关键词: 稻茬小麦, 高产高效协同, 群体质量特征, 氮素吸收特征, 技术途径

Abstract:

【Objective】This study aimed to provide the theoretical and technical support for the synergic cultivation of good-quality, high-yield, and high-efficiency of wheat under the rice-wheat rotation. 【Method】 In 2017-2018 and 2018-2019, the cultivation patterns of tradition (TCP), high yield (HCP), reducing fertilizer (RFCP), and reducing fertilizer and increasing planting density (IDCP) were conducted in Suining (northern Jiangsu) and Hanjiang and Yangzhou (middle area of Jiangsu) to study the differences in grain protein content, grain yield, nitrogen efficiency, and economic benefits. The excepted results could clarify the patterns achieving high yield and high efficiency and the characteristics of their wheat population qualities and nitrogen absorption and transportation, explore the relationship between yield, nitrogen efficiency and agronomic physiological traits, and then reveal the approaches to realize high yield and high-efficiency synergy. 【Result】 The effects of cultivation patterns on wheat grain yield, net economic benefit, and nitrogen efficiency were different depending on the ecological conditions in the various years and sites. The wheat grain protein content under different cultivation patterns was more than 12.5%, but which under HCP and RFCP was 13%-14%. In 2018, IDCP achieved the highest grain yield and economic net benefit with 31.5%-33.5% and 104.4%-239.1% higher than TCP, respectively, followed by HCP and RFCP. In 2019, the grain yield under HCP was the highest, which was 8.1%-13.2% higher than that under TCP, followed by RFCP and IDCP. In addition, IDCP could obtain stable or increased net economic benefits compared with TCP because of less fertilizer inputs. The above results indicated that compared with other patterns, grain yield, nitrogen efficiency, and economic benefits under TCP were relatively lower. HCP could achieve more stable and higher grain yield as well as higher protein content, and IDCP achieved the highest yield potential, economic benefits, and nitrogen efficiency but had a low grain protein content. High yield was achieved by increasing single-spike yield based on enough spike number, and the high yielding HCP mainly increased grains per spike, but IDCP achieved high grain weight. HCP achieved high spike number mainly depended on tiller fertility, and IDCP depended on the synergistically increasing tiller number and tiller fertility. The suitable range of the ratio of tiller number at the beginning of wintering stage to spike number was 0.9-1.1 for high yield population. Further analysis showed that the high yield patterns could improve the leaf photosynthetic rate and maintain a high photosynthetic area after anthesis, indicating high-level coordination of the source-sink relationship and enlarged source level. The results also indicated that improving nitrogen absorption efficiency based on high nitrogen physiological efficiency was the key for realizing high nitrogen use efficiency. The nitrogen accumulation in the HCP population was low at the early growth stage, but the absorption capacity was gradually increased at the middle and late growth stage, finally promoting nitrogen transportation. The IDCP population also had strong nitrogen absorption capacity during the middle and early growth stage and also showed a sufficient transportation level. The relationships of grain yield and nitrogen use efficiency with agronomic and physiological traits under different ecological conditions and cultivation patterns were analyzed, and it was found that increasing tiller fertility of the crop population contributed to a higher photosynthetic area per stem and leaf photosynthetic rate at the grain-filling stage, which increased single-spike yield and wheat production. Besides, the high tiller fertility also promoted nitrogen absorption capacity before anthesis increasing nitrogen transportation and use efficiency. 【Conclusion】 In conclusion, the synergistic approach to achieve high yield and high efficiency of wheat under the rice-wheat rotation was to develop large spikes especially increase grain weight based on obtaining sufficient spikes and to establish the population with sufficient quantity and high quality. The latter included that the tiller number of the population before wintering stage met the expected spike number with improving tiller fertility, the nitrogen absorption and transportation level was high before the anthesis stage, and the photosynthetic area and intensity of single stem could maintain a high level after the anthesis to promote the grain filling. The present study also indicated that technologies realizing high-yield and high-efficiency production needed to emphasize moderately increasing planting density, limitedly reducing nitrogen application, increasing topdressing nitrogen with reducing base fertilization, and precisely applying fertilization.

Key words: wheat under rice-wheat rotation, high-yield and high-efficiency synergy, population quality characteristics, nitrogen uptake characteristics, technological approach