Abstract
Better management of N fertilizer is essential for improving crop productivity. Wheat (Triticum aestivum L.)–peanut (Arachis hypogaea L.) relay intercropping rotation systems are a mainstay of the measures to improve the economic and food security situation in China. Therefore, a 2-year field study (2015–2017) was conducted to evaluate the effect of different N fertilizer management regimes on the photosynthetic characteristics and uptake and translocation of N in peanut in the wheat–peanut rotation system. We used common compound fertilizer (CCF) and controlled-release compound fertilizer (CRF) at the same N–P2O5–K2O proportion (The contents of N, P2O5, and K2O in the two kinds of fertilizer were 20, 15, and 10%, respectively.). The fertilizer was applied on the day before sowing, at the jointing stage or the flag leaf stage of winter wheat, and at the initial flowering stage of peanut in various proportions, with 0 kg N ha-1 as the control. Results showed that split applications of N significantly increased leaf area index (LAI) and chlorophyll content and improved photosynthetic rate, thus increasing the pod yield of peanut. Topdressing N at the jointing stage (S1) or at the flag leaf stage of wheat (S2) and supplying part of the N at the initial flowering stage of peanut increased pod yield. Withholding N until the flag leaf stage (S2) did not negatively affect wheat grain yield; however, it increased N accumulation in each organ and N allocation proportions in the peanut pod, ultimately improving pod yield. With the same N–P2O5–K2O proportion and equivalent amounts of nutrient, CRF can decreased malondialdehyde (MDA) and maintain a relatively high LAI and chlorophyll content at the late growth stage of peanut, prolong the functional period of peanut leaves and delay leaf senescence, resulting in an increase of pod yield over that with CCF. At S1, CRF resulted in a better pod yield than CCF by 9.4%, and at S2 it was 12.6% higher. In summary, applying N fertilizer in three splits and delaying the topdressing fertilization until the flag leaf stage of winter wheat increases total grain yields of wheat and peanut. This method could therefore be an appropriate N management strategy for wheat–peanut relay intercropping rotation systems in China.
Highlights
Nitrogen fertilizers contain important nutrients and have supported the rapidly expanding population of the world by increasing crop production during the last few decades (Tilman et al, 2011)
When applying N at the jointing stage (S1), the leaf area index (LAI) resulting from JCF70 and JCRF70 at different stages was increased by 7.6–11.8 and 14.3–26.9%, respectively, compared to that under JCF100, while by withholding N till the flag leaf stage (S2), the LAI under FCRF70 and FCF70 at different stages was increased by 5.1–12.5 and 15.3–25.1%, respectively, compared to that under FCF100
Our study showed that splitting the application of N and withholding N resulted in an improved Nitrogen harvest index (NHI) in peanut: the NHI of JCF70 was higher than under JCF100 by 4.3%, while the NHI of FCF70 was higher than that for FCF100 by 4.5% (Table 5), indicated that splitting and withholding the application of N could meet the growth and development needs of peanut when large amounts of nutrients are consumed during the wheat season under the wheat–peanut relay intercropping rotation systems
Summary
Nitrogen fertilizers contain important nutrients and have supported the rapidly expanding population of the world by increasing crop production during the last few decades (Tilman et al, 2011). The Northern China Plain and the Huang-Huai-Hai Plain are major producers of wheat (Triticum aestivum L.) and peanut (Arachis hypogaea L.), contributing approximately 68% of the total wheat grain yield (Wang et al, 2009) and 60% of the national area producing peanut, constituting an important basis for the maintenance of a stable vegetable oil market (Guo H.H. et al, 2010) In this region, the wheat–peanut relay intercropping rotation system is a successful crop management strategy that is widely practiced by farmers because it can improve economic efficiency, in the provinces of Henan and Shandong. Under such conditions, the preceding crop (i.e., the wheat) consumes a large amount of nutrients during the whole growth period, and the deficiency in soil fertility after the wheat harvest results in insufficient nutrients in the soil for peanut to grow at the middle and late growth stages, causing a low peanut yield (Liu et al, 2017)
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