Study On High Yield Formation And Cultivation Strategies Of Late Japonica Rice In Double-cropping Rice Area

In order to study the productive advantages and formation mechanisms of late japonica rice, experiments were carried out during year2009-2011with six japonica (Wuyunjing24, Nanjing44, Zhendao11, Changyou1, Changyou5, Yongyou8) and five indica (Huanghuazhan, Ganwanxian30, Yueyou9113, Tianyouhuazhan, Wuyou308) rice varieties in the double-cropping rice area in Poyang and Shanggao of Jiangxi province respectively. To study the formation rule of super high yield of the late japonica rice in the double-cropping rice area, using Yongyou8as material during2011-2012in Shanggao of Jiangxi province, the grain yield and its characteristics of three types of populations (High Yield:8.25-9.75tha-1; Higher Yield:9.75-10.50t ha-1; Super High Yield:>10.50t ha-1) were analyzed. During2010-2012, accoding to the objective requirements of various cultivation methods and local stubbles, the five cultivation methods of artificial transplanting (AT), ordered transplanting (OT), optimized broadcasting(OB), cast transplanting(CT) and mechanical transplanting (MT) were carried out with the Wuyunjing24, Zhendao11,Changyou5, Yongyou8and Yongyou12as materials, a comparative study of cultivation methods on yield formation, growth stage and utilization of temperature and illumination of late japonica rice was conducted respectively. During2011-2012, with C hangyou5and Yongyou8as materials, seven different proportions of base-tillering fertilizer to panicle fertilize(10:0,8:2,7:3,6:4,5:5,4:6,3:7) were designed in Shanggao, to research the nitrogen applied methods of late japonica rice. The main results were as follows:(1) The average yield of late japonica rice in three years were9.6,8.3,9.9t ha-1respectively, were higher than indica rice significantly, which the yield of Yongyou8was10.61ha-1in2011, grains per panicle, seed-setting rate and1000-grain weight of japonica rice were higher than indica rice, which was the key point of harvesting high yield of japonica rice. Milling quality, cooking and eating quality of japonica rice were better than indica rice significantly, while appearance and nutritional quality followed an opposite tendency accordingly. Brown rice rate, milled rice rate, and head rice rate were significantly or very significantly higher than indica rice; the amylase content, protein content were significantly or very significantly lower than indica rice; gel consistency was longer. The appearance quality was slightly worse than the indica rice; the chalky grain rate of japonica rice was very significantly higher than indica rice, but the chalkiness area and degree showed no significant difference. The benefits of late japonica rice were significantly higher than that of indica rice; The net output value in three years were16382.7yuan ha-1,15035.4yuan ha-1,21731.2yuan ha-1, was higher than indica20.1%,20.4%,24.6%respectively; the net income was11891.6yuan ha-1,10252.1yuan ha-1,16565.9yuan ha-1respectively, was higher than indica rice23.8%,23.6%,26.7%, differences were significant or very significant. The physiological ecological characteristics of productive advantages of late japonica rice in double-cropping rice area were as follows. Firstly, growth duration of japonica rice was longer than indica rice significantly and japonica rice was more adapted to cool weather at the later period of grain filling, increasing utilization of temperature and solar radiation and ensuring japonica rice maturing safely. Secondly, strong photosynthetic capacity of japonica rice at the later period increased dry matter weight and total filling. Thirdly, japonica rice improved the resistance to cold and premature senescence, and lodging due to strong root, stem and sheath.(2) Results showed that population of supper high yield had more panicle and spikelets per panicle than high yield and higher yield. There was no significant difference in filled-grain percentage and1000-grain weight between the three populations. Population of supper high yield exhibited more tillers at the transplanting stage and achieved excepted number of stems and tillers at critical leaf-age for productive tillers, whose max number of stems and tillers were at jointing stage and were fewer than excepted number. Then, the number of population stems and tillers began to decrease stably, which achieved expected number again. At last, ratio of productive tillers to total tillers of supper high yield population was about78.0%, which was higher than that of population of high and higher yield. The leaf area index of supper-high-yield population was lower than that of high and higher yield population at the early growth stage, and the max leaf area index was about8.3at booting, which decreased stably and was above3.5at maturity. The photosynthetic potential of population with supper-high-yield was small at early stage and larger at middle and late stages, as compared with population of the high and higher yield; the photosynthetic potential was above300×104m2d ha-1from heading to maturity, the total photosynthetic potential was above675×104m2d ha-1. The dry matter accumulation was smaller than the population of high and higher yield before jointing, and the weight was increasing faster after jointing, the dry matter accumulation was about10.5t ha-1at heading, which was significantly higher than that of population of high and higher yield. The total weight of dry matter was about19.0t ha-1, translocation ratio of output was above14.5%. The weight of dry matter of root and root-shoot ratio at each growth stage, root bleedings were higher than the high and higher yield; the N content and N uptaking were also higher. Based on the formation of the japonica rice, the regulation approaches and key cultivation techniques for raising the super-high-yield population were discussed.(3) Compared with the AT, the growth periods CT and MT were delayed, and their total growth periods were significantly shortened by4.9and10.3days. For different types of varieties, the shortened day of late japonica was more than that of medium japonica. For the same mature period types, the shortened day of japonica hybrid rice was more than that of japonica conventional rice. The utilization efficiency of accumulated temperature and light time of various types of varieties at different developmental stages showed that AT>CT>MT, and the whole growth period trended similarly. The utilization efficiency of temperature and light in the whole growth period under MT was only85.66%and80.75%. On the basis of the above results, preliminary division for the suitable range and its supporting suitable variety types of different cultivation methods was made. AT, CT and MT were all suitable in this area, but each cultivation method had its suitable variety types.Compared with the MT, HT, OT, OB and CT increased grain yield by16.8%-17.1%,11.7%-12.7%,5.4%-5.9%and1.8%-3.6%, respectively. Compared with the MT, the HT, OT, OB and CT also significantly increased percentage of productive tillers, efficient and high efficient leaf area, grain-leaf ratio, photosynthetic potential, CGR and NAR, production and accumulation of the biomass in the growth and development stage, and root bleeding after heading were greater than MT; the index of plant type of the other cultivations was better than MT. The differences of population with different cultivations were mainly due to the different durations of vegetative growth period. The results indicated that the population quality of rice could be improved and higher yield could be achieved through integrating and optimizing cultivation techniques in late japonica rice production in the double-cropping area.(4) Results showed that, the ratio of basic and tillering fertilizer to total nitrogen to high yield and apparent nitrogen recovery efficiency of late japonica was from60%to70%in the south douuble-cropping rice area. Using this ratio, made more panicles and spikelets per panicle, larger total spikelets and stable filled-grain percentage and1000-grain weight, and lower max number of stems and tillers, higher ratio of productive tillers to total tillers, max LAI, LAD, higher dry matter accumulation in population growth and development, got the higher actual yield ultimately. The nitrogen uptaking and utilization, compared with other treatments, there was more significantly accumulated amount of the absorbed nitrogen, higher apparent nitrogen recovery efficiency, agronomic nitrogen use efficiency and yield of ear nitrogen, but lower nitrogen requirement for100kg grain. The quality of rice, there were better milling quality, improving the cooking, eating and nutritional quality, but the appearance quality got worse, the RVA profile characters could not achieve the best at the same time; On the whole, the ratio of basic and tillering fertilizer to total nitrogen from60%to70%might realize the coordination of supper high-yield, good quality and high nitrogen use efficiency.