| The different filial generations of cross between curvature panicle and erect panicle rice varieties were used as the experimental materials and were grown in in south China, Guangdong province; in southwest China, Sichuan province; in northeast China, Liaoning and in middle and lowed Reaches of Yangtze River, Shanghai. It was designed to compare the differences in plant types and rice yields, to reveal the effect of ecological environments on plant type traits, yields, subspecies characteristics and panicle traits of different filial generations of cross between curvature panicle and erect panicle rice varieties; the differences of different plant types were 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-yeilding rice in different regions. The main results are as follow:(1) The ecological conditions had a significant effect on plant type traits and yield traits. From Sichuan to Liaoning, the plant high and panicle curvature had increased significantly, the panicle length, flag leaf length, flag leaf width and Leaf angle decreased. Number of panicles,1000-grains weight, seed setting rate and yields in Liaoning were significantly higher than Sichuan, grains per panicle in Sichuan was significantly greater than the Liaoning. In the four patterns of plant type yield components in the comparison, the no. of panicles1000-grains weight, seed setting rate and yields had demonstrated Cw> Cz> Dw> Dz, the number of panicles and grains per panicle of Dz minimum, Cz and Cw higher. The relationship between flag leaf length and yield traits was not to reached significant, the flag leaf weight and no. of panicles achieved significant level under different environment. in Liaoning, the seed setting rates indicated a significant negative correlation with flag leaf weight. The panicle curvature showed a significantly positive correlation with the Seed setting rate and yield traits in Sichuan, but it’s not significant correlation with the most of yield traits in Liaoning.(2) The subspecies characters in F2generations were continuously varied in different environments. Two populations were generally normal distribution in Sichuan, but obviously indica-like in Liaoning. The effects of environment on six traits of Cheng’s index were incompletely consistent. The ecological conditions had a significant effect on plant type traits. The plant height and panicle curvature increased significantly, but the panicle length, flag leaf length, flag leaf width and leaf angle decreased in Sichuan. Plant height in different subspecies had no obvious regularity in different regions. Flag leaf length was longer in indica(H) than in other types, but flag leaf angle had no significant difference in different subspecies and environments. Flag leaf width was changed with the cross combinations. Generally, panicle length reduced, but panicle curvature increased progressively from indica(H) to japonica(K) type. The subspecies characteristics were certainly related with plant type traits, but the correlation between them was not consistent in different cross combinations and environments.(3) the grain yield showed a downward trend from high latitude to low latitude. There existed a large difference in plant type traits across regions. The plant high was significantly higher at Sichuan and Liaoning than that at Shanghai and Guangdong. The panicle length in the four regions showed trend of Shanghai>Sichuan>Guangdong>Liaoning. There was a significant difference in flag leaf length, ie. Shanghai>Guangdong>Sichuan>Liaoning. The flag leaf width was Sichuan>Liaoning>Shanghai>Guangdong. The flag leaf angle in Liaoning and Guangdong was larger than that in Shanghai and Sichuan. Panicle curvature was significantly influenced by genetic factors.(The difference in panicle curvature was due to the different populations in different environment). Hereditary factor played a major role in the selection of panicle type. Cw with characteristics of super hybrid plant type model showed significant vigor in Guangdong, Sichuan and Shanghai. However, erect panicle plant type (Dz) was more adaptable to the environmental conditions in Liaoning, where rice grows longer with relatively fine weather condition and with more spike numbers. There existed a closely correlation between the plant type traits and yield components. Yet, the correlative direction and degree were not completely consistent due to different populations in different ecological environments. In the ideotype breeding practice, the criteria should be regionalized based on local climatic and cultivation conditions. Such breeding should not only have the traits of "space", but also have specific geoecotype.(4) The brown rice rate, milled rice rate, head rice rate, amylase content were significantly higher at Liaoning than that at Sichuan. The Chalky grains and Chalkiness were significantly lower at Liaoning than that at Sichuan. The difference in protein content was due to the different populations in different environment and was significantly influenced by genetic factors. In the four patterns of plant type, the milled rice rate and head rice rate of erect panicle plant type (Dz) showed significant vigor in Sichuan, the brown rice rate, milled rice rate and head rice rate at Liaoning had no obvious differences in different plant type model. The Chalky grains, Chalkiness, protent content and amylase content showed no obvious difference among different plant type model. The relationship between grain quality and plant type traits was not only significantly influenced by ecological environments, but by hereditary factor. Subspecies characterictics in Sichuan has no significantly selection pressure on grain quality, the effect of morphological classification on grain quality at Sichuan had not significant. There had a certain effect of Subspecies characterictics on grain quality at Liaoning. With the increasement of japonica ingredient, brown rice rate, milled rice rate, head rice rate and score showed increased trend, especially the head rice rate affected by subspecies characteristics was most significantly. The appearance quality at Liaoning showed an improved trend with the increasement of japonica ingredient.(5) Panicle traits had changed significantly under different ecological environments. Yet, the varied direction and degree were not completely consistent. The number of primary branch was significantly higher at Liaoning than that at other regions. The number of Secondary branch at Guangdong showed lowest. The Grains number per panicle, Seed setting rate of primary branch and spikelet density in the four regions showed trend of Liaoning>Sichuan>Guangdong and Shanghai. Thousand grains weight was highest at Sichuan and lowest at Guangdong. The seed setting rate showed trend of Liaoning>Sichuan> Guangdong> Shanghai and the panicle weigth showed Sichuan>Liaoning> Shanghai> Guangdong. The ecological environment was one of the most important causes of the difference of panicle traits under different regions. There existed a closely correlation between the plant type traits and panicle traits. Yet, the correlative direction and degree were not completely consistent due to different populations in different ecological environments. In the Liaoning breeding practice, the partial indica pedigree should be appropriately introduced, thus the branch number, seed number and seed setting rate, grains weight could reasonably integratation. With the increasement of japonica ingredient, seed setting rate showed increased trend at Sichan and Shanghai, yet, grains weight and panicle weight showed trend of increasement at Guangdong. On the premise of guarantee of grains number per panicle, with the join of japonica ingredient could improve the defect of inferior seed setting rate at Sichuan and Shanghai, while could raise the panicle weight at Guangdong. |
PDF Full Text Request