Study On The Characteristics Of Yield And Quality Formation And Techniques For High Quality And High Yield Cultivation Of Rice In Panxi Region

The Panxi Region, of Sichuan province, is a special rice cultivation region with a low latitude and a high altitude. It is situated in the intersection area of Sichuan Basin, YunGui plateau and QingZhang plateau. In this paper, twenty-seven field experiments with a total of 683 plots consisted of different sowing dates, variety comparison, source-sink regulation, fertilizer management, transplanting densities, water management, seedling and transplanting meathod experiment, etc. were conducted at a scope of altitudes from 539m to 1787m in eight counties of Panxi and its neighboring regions in 2002-2003. In the mean time, twenty reference rice samples from ten other rice producing counties in Panxi Region were analyzed. The characteristics of grain yield and quality formation in rice, especially the relationship between yield and its components, main rice quality properties and the altitude of planting sites, were comprehensively studied. The high quality, high yield and nuisance-free cultivation techniques of rice in Panxi Region were discussed. The main results were as follows:1. There was a close relationship beteen grain yield, yield components and the altitude of planting sites in rice in Panxi Region. Grain yield and its components of rice varied with the altitudes of planting sites where the main ecological factors such as temperature, light, etc. were different. The experimental results in this study showed that the number of effective panicles and spikelets per area were positively correlated to the altitude of planting sites, while the number of total grains and filled grains per panicle were negatively correlated to it. The relationship between the percentage of filled grains, grain yield and the altitude of planting sites fit to a quadratic function (except for the grain yield of Changmi 011 which was linearly correlated to the altitude of planting sites). The altitude with the highest percentage of filled grains was about 1000m, and that of the highest grain yield was in the range of 1250m to 1580m. The altitude with the highest grain yield varied with the cultivars of rice. The degree of reponse to the altitude of planting site by grain yield and its components, i.e. the sensitivity of grain yield and its components to the altitude, also varied with cultivars. The sensitivity of grain yield and its components of the Japonica varieties to the altitude were lower than that of Indica rice, while that of hybrid Indica rice was the largest.For high yield cultivation, the main yield components to be improved differed with cultivars and the altitude of planting site. The results of this study indicated that there were two main characteristics of yield formation of rice in the middle and the high altitude areas in Panxi Region, one is more effective panicles and more spikelets, another is lower percentage of filled grains. So the general strategy of high yield cultivation is to increase the percentage of filled grains on the basis of enough effective panicles. Concerning about different types of varietites, the main target of high yield cultivation of hybrid Indica rice is to increase the percentage of filled grains because it had larger ears and lower percentage of filled grains, while that of Japonica rice is to increase the number of effective panicles since it had smaller ears and higher percentage of filled grains, and for the cultivation of conventional Indica varities it is to get more effective panicles under lower yield condition and to increase the percentage of filled grains under higher yield condition. For different altitudes of planting sites, the goal of high yield cultivation for altitudes lower...