| Ratoon rice is a light and simple cultivation technology with saving labour and cost, increasing yield and benefit, which will play an important role for raising food yield and farmer's income. Several hybrid combinations with high ratooning ability newly bred in China were planted at Youxi county of Fujian province by the field experiments and demonstrations in 1998-2003. High-yielding demonstration fields of ratoon rice were established and the characteristics of climatic condition, sink-source structure, root system morphology and function, and nitrogen (N) absorption and accumulation were studied for high-yielding cultivation of ratoon rice. In addition, a F2 population and a corresponding simple sequence repeats (SSR) molecular marker linkage map were established and constructed from a cross between two indica cultivars, Minghui86 and Jiafuzhan. The relationships among main traits of ratoon rice were analyzed and QTLs of controlling main traits of ratoon rice were mapped and analyzed by Free and Additive models of interval mapping. The results were summarized as follows:1 The demonstration field areas of high-yielding ratoon rice were added up to 1364 hm2 at Youxi county of Fujian province in 1998-2003, the average yield of which was 11158 kg-hm"2 in the first crop and 6560 kg-hm-2 in the ratoon crop, respectively. Double-cropping yield amounted to 17718 kg-hm-2. Among them, the average yield of 6.7hm2 key demonstration fields in 2000-2003 reached 12533 kg-hm-2 in the first crop and 7434 kg-hm-2 in the ratoon crop, respectively. And some high-yielding fields which yielded over 13t-hm-2 in the first crop and 8t-hm-2 in the ratoon crop of ratoon rice were observed, respectively, and the highest yield of the ratoon crop reached to 8742 kg-hm-2.2.The grain yield and light energy utilization efficiency of ratoon rice greatly increased with an earlier sowing date (in the first 10 days of March) in that it extended the vegetable growth period of the first crop, raised accumulated temperature, sun light irradiation time and total solar radiation energy in the first and ratoon crop, in turn resulted in significantly enhanced photosynthetic efficiency and dry matter accumulation. In addition, with the earlier sowing date, the first crop avoided the damage of Orseolia oryzae (Wood et Mason) and the ratoon crop escaped from the autumn coldness.3.The feature of high-yielding ratoon rice was a larger sink size. The contribution rate of sink size to grain yield was larger than that of seed-setting percentage. The same tendency was found in the contribution rate of total spikelets per m2 to sink size, showing larger than that of grain weight. It was also indicated that the contribution rates to total spikelets per m2 were: spikelets per panicle larger than panicles per m2 in the first crop and panicles per m2 larger than spikelets per panicle in the ratoon crop. Therefore, the high-yielding ratoon rice need establish large sink size by developing much more spikelets based on stable panicle in the first crop and by cultivating the panicles in the ratoon crop more than one time in the first crop.4. The higher yield of ratoon rice also need accumulate larger biomass. The contribution rate of total dry matter accumulation to grain yield was larger than that of harvest index. The contribution rate of net dry matter accumulation at mid-late stages to total dry matter accumulation was also larger. It was also indicated that the contribution rate of crop growth rate (CGR) to net dry matter accumulation of different stages was larger than that of growth days, and the contribution rate of leaf area to crop growth rate was larger than that of net assimilation rate (NAR). Therefore, the high-yielding ratoon rice need develop larger leaf area at mid-late stage and must possess erect leaves, higher CGR and dry matter accumulation at mid-late stage in the first crop. And the high-yielding ratoon crop need produce more ratooning tiller, enlarge leaf areas of population and greatly accumulate dry matter.5. The grain yield of ratoon...
|
PDF Full Text Request