| The acreage of winter wheat following rice in the middle and lower reaches of Yangtze River has reached 4 million hm2, but the average yield per unit area was lower than that in Huanghuai Plain. The average yield of wheat following rice in Jiangsu province has now been higher than 5250 kg/hm2, and even has reached 6000 kg/hm2 in some cities and counties. In some high-yielding production areas in the southern part of Jiangsu Province, the yield is higher than 8000 kg/hm2. In the middle and northern part of Jiangsu Province, the yield is even higher than 9000 kg/hm2. These have provided a practical basis for the further improvement of wheat yield in large areas. In order to explore the reproducibility of super high-yield of wheat, this study was done to investigate the population characteristics and control techniques of super high-yielding wheat. This study was carried out in Dazhong Farm, Yancheng, Jiangsu during the two wheat growing seasons from 2013 to 2015 and the physiological parameters were determined in the Key Laboratory of Crop Genetics and physiology of Jiangsu Province. Yangfumai 4, a middle gluten spring wheat variety, was used, with different combinations of spacing, planting density, and the ratio of basal to dressing of phosphorus and potassium. The objective was to investigate the yield components, population characteristics, the characteristics of photosynthesis and senescence and grain quality. Based on these, the preliminary high-yielding cultivation techniques of Yangfumai 4 were proposed. This study is of critical importance for providing a theoretical and practical basis for achieving super high yield of Yangfuimai 4. The main results were as follows:1. Under the conditions of this study, the number of spike per unit area was the utmost factor affecting grain yield of Yangfumai 4. The grain yield reached 9000 kg/hm2 when the grain number and 1000-grain-weight were coordinated. The super-yielding population was achieved when the number of spike, the number per spike and 1000-grain-weight were about 520×104/hm2,45 and 42g.2. The population quality indexes should be maintained at reasonable levels to achieve a high yield for Yangfumai 4 following rice. During wintering, the number of stem and tiller should be maintained at 6.2-6.3 million/hm"2, which is about 1.2 times as big as the final number of spike. At jointing, the number of stem and tiller should be maintained at 11.13-11.35 million/hm-2, which is about 2.1 times as big as the final number of spike. The number of spike was 45.6%～47.0% of the number of stem and tiller. At stages of booting, flowering and milk-ripening, the suitable LAI is 6.7-6.8,5.3-6.2 and 2.5-2.8, respectively. In both experimental years, the biomass accumulation after flowering was positively correlated to grain yield. The increase in the biomass accumulation after flowering is the basis of material accumulation for super high-yielding. The biomass accumulation from flowering to maturity should reach 7000 kg/hm2 to get a super high-yielding level.3. During the whole growth period, the accumulated amount of phosphorus and potassium in the super high-yielding population of Yangfumai 4 followed an S-shape trend. From emergence to jointing, the accumulated amount of phosphorus and potassium in the super high-yielding population was similar to that in the high-yielding population and medium high-yielding populations. From jointing to flowering, there was a higher accumulation of phosphorus and potassium in the super high-yielding population. At maturity, the accumulation of phosphorus and potassium in the super high-yielding population was even higher as compared with that in the high-yielding population and medium high-yielding populations.4. After flowering, SPAD reading, net photosynthetic rate, POD, SOD, CAT activity in the flag leaves of super high-yielding population were all higher than those of high-yielding population and medium high-yielding populations. The content of MDA was lower in the flag leaves of super high-yielding population as compared with that of the high-yielding population and medium high-yielding populations. The POD, SOD, CAT activity in the flag leaves at flowering and on the 7th,14th,21st,27th day after flowering were linearly positively correlated with grain yield, while the content of MDA in the flag leaves at the same time was linearly negatively correlated with grain yield at the probability levels of 0.05 or 0.01. Increase flowering flag leaf SPAD, net photosynthetic rate,POD,SOD,CAT activity and decrease flag leaf MDA content all advantageous to extend the time of photosynthesis, delay leaf senescence and improve photosynthetic efficiency finally realize yield increase.5. In summary, the row space, planting density, nitrogen rate, the ratio of basal to top dressing of phosphorus and potassium, and the ratio of nitrogen rate applied as basal, at wintering, tillering, and booting were 30 cm,1.5-1.8 million,270-360 kg/hm2,5:5 or 6:4, and 5:1:2:2 are the factors of suitable cultivation mode for achieving super high yield in Yangfumai. |
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