number of primary branches (V/R ratio) of the three groups was ranked as pre-indica>intermediate>pre-japonica. However, a large variation in the number of LVBs and V/R ratio was observed inside each group. Increases in the LVBs and the V/R ratio did not result in increased numbers of primary branches, but led to an increase in the number of secondary branches. With the increase in the frequency of indica-allelic markers, the differences in the grain setting rate and 1000-grain weight among the upper, middle and lower panicle sections became significant. Thus, we concluded that crosses between subspecies, followed by selection of the vascular bundle related traits and indica pedigree, can optimize the number of LVBs and the frequency of indica alleles. The simultaneous increase in both LVB and primary branch numbers, which might lead to greater rice yields, and may be a goal for breeders and scientists.2. The aim of this study was to determine the effects of DEP1 on yield components and vascular bundle-related traits under indica and japonica genetic backgrounds. We analyzed a series of recombinant inbred lines, which were derived from a cross between the japonica variety SN265 with an erect panicle and the indica variety R99 with a curved panicle. The results showed that effects of the DEP1/depl allele were much stronger than the effects of the indica/japonica genetic background on vascular bundle-related traits and yield components. As the frequency of indica alleles increased, the grain yield per plant and the harvest index significantly increased in lines with the depl allele. Among the indica-type lines, those with the depl allele showed superior values for almost all of the vascular bundle-related traits and yield components. Our results provide new insights into the use of a high yield-related gene derived from japonica in the indica genetic background.3. The yield of Liaojing5 and erect panicle lines which derived from cross between curvature panicle’Wanlun 422’(WL422) and erect panicle’Liaojing 5’(LG5) rice varieties in Shenyang was significantly higher than that in Kyoto. With the increase of nitrogen input, the yield of filial generations from the cross improved. It could be detected the potential yield in curved type though the difference was not significant as the increasing nitrogen. The harvest index of erect panicle was examined the opposite tendency which was increased dramatically compared with LG5.The difference couldn’t be found caused by less biomass in erect panicle. In Shenyang, erect panicle was suggested more suitable to grow because of larger biomass and higher HI. The significant difference between two types of panicle among the grain setting rate, the ratio of length to width in grain with primary, secondary rachis branch were not observed.4. The plant traits of curved panicle could be summed up as follows:the higher canopy height, narrower flag leaf, shorter 1st internode and first sheath. The major conclusions of erect panicle were that the angles of flag,2nd,3rd 4th leaves were larger and the extinction coefficient from transplanting to maturity was consistently lower. The leaf area index of erect panicle was larger from transplanting to 50 days after transplanting, then that of curved panicle turned into larger. At heading stage, the extinction coefficient of erect panicle in every 10 cm with upper part was smaller caused by larger LAI and larger leaf angle. However that of two types of panicles was similar. In 15 days, after heading stage, LAI of curved panicle in every 10 cm was larger and extinction coefficient was smaller. As for the dry matter distribution, the panicle was more concentrated in first 30 cm with erect panicle while 20-40cm with curved panicle. The crop growth rate and net assimilation rate were lower in erect panicle at heading stage. As the grain began to accumulate, the tendency changed into opposite in 15 days after heading stage.5. The grain weights inside each part of primary and secondary branches with erect panicle were larger than that with curved panicle. Duration from beginning to stability of grain filling on primary rachis branch with two types indicted that upper and middle parts were shorter than lower. What’s more, durations were longer in each part on secondary rachis branch compared with primary branch. The duration of grains in lower part with erect panicle would last till the end of grain filling especially. |
PDF Full Text Request