Improving maize's N uptake and N use efficiency by strengthening roots' absorption capacity when intercropped with legumes

Benchuan Zheng; Xiaona Zhang; Ping Chen; Qing Du; Ying Zhou; Huan Yang; Xiaochun Wang; Feng Yang; Taiwen Yong; Wenyu Yang

doi:10.7717/peerj.11658

Improving maize's N uptake and N use efficiency by strengthening roots' absorption capacity when intercropped with legumes

PeerJ. 2021 Jun 23:9:e11658. doi: 10.7717/peerj.11658. eCollection 2021.

Authors

Benchuan Zheng^#^{1

2}, Xiaona Zhang^#^{1

2}, Ping Chen^{1

2}, Qing Du^{1

2}, Ying Zhou^{1

2}, Huan Yang^{1

2}, Xiaochun Wang^{1

2}, Feng Yang^{1

2}, Taiwen Yong^{1

2}, Wenyu Yang^{1

2}

Affiliations

¹ College of Agronomy, Sichuan Agricultural University, Chengdu, China.
² Sichuan Engineering Research Center for Crop Strip Intercropping System/Key Laboratory of Crop Ecophysiology and Farming System in Southwest, Ministry of Agriculture, Chengdu, China.

^# Contributed equally.

Abstract

Maize's nitrogen (N) uptake can be improved through maize-legume intercropping. N uptake mechanisms require further study to better understand how legumes affect root growth and to determine maize's absorptive capacity in maize-legume intercropping. We conducted a two-year field experiment with two N treatments (zero N (N0) and conventional N (N1)) and three planting patterns (monoculture maize (Zea mays L.) (MM), maize-soybean (Glycine max L. Merr.) strip intercropping (IMS), and maize-peanut (Arachis hypogaea L.) strip intercropping (IMP)). We sought to understand maize's N uptake mechanisms by investigating root growth and distribution, root uptake capacity, antioxidant enzyme activity, and the antioxidant content in different maize-legume strip intercropping systems. Our results showed that on average, the N uptake of maize was significantly greater by 52.5% in IMS and by 62.4% in IMP than that in MM. The average agronomic efficiency (AE) of maize was increased by 110.5 % in IMS and by 163.4 % in IMP, compared to MM. The apparent recovery efficiency (RE) of maize was increased by 22.3% in IMS. The roots of intercropped maize were extended into soybean and peanut stands underneath the space and even between the inter-rows of legume, resulting in significantly increased root surface area density (RSAD) and total root biomass. The root-bleeding sap intensity of maize was significantly increased by 22.7-49.3% in IMS and 37.9-66.7% in IMP, compared with the MM. The nitrate-N content of maize bleeding sap was significantly greater in IMS and IMP than in MM during the 2018 crop season. The glutathione (GSH) content, superoxide dismutase (SOD), and catalase (CAT) activities in the root significantly increased in IMS and IMP compared to MM. Strip intercropping using legumes increases maize's aboveground N uptake by promoting root growth and spatial distribution, delaying root senescence, and strengthening root uptake capacity.

Keywords: Antioxidant enzyme activity; Maize-peanut strip intercropping; Maize-soybean strip intercropping; Nitrogen; Root bleeding sap intensity; Root distribution.

Grants and funding

This work was supported by the National Natural Science Foundation of China (31872856) and the National Key Research and Development Program of China (2016YFD030020205). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.