Effects Of Different Sowing Date And Planting Density On Yield Formation And Quality Of Two Medium Japonica Rice Varieties In Huaibei

The experiment was carried out during 2006-2007 at Pingming town of Donghai country in Jiangsu province. The soil type is the waist-black-loess, the soil fertility was medium, the previous stubble was wheat middle-maturity medium japonica rice xudao3 and early-maturity medium japonica rice Liaoyou1052 were taken as materials, the effect of different sowing date and planting denstity on yield formation and rice quality of two rice cultivars were studied. The main results were as follows:1. The whole growth period of two varieties become short when the sowing date is postponed. The length of the whole growth period was mainly affected by sowing date. Every stage of Liaoyou1052 came earlier than that of Xudao3. Liaoyou1052 matured 12 to 17 days earlier than Xudao3. The whole growth period of two varieties were influenced by planting density slightly. Each stage of the treatments with higher planting density postponed 1 to 2 days. The difference of the whole growth period length was mostly decided by the difference of days before heading period.2.The yield range of Xudao3 and Liaoyou1052 were 595.5～736.4kg/667m2 and 514.4～616.1kg/667m2 respectively. The treatment A2B2 and A2B3 achieved the highest yield both in Xudao3, significant higher than the other treatments. The sequence of the yield of Xudao3 from high to low in different sowing date was 5/15 > 5/5 > 5/25 > 6/4 > 6/14. The treatment A5B3 of Liaoyou1052 got the highest yield. The sequence of the yield of Liaoyou1052 from high to low in different sowing date was 6/14 > 6/4 > 5/25 > 5/15 > 5/5. The larger the planting density was, the higher the yield both Xudao3 and Liaoyou1052 were.The treatments of Xudao3 which achieved the yield exceeded 700kg/667m2 had 20.0×104～21.5×104 panicles per 667m2, 170～176 grains per panicle, 25～26 gram per 1000 grain and 82% seed-setting rate.The sowing date 5/15 treatment was the best to achieve the highest yield. The treatments of Liaoyou1052 which achieved the yield exceeded 600kg/667m2 had 17.0×104 panicles per 667m2, 179 grains per panicle or above, 23.5～24 gram per 1000 grain and 88～89% seed-setting rate. Sowing seeds in 6/14 or several days later was the best sowing date to achieve high yield. The degree of variation of yield components influenced by sowing date and planting density showed that Xudao3 can get higher yield by increasing panicles and grains per panicle, while Liaoyou1052 by getting more panicles.3. High yield group had obvious superiority in biomass production accumulation or production and accumulation of dry matter in each growth period. The treatment A2B3 of Xudao3 had highest dry matter accumulation and nitrogen utilization efficiency in mature period. The treatment A5B3 of Liaoyou1052 had largest dry matter accumulation and nitrogen utilization efficiency in mature period. The treatment of lower yield had less biomass production accumulation and nitrogen utilization efficiency.4. The results showed that the rice quality was highly affected by sowing date and planting density, especially the chalkiness as well as chalkiness ratio. The amylose content, protein and gel consistency followed. The effect of sowing date and planting density was small on head milled rice rate, brown rice rate and milled rice rate. The processing quality of Xudao3 was first decreased and then increased as the postponing of sowing date. As the increaseing of planting density, the processing quality first increased and then decreased. Processing quality of Liaoyou1052 tended to increase with the postponing of sowing date ,and decrease with planting density increasing. The apparent quality of Xudao3 first increased and then decreased with the postponing of sowing date or increasing of planting density. The apparent quality of Liaoyou1052 increased with the postponing of sowing date and declined with planting density increasing. Protein content of Xudao3, first decreased and then increased after the sowing date postponing. The variation affected by planting density was contrary to this. Protein content of Liaoyou1052 first increased and then decreased with the postponing of sowing date, increased with the increasing of planting density. The variation of amylose content and gel consistency in two varieties affected by sowing date and planting density were contrary to that of protein content.Different sowing date and planting density affect characters of RVA greatly. As the delaying of the sowing date, peak viscosity, hot plasm viscosity, breakdown and final viscosity of Xudao3 first increased and then decreased,while the setback raised. The breakdown first decreased and then increased as the enlarging of planting density, the setback in reverse. The peak time and pasting temperature of Xudao3 first increased and then decreased as the delaying of the sowing date, no obvious regular changes as the increasing of plant density. As delaying of sowing date, peak viscosity of Liaoyou1052 decreased, hot plasm viscosity and break down raised first and dropped afterward. final viscosity and setback increased. As plant density increasing, the peak viscosity and breakdown decreased, hot plasm viscosity tended to be upward first and then downward, while the final viscosity and setback on the contray. The peak time showed the trend of rose first and declined next. High planting density treatments had the higher peak time. Pasting temperature falled followed the delaying of sowing date.The changes were not in evidence as the increasing of plant density.According to safety, high yield and good quality, Xudao3 and Liaoyou1052 should be sowed from May 10 to May 20 and from June 10 to June 20 respectively in Huaibei.