| In this paper, a special high yield eco-site, Taoyuan, Yunnan province, was taken as reference field base. A series of field experiments was launched including rice variety comparison, N rate, transplanting density in2005-2008to reveal the yield formation mechanism for high yield at special high-yielding eco-site and the common characteristics of rice for super high yield among different eco-sites. The technique theory and approach of precision quantative cultivation for special high yield eco-site was discussed. Results are as follows:1. Difference of yield formation and common characteristics of high yield for different eco-sitesDifferent density experiment was carried out at8typical ecosites in China to explore the rice population quantity characteristics. Results showed that growth stage, yield components, source and sink capacity, grain/leaf, plant types, dry matter accumulation and distribution differs greatly between different ecotype rice varieties. Yield was closely positive related with source capacity. Enhancement of source capacity was the main approach to improve yield potential through the increase of grain/leaf and establishment of optimum LAI. Although the contribution of dry matter accumulation around heading to yield varied greatly with varieties, the increase of dry matter accumulation after heading was benefit for the improvement of yield.2. Mechanisms of rice yield formation at high yield eco-siteThe yield were higher at Taoyuan than Nanjing, and average yield of all varieties at Taoyuan was96%and85%higher than Nanjing in2006and2007, respectively. The highest yield of18.5t ha-1was achieved by Eryou107at Taoyuan in2006. The higher yield in taoyuan were mainly attributed to:(1) physiological factor, the higher biomass accumulation with equal HI, the larger sink size mainly caused by the greater number of panicles per m2, maximum LAI with10,60%higher than Nanjing; higher N accumulation with lower amounts of N to produce100kg grain (NPAG) and equal SLN with Nanjing;(2) Ecological factor:the intense solar radiation with suitable RUE, the large diurnal temperature range and suitable temperature in whole rice growth stage;(3) morphological factor smaller area per stem, shorter, wider and thicker leaves and smaller leaf angles, low specific leaf weight and light extinction coefficient.3. Traits of plant type for high yield riceField experiments with53and48new indica cultivars were carried out in Taoyuan, Yunnan province, in2007and2008, respectively. In addition, two typical indica rice varieties with similar yield potentials, Ⅱyou107as large-panicle-type and Xieyou107as heavy-panicle-type, were planted both there and in Nanjing, Jiangsu province, in2006to2008. The results showed that the yield potential of the tested varieties in2007and2008was normal distributed with average13.69t ha-1and15t ha-1, separately. Growth duration, LAI, panicles per m2and spikelets per m2were all significant and positively correlated with grain yield at0.01level in both years. Yield potential varied greatly with sites but little with years. The correlation and path coefficient with grain yield was the highest for panicle number per m2, then the spikelet per panicle, grain weight and spikelet filling rate. Plant height, spikelets per panicle, spikelets fertile percentage and1000grain weight were stable variety traits, and little affected by site and year, while growth duration (mainly for days before heading) and panicle number were significantly varied with the sites. The yield potential can be improved by increasing the days before heading, strengthening source capacity and enlarging sink size. The optimum traits for super high yield of more than17t ha-1were (1) longer crop growth duration no shorter than155days;(2)110-125cm plant height;(3)300-400panicles per m2;(4)200spikelets per panicle;(5) about90%grain filling;(6)29-31mg grain weight.3. Parameter of N rate quantification for high yieldDifferent N rate experiment was carried out both at nanjing and Taoyuan in2008and2009with Ⅱyou107to compare the effect of N rate on rice population quality and yield components. Results showed that effect of N rate on sink and source size, plant type and dry matter accumulation at Taoyuan was superior to Nanjing. With the increasing N rate, Leaf SPAD value, N accumulation (NA), N accumulation rate (NAR) and amounts of N to produce100kg grain (NPAG) increased, and NUE decreased, while no change for NAR. NA at different development stage was higher at Taoyuan than Nanjing, but NAR at vegetative stage was lower than Nanjing. Agronomic efficiency of N and partial factor productivity (PFP) was larger at taoyan than Nanjing, and AEN, PFP under high N rate at taoyuan was twice and1.5times of Nanjing, respectively, while recovery efficiency of N (RN) and NHI differs little. Soil N supply at Nanjing was100kg ha-1while120-150kg ha-1at taoyuan. Under high yield cultivation, NPAG was1.90kg100kg-1at Nanjing and1.60kg100kg-1at Taoyuan, but the RN at both sites was same with45%. The maximum yield (10t ha-1at Nanjing and18t ha-1at Taoyuan) could be obtained with N rate of195kg ha-1at Nanjing and375kg ha-1at Taoyuan, respectively.4. Basic seedling quantitative model and effect of density on yield formationThe general formula of panicle number per plant (ES) for rice and establish the function of theoretic number of tillers for effective tillering leaf position, and determine the tiller surviving rate of seedling (s), tiller emerging rate after transplanting (r), missing tiller number after transplanting (bn), and adjusting factor (a) was summarized. Field experiments were performed in the special high-yield area at Taoyuan, Yongsheng County, Yunnan province, and tiller number and grain yield were determined. Five transplanting density treatments were conducted with an Indica hybrid rice variety, Eryou107, in2005; and six Indica hybrid rice varieties, Eryou107, Eryou318, Eryou7954, Eryou084, Eryouhang1hao and Xieyou107, were used for high-yield field experiment in2005and2006respectively. All varieties followed the "n-3" law of synchronously emerging of tiller with leaf. The theoretic number of tillers for effective tillering leaf position (A) was calculated as the function of the number of effective tillering leaf position (E). E was related with the total leaf number (N), leaf age at transplanting (SN), elongated node number (n), missing tiller number after transplanting (bn) and adjusting factor(a), E=(N-n-SN-bn-a). The adjusting factor (a) for super high-yield rice should be taken as1.5. For traditional wet-bed seedling, bn was1.5, surviving rate of tillers with2leaves (s2) was0.8, surviving rate of tillers with1leaf (s1) was0.3; while for seedling tray, bn was0.5, S2was1.0, s1was0.5. From seedling recovering to stage of tiller equal panicle, r was80%or so. For traditional wet-bed seedling, E=(N-n-SN-3), ES=(1+t3+0.8t2)(1+0.8A)+0.3t1; for seedling tray, E=(N-n-SN-2), ES=(1+t3)(1+0.8A3)+t2(1+0.8A2)+0.5t1, where t1, t2, t3represents the tillers with1,2and3leaves respectively, A2, A3represents the emerged tiller number after transplanting for tillers with2and3leaves separately. The comparison of theoretical and actual tiller number showed that the formula well depicted the tiller emergence characteristics in super-high yield rice.Effect of transplanting density on rice population quality and yield varied with the variety and ecosites. The design of wide row space and narrow plant space could improve yield through the increase of sink size, CGR after heading and dry matter accumulation. However, reduced transplanting number of hills together with increased seedling numbers per hill could decrease the yield due to the unbalanced population... |
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