The SOI model of quantitative cultivation of super-high yielding rice.

【Objective】 A model of cultivation for stable yield of super-high-yielding rice was studied. 【Method】 Taking the early-maturing late-japonica varieties,Wujing 15 and Changyou 1,as materials,through the nitrogen fertilizer regimes under other cultivating conditions all being the optimal,three strategic management models of cultivation were examined,i.e. SOI (stabilizing,optimizing,intensifying during the early ,middle,late phase correspondingly to adopt the ratio of basal-tillering and panicle initiating fertilizer of 50:50 and nitrogen applying leaf age of remaining leaf primordium number of 4,3),BP (balance promoting during all phase to adopt the ratio of basal-tillering and panicle initiating fertilizer of 40:60 and nitrogen applying leaf age of remaining leaf primordium number of 5,4,3) and PC (promoting,controlling during the early,middle phase correspondingly to adopt the ratio of basal-tillering and panicle initiating fertilizer of 75:25 and nitrogen applying leaf age of remaining leaf primordium number of 5),in contrast to the CK (A model of conventional cultivation management) in field production of one-seasoned rice in the region of the middle and lower reaches of the Yangtze River. Their results were systematically compared in various aspects,such as yielding and its components,dynamics of population stems and tillers,leaf area index,photosynthetic potential,grain-leaf ratio,production of dry matter,root activity after heading,etc. In addition,confirmatory tests on the practicability of the super high yield cultivation of the SOI model on 6.7 hectares of contiguous fields,as well as comprehensive experiments in the scale of 1-3.3 hectares,were performed using other varieties,Xudao 3,Changyou 1,Lingxiangyou 18 and Wujing 15,in the areas of Donghai,Xinghua,Gaoyou and Changshu of Jiangsu. 【Result】 The yields of SOI and BP were ranking up to the level of super-high-yield(≥750 kg/667m2) in two varieties. Compared with CK,more spikelets per panicle and population spikelets were observed in the models of SOI and BP,with roughly the same level of panicles per unit area,filled-grain percentage,and 1000-grain-weight. In the models of SOI and BP in comparison with CK,the population of stems and tillers achieved the expected number punctually at the critical leaf-age for productive tillers,and reached the peak with an appropriate value (1.3-1.4 folds of expected panicle number),then decreased gently,ultimately arrived at a significantly higher rate of productive tillers to total tillers than CK. Plants in SOI and BP models developed approximately the same population LAI dynamics and dynamics of stems and tillers,their maximal LAI appeared at the booting stage (8.0-8.5) and remained a level of 3.5-4.0 at the maturity stage. As for the population photosynthesis potential and the dry matter accumulation,the models of SOI and BP showed lower values than CK during the early stages (from transplantation to jointing stage),during the middle stages (from jointing to heading) both two models were roughly the same with CK,showing no statistical significance,and for the later stages in growth and development (from heading to maturity),two models were at remarkably higher levels in these two parameters. The two models developed a nearly dry weight of roots as compared to CK at the stage of jointing,but they developed remarkably higher than CK at heading and maturity. A pattern of evidently higher values than CK in both SOI and BP was found in such parameters as the root-shoot ratio at the stages of jointing,heading and maturity,the average root exudates after heading (from heading to waxy stage),and the ratio of spikelets to root exudates. Besides,an average yield per 667m2 was achieved,both in the comprehensive super-high-yield cultivation experiment of SOI in more than 2 consecutive years,and in the confirmatory tests for practicality in the contiguous fields of 6.7 hectares. 【Conclusion】 The results revealed that the pivotal principle for super-high-yield cultivation of rice lies in'strengthening the supporting system,enlarging the sink capacity,and guaranteeing the grain-filling',and the super-high-yield cultivation mode was proposed,i.e. appropriate number of population stems and tillers with strong seedlings at early stage,high photosynthetic efficiency population structure with controlling ineffective tillers at middle stage,and enriched dry matter production with large panicles,strong stems,high efficiency leaves in proper population configuration at later stage.