| High yield is the eternal theme of rice breeding. The improvement of production mainly comes from the contribution of grain number per panicle; big ear is one of the most important ways of realizing super-high-yield rice. The morphological characteristics, physiological characteristics and yield components were studied by using large panicle varieties R1126and its combination as research material in this paper. The main results were as follows:1) Large panicle varieties R1126and its combination have high yield potential; the grain yield of those was10.1%to26.8%higher than that of Shanyou63. Increasing total grains number per panicle is the direct cause of high yield. The combinations of R1126have high stability coefficient (HSCi) which were8.4to22.1%higher than that of Shanyou63. It show that the performance of high yield and stable yield were better. Moreover, the production of R1126and its combinations was positively correlated or significant positive with grain number. It has "compensation effect" between spike grain number and effective panicle number. In order to realize the super-high-yield, rice varieties should coordinate the relationship between the yield components.2) Large panicle rice variety R1126and its combinations have steady tiller performance, the tillering rate were6.9to12.5%higher than that of Shanyou63. Plant height is proper which were about120cm with stem stout and long peduncle; Compared with shanyou63, the LAI were slightly lower, but the efficient rate of leaf area and the grain leaf ratio were slightly higher, as well as the LAI fall slower. The top3leaves were longer, wider, thickr, and straightter, the leaves configuration on the stem is reasonable. It has more primary and secondary branch number and more branch grain number. Seed setting rate was stable.3) The root of large panicle rice variety R1126and its combination was longer, stouter and deeper. Single stem has more number roots, the root dry weight was heavier, and the attenuation was slower. Root total absorption area and active absorption area is bigger, root activity was stronger. There have bigger ratio of No. of filled grains to root exudates, ratio grain weight to root exudates and root-shoot ratio after heading. The relationship between underground and aboveground was harmonious that can guarantee the absorption of nutrients and moisture,at the same time anti-aging which of the above was favorable to improving the capacity of plant photosynthetic efficiency and transporting photosynthetic matter to grain.4) Compared with Shanyou63, large panicle rice variety R1126and its combinations have higher net photosynthetic rate, longer functional leaf area duration and larger photochemical efficiency. The adaptability to environmental was wider. At the same time, the leaf senescence was more slowly because of higher chlorophyll content, SOD activity and rubisco activity which were in favor of the accumulation of photosynthetic products. It was very significant positive correlation between Yield with photosynthetic potential, efficient rate of leaf area and the Pn, but it is not obvious associated with LAI. The Photosynthetic source of R1126and its combinations was sufficient.5) The biomass production of supper large panicle rice was bigger and its harvest index was0.51to0.56. Both are having closed relation to yield. Dry matter accumulation of single stem was obvious large. However, dry matter accumulation of group is less than CK before jointing and considerable to CK in the period from jointing to heading, and significantly higher than CK after heading. It presented the features which is small at the early period, steady in the medium and high at the late growth stage. Dry matter allocated to various organs was rational and the efficiency of dry matter transport to ear was high. Grain yield was significantly negatively correlated with the contribution rate of storage material before heading and significantly positively correlated with the contribution rate of accumulated dry material after heading. Increasing dry matter production after heading and improveing the translocation efficiency of stem and sheath can help to improve the yield of supper large panicle rice.6) The grouting of large panicle rice variety R1126and its combination start fast and the grain weight increase quickly. It can reach the maximum grouting rate earlier. Grouting differences between strong and weak grains were smaller. The grouting filling rate and its contribution rate wre higher at the middle grouting stage. It still can keep high rate of grouting at the late grouting stage. The grain library activity and average grain library activity were high at the early and middle stage that is good for improving grain weight and grain fulling. 7) The panicle neck internode organizations including the vascular bundle number, vascular bundle area, area of phloem, cross sectional area and the stem wall area of large panicle rice variety R1126and itscombinations were significantly higher than that of shanyou63. The same as to each part of the panicle branch organizations including the vascular bundle number and vascular bundle and area. The load of phloem didn’t produce "disorder" structure and the grain filling weren’t affected too much. The lower branch vascular bundle, mostly growthed weak grains, development was not very well and its load was big that may be the important reason of poor grain filling. The neck phloem’s total area load of the number of spikelets, the solid grain weight and the total storage capacity were significant or extremely significant negative with the biggest grouting rate (GRmax) and the average filling rate (GRmea) of strong and weak grains, negatively correlated with grain fill rate, and significant positive correlated with the active grain filling period (D), the valid grain filling time (T99) and the maximum grouting speed time (Tmax). Conducting tissue activity was significantly or extremely significantly positive correlated with GRmax and GRmea, positively correlated with the grain filling rate, and significant or extremely significant positive correlated with D, T99and Tmax.The conducting tissue of the panicle neck and the panicle branch was closely related to the grain filling and the grain yield. To improve the character of the conducting tissue of the panicle neck and the panicle branch can be in favor of the grain filling character and so to increase production. |
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