Group Growth Characteristics And Nitrogen Utilization Efficiency Of Rice Varieties With High Efficiency

Rice is an important food crop in our country.With the development of economy,rice production has changed from single pursuit of yield to high quality and high yield,and meanwhile,rice mechanized planting has been widely promoted as a modern cultivation mode with high efficiency,high yield and stable yield.The efficient planting methods such as machine transplanting have brought about new changes in the requirements of rice varieties.High efficiency and high quality production has become an inevitable requirements for mechanized large-scale production of adaptable varieties.Due to the lack of research on the characteristics and mechanism of rice varieties synergized by high-efficiency,high-yield and high-quality production,it has become a restrictive factor for modern rice production and variety improvement.In this study,yield formation,group development,material production and nitrogen fertilizer utilization of different types of hybrid rice and conventional japonica rice are analyzed.Group growth characteristics of high-yield and high-yield varieties and their responses to cultivation measures are also analyzed.The research findings can provide the necessary theoretical basis for the construction of rice high-efficiency and high-yield technology system and the breeding of rice varieties.The main findings are as follows:1.Generally speaking,rice varieties are defined as three types:high-efficiency and high-yield,low-efficiency and high-yield,and ordinary varieties according to yield and production efficiency(daily production).Compared with ordinary rice varieties,the yield of high-efficiency and high-yield rice varieties is significantly higher.The main reason for high yield of high-efficiency and high-yield varieties is the high group spikelet yield.In hybrid rice varieties,grain number per panicle with high yield is the key factor,while in high efficient and high yield japonica rice varieties,panicle number with high yield per unit area plays a greater role.The yield response of high-efficiency and High-yield hybrid rice varieties to nitrogen fertilizer is higher than that of other varieties.Under high nitrogen conditions,the yield of hybrid rice varieties could still show a higher level.High-efficiency and high-yield japonica rice varieties reach the highest yield level at medium nitrogen level,and have a relatively low dependence on high nitrogen level.Low-efficiency varieties show strong dependence on high nitrogen conditions.Late sowing led to a significant reduction in the yield of all types of varieties.High-efficiency and high-yield varieties could still achieve a higher fruiting rate under late sowing conditions,which is an important reason for high yield under late sowing conditions2.The dry matter accumulation of high-efficiency and high-yield varieties in early stage(25 days after transplanting)and fruiting stage was significantly higher than that of ordinary rice varieties,which indicates that the dry matter accumulation of high-efficiency and high-yield varieties in early and late growth stage is higher than that of ordinary rice varieties.High-efficient and high-yield varieties have faster growth of tiller in early stage,higher root oxidizing ability,higher panicle-forming rate of stem and tiller,higher efficient leaf area rate and higher net photosynthetic rate in middle and late stage of fruit setting.Root dry weight of high-efficiency and high-yield varieties is significantly higher than that of ordinary rice varieties at all growth stages.With the increase of nitrogen application,the dry matter accumulation of rice varieties increases,while the stem sheath and the transportability and transportability rate of leaves decreased.The dry matter accumulation of high-efficiency and high-yield varieties in the early stage is more sensitive to nitrogen fertilizer.The contribution rate of stem sheath and transporter to panicle is lower than that of ordinary rice varieties,but the increase of dry matter in panicle is significantly higher than that of ordinary rice varieties.The characteristics of high-efficiency and high-yield varieties are as follows:on the basis of higher group storage capacity,high-efficiency material production capacity during fruiting period can ensure fruiting and obtain higher yield level.Under the condition of late sowing,the dry matter accumulation of high-efficiency and high-yield varieties remain at a high level in the early and late growth stages3.By comparing the distribution ratio before and after earing stage,it can be seen that the days before earing of high-efficiency and high-yield hybrid rice varieties are relatively shorter than other types of varieties,and the fruiting period is relatively longer.Moreover,the daily dry matter production during the fruiting period is significantly higher than that of the ordinary types of varieties,thus showing a high level of production in fruiting period.The proportion of high-efficiency and high-yield japonica rice varieties in fruiting period is relatively stable,and the yield at fruiting stage is higher depending on higher production efficiency in later period The delayed sowing date reduces the days before earing,mainly the days between sowing and jointing.The days after earing increase slightly or remain basically unchanged,and the proportion before and after growth period decreases.Material production efficiency of high-efficiency and high-yield varieties is higher during fruiting period and still has a high level under late sowing conditions.4.The total nitrogen intake,agronomic utilization efficiency,partial productivity of nitrogen fertilizer and utilization efficiency of high-efficiency and high-yield varieties are significantly higher than those of ordinary varieties.The grain production efficiency of high-efficiency and high-yield hybrid rice varieties is significantly higher than that of ordinary rice varieties,but there is no significant difference between high-efficiency and high-yield japonica rice varieties and other varieties.The activities of NR and GOGAT in high-yield and high-yield cultivars are significantly higher than those of ordinary cultivars at the 25the day after transplantation,and the activities of GS are significantly higher than those of ordinary cultivars at all growth stages.With the increase of nitrogen application rate,the total nitrogen intake of hybrid rice varieties increases,while other nitrogen absorption and utilization indicators show a downward trend.The delayed sowing date reduces the total nitrogen intake,agronomic utilization rate,partial productivity and physiological utilization rate of nitrogen fertilizer in high-yield and high-efficiency rice varieties,and increases grain production efficiency and nitrogen intake and utilization rate.5.Apart from the high yield hybrid rice,the whole milled rice rate is significantly higher than that of the ordinary varieties,there is no significant difference in the processing quality of all types of varieties,and there is no obvious regularity in appearance quality,cooking and eating quality and RVA spectrum characteristic value among varieties.It can be seen that there is no inevitable relationship between rice quality indicators and varieties.The response of cooking and eating quality of all varieties to nitrogen fertilizer is the same,and the cooking and eating quality of all varieties is better at medium nitrogen level.The delayed sowing date has little effect on the processing quality of all varieties,and the chalkiness and chalky grain rate increases.The delayed sowing date increases amylose content and decreases gel consistency of rice,but the effects on protein content are different among varieties.Protein content of hybrid rice generally increases,while protein content of japonica rice decreases.The delayed sowing date reduces the maximum viscosity,hot slurry viscosity,final viscosity and disintegration value of all varieties,and increases the reduction value and recovery value.The performance of all types of varieties was comparatively consistent.