| Wheat is the second major cereal crop in the southern part of Jiangsu Province. The average yield of wheat is 5000 kg/hm2 in this region, which is lower than the provincial average level. The grain yield has been more than 6000 kg/hm2 in the regions of central and northern Jiangsu Province. The gap between the yield in the southern part of Jiangsu Province and in the regions of central and northern Jiangsu Province was 1000 kg/hm2. At the same time, the average yield of wheat has been more than 6000 kg/hm2 in 2015 and the yield of high-yielding.demonstration has been more than 8000 kg/hm2 in Yixing, a city in the region of southern Jiangsu, Province. The above mentioned data could explain there was still a huge potential for increasing the yield of wheat following rice in the region of southern Jiangsu Province. This study was conducted on both Agricultural Experiment Station and Vegetable and Horticulture Farm in Zhangjiagang during the two wheat growing seasons from 2013 to 2015. Yangmai16, a medium-gluten wheat variety, and Yangmai13, a weak-gluten wheat variety, which were widely planted in the region of southern Jiangsu Province, were used as the test varieties. The objective of this study was to investigate the characteristics of grain yield, yield components, population quality, the accumulation of nutrient element and physiological activity of flag leaf in different types of wheat under the condition of suitable sowing (sowing in early November) and late sowing (sowing around 20th November), using different combinations of planting density and nitrogen rate. At the same time, a high-yielding demonstration by using high-yielding cultural techniques and a questionnaire with a view to investigating the barriers hindering wheat production were used to analyze different cultivation techniques of the medium and weak gluten wheat which were suitable for the local area. The study was helpful to provide a theoretical basis and a technical support for high-yielding cultivation in the region of southern Jiangsu Province. The main results were as follows:1. Under the experimental conditions, the number of spikes is the utmost factor affecting wheat yield in the region of southern Jiangsu Province. On the base of suitable number of ears, the coordination of 1000-grain-weight and the number of grain per spike achieved stable high-yielding. Under the condition of suitable sowing, the number of spike, the number of grain per spike, and 1000-grain-weight of the high-yielding population of Yangmai16 and Yangmai13 should be kept at 475～495 ×104/hm2,42～44,42.5-45 g and 450-480x104/hm2,41～44,42～45 g, respectively. Under the condition of late sowing, the number of spike, the number of grain per spike, and 1000-grain-weight of the high-yielding population of Yangmai16 and Yangmai13 should be kept at 450～495×104/hm2,40～42,42.5～45 g and 455～495×104/hm2,41.5～44.5, 40～42.5 g, respectively.2. The differences in population quality indexes were caused by different sowing periods. Under the condition of suitable sowing, the LAI of the high yield population of Yangmai16 and Yangmail3 at the stages of overwintering, jointing, booting, anthesis and milk-ripening were 0.35～0.8,4.3～4.8,7.4～7.9,6.1～6.5,4.3～4.7 and 0.3～0.75,3.9～4.7,6.3～7.5,4.3～6.9,3.1～4.8, respectively. Besides, the dry matter accumulation amount at the stages of anthesis, maturity and post-anthesis were 13800～14800 kg/hm2,19800～21000 kg/hm2,6000～6200 kg/hm2 and 10000～15100 kg/hm2,16000～22000 kg/hm2,5800-6900 kg/hm2, respectively. Under the condition of late sowing, the LAI of the high yield population of Yangmai16 and Yangmai13 at the stages of overwintering, jointing, booting, anthesis and milk-ripening were 0.15-0.25, 4.5～5.1,7.0～7.8,5.3～6.9,3.5～4.5 and 0.15～0.2,4.5～5.6,6.9～7.9,5.8～6.65,3.0～4.0, respectively. Besides, the dry matter accumulation amount at the stages of anthesis, maturity and post-anthesis were 13200～14800 kg/hm2,19000～21000 kg/hm2,5600～6300 kg/hm2 and 13500-14300 kg/hm2,19000～20000 kg/hm2,5500～6000 kg/hm2, respectively.3. Compared with other modes, SPAD reading, photosynthetic rate (Pn) and the post-anthesis activities of CAT, POD and SOD in the flag leaves in the high-yielding model of Yangmai16 and Yangmai13 were higher and decreased slower, but MDA content in the high-yielding cultivation modes of Yangmai16 and Yangmai13 was lower.4. The stages from jointing to anthesis were the main nitrogen accumulation period of Yangmai16 and Yangmai13. Compared with other modes, the nitrogen accumulation amount in the high-yielding modes of Yangmai16 and Yangmai13 were higher. Under the condition of suitable sowing, the nitrogen accumulation amount in the high-yielding modes of Yangmai16 and Yangmai13 were 240 kg/hm2 and 216 kg/hm2 in the whole growth stage, respectively. The nitrogen utilization efficiency in terms of grain yield and the nitrogen harvest index were lower in the high-yielding cultivation modes of Yangmai16. Nitrogen utilization efficiency in terms of grain yield was higher but the nitrogen harvest index was lower in the high-yielding cultivation modes of Yangmail3. Under the condition of late sowing, the nitrogen accumulation amount in the high-yielding modes of Yangmai16 and Yangmai13 were 235 kg/hm2 and 226 kg/hm2 in the whole growth stage, respectively. The nitrogen utilization efficiency in terms of grain yield and the nitrogen use efficiency in terms of biomass accumulation were lower, and at the same time the nitrogen harvest index was higher in the high-yielding cultivation modes of Yangmai16. The nitrogen utilization efficiency in terms of grain yield, the nitrogen use efficiency in terms of biomass accumulation and the nitrogen harvest index was higher in the high-yielding cultivation modes of Yangmai13.Compared with other modes, the ratio of soluble sugar to nitrogen was higher at booting stage and lower at maturity stage in the high-yielding modes of Yangmai 16 and Yangmai13.5. Under the condition of suitable sowing, planting density, nitrogen amount, and the ratio of nitrogen application at the stages of seeding, tillering, jointing and booting should be maintained at 270×104/hm2,270 kg/hm2, and 5:1:2:2 in Yangmai 16 and 225×104/hm2,270 kg/hm2 or 270×104/hm2,225 kg/hm2 and 5:1:2:2 in Yangmai13 sown in early November to achieve stable high-yielding. Under the condition of late sowing, the high-yielding cultivation modes of Yangmai 16 and Yangmai 13 sown on November 20 were the combination of planting density 270×104/hm2 or 320×104/hm2 and 310×104/hm2, nitrogen amount 180-225 kg/hm2 and 225 kg/hm2, nitrogen applied ratio of basal:tillering:jointing:booting 5:1:2:2, respectively.6. To increase grain yield, the problem of unsuitable sowing rate and excessive nitrogen application in the region of southern Jiangsu Province should be solved. |
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