Timing of N Application Affects Net Primary Production of Soybean with Different Planting Densities

作     者：ZHANG Ming-cong SUN Wen-xiang LIU Yuan-ying LUO Sheng-guo ZHAO Jing WU Qiong WU Zhen-yu JIANG Yi 

作者机构：Resource and Environment College Northeast Agricultural University 

出 版 物：《Journal of Integrative Agriculture》 (农业科学学报（英文版）)

年 卷 期：2014年第13卷第12期

页      面：2778-2787页

核心收录：

学科分类：09[农学] 0901[农学-作物学] 

基　　金：financially supported by the Special Fund for Agro-Scientific Research in the Public Interest, China (201103003) the Key Technologies R&D Program of China during the 12th Five-Year Plan period (2012BAD20B04) 

主　　题：soybean starter-N plus topdressing N density leaf area index (LAI) net assimilation rate (NAR) 

摘      要：Understanding the relationship between the timing of N fertilizer applications and crop primary production is crucial for achieving high yield and N use efifciency in agriculture. This study investigated the effects of starting-N plus topdressing N applications （as compared to the common practice of all basal application） on soybean photosynthetic capacity under different planting densities. A ifeld experiment was conducted in two growing seasons （2011 and 2012）, and the soybean （Glycine max L. Merrill） cultivar was Dongnong 52, three planting densities （20, 25 and 30 plants m-2）, and four N fertilizer application patterns （all N fertilizer of 6 g N m-2 as basal fertilizer, all N fertilizer as topdressing at beginning pod stage （R3）, 1.8 g N m-2 as basal fertilizer and 4.2 g N m-2 as topdressing at stage R3 and full pod stage （R4）, respectively）. The results indicated that under the same planting density, compared to applying all N as basal fertilizer, the application of starter-N plus topdressing N substantially reduced the rate of pod abscission, and enhanced leaf area index （LAI） signiifcantly at beginning seed stage （R5） （P〈0.05）, net assimilation rate （NAR） during stages R4-full seed stage （R6） （P〈0.05）, contribution rate of post-seed iflling assimilate to seed （CPA） （P〈0.05）, and yield （P〈0.05）. Applying topdressing N at stage R4 resulted in higher net primary production and yield than applying topdressing N at stage R3. When applying starter-N plus topdressing N at planting density of 25 plants m-2, LAI after stage R5 and NAR after stage R4 were increased by 5.92-16.3%（P〈0.05） and 13.7-26.6%（P〈0.05） with the planting density of 20 plants m-2, respectively, and yield was 8.46-14.0%（P〈0.05） higher than that under 20 plants m-2. When planting density increased to 30 plants m-2, only LAI during stages R4-R5 and NAR during stages R4-R5 increased by applying starter-N plus topdressing N, while the other indexes declined. Overall, results of this study demonstrated