Studies On Comprehensive Productivity Of Different Types Of Late Rice In Double-cropping Rice Area

The field experiments were conducted in the outside experimental base of agriculture college of Yangzhou university in Shanggao County, Jiangxi Province in 2013—2014, with indica-japonica hybrid rice, japonica hybrid rice, japonica conventional rice and indica hybrid rice as materials in double-cropping rice areas in the middle reaches of the Yangtze River. Differences of yield and its components, growth stage and utilization of temperature and illumination, population characteristics and rice quality of rice cultivars with different types were studied systematically using wet nursery and big seedlings transplanting under high-yielding cultivation condition. The result will provide the scientific basis and technical support for the selection of suitable cultivars and high-yielding cultivation in double cropping systems. The main results were as follows:1. The yields of different types of rice cultivars under the late rice of double cropping systems all demonstrated that indica-japonica hybrid rice> japonica hybrid rice> japonica conventional rice> indica hybrid rice very significantly. That building the enough total spikelets through adequate panicles and the large spikelets per panicle, and keeping a sustainable seed-setting rate and 1000-grain weight was a basic way to obtain the highest yield for indica-japonica hybrid rice. Compared with indica hybrid rice, the growth periods of indica-japonica hybrid rice, japonica hybrid rice and japonica conventional rice were delayed, and their total growth periods were significantly extended by 15.4,13.8 and 10.8 days, respectively. And the utilization efficiency of temperature and illumination of various types of rice cultivars at different developmental stages showed that indica-japonica hybrid rice was the highest, then were japonica hybrid rice and japonica conventional rice, indica hybrid rice was the lowest, and the whole growth period trended similarly among which indica-japonica hybrid rice were 3732.11℃,921.1 h,91.9% and 92.4% respectively.2. Compared with japonica hybrid rice, japonica conventional rice and indica hybrid rice, indica-japonica hybrid rice showed fewer tillers at the early growth stage, achieved expected number of stems and tillers at the critical leaf age for productive tiller, and had lower number of peak tiller at the jointing stage. Then, the indica-japonica hybrid population had a steady decline in number of tillers and had higher productive tillers rate (about 73.19%). The leaf area index of indica-japonica hybrid rice population was lower at the early growth stage, with the maximum leaf area index of about 7.93 at booting, and stably decreasing to above 3.85 at maturity, whose leaf area index, the ratio of effective leaf area, the ratio of effective leaf area and the ratio of grain to leaf were significantly higher than those of japonica hybrid rice, japonica conventional rice and indica hybrid rice population at heading. The dry matter accumulation of indica-japonica hybrid rice was comparable to that of japonica hybrid rice, japonica conventional rice and indica hybrid rice population at the critical leaf age for productive tiller and at the jointing stage, increased greater after jointing, and was higher at booting, heading, milky stage and maturity. The ratio of total biomass accumulation was higher at the middle and late growth stage. The photosynthetic potential, crop growth rate and net assimilation rate were smaller at the early stage and higher at the middle and late stages.3. Compared with indica hybrid rice, the milling quality, cooking and eating quality and nutrient quality of japonica conventional rice, japonica hybrid rice and indica-japonica hybrid rice became better, while the appearance quality became worse. The RVA profile characteristics of rice demonstrated that peak viscosity, trough viscosity, breakdown, final viscosity and peak time of japonica rice were higher than indica rice, while setback and pasting temperature followed an opposite tendency accordingly. Therefore, it is beneficial to obtain good quality characteristics to choose reasonable rice varieties types and supporting high-yielding cultivation condition in order to provide broad market value and production prospects for the implementation of "indica rice to japonica rice".