Responses of photosynthetic characteristics and enzyme activity of nitrogen metabolism to low nitrogen in maize with different nitrogen tolerance

Peijun Tao,Kai Xiao,Xiangling Li,Yongwei Cui,Yuechen Zhang,Pengtao Ji

doi:10.25165/j.ijabe.20201306.5891

Abstract

Understanding the physiological processes associated with leaf photosynthetic characteristics and nitrogen (N) assimilation during grain-filling stage are helpful for enhancing nitrogen utilization efficiency (NUtE) of maize. In this study, the leaf photosynthetic and N assimilation parameters in maize, including Zhengdan 958 (ZD958), a low-N tolerance cultivar and Huanong 138 (HN138), a low-N sensitive cultivar under different N rates were examined. Results showed that ZD958 displayed significant increases on grain yield and NUtE than that in HN138. Analyses on the leaf photosynthetic and N assimilation-associated processes indicated that ZD958 had higher leaf N remobilization (Rem N), net photosynthetic rate (Pn) and photosynthetic N use efficiency (PNUE) with respect to those of HN138 during grain-filling stage. In addition, ZD958 was also shown to be higher activities of leaf nitrate reductase (NR), glutamine synthetase (GS), nitrate reductase (GDH) and glutamine synthetase (GAGOT) than those of HN138. The leaf PNUE was significantly positively correlated with NR, GS, GDH, GOGAT suggesting that leaf PNUE and NR, GS, GDH, GOGAT jointly determined the N remobilization efficiency and the leaf N remobilization during post-silking. These results suggested that ZD958 possessed improved PNUE, NR and GS activities in leaves during grain-filling stage that contributes improve grain weights and yield formation capacities upon under low-N conditions. Keywords: low-N, photosynthesis, nitrogen assimilation, nitrogen utilization efficiency, maize DOI: 10.25165/j.ijabe.20201306.5891 Citation: Ji P T, Cui Y W, Li X L, Xiao K, Tao P J, Zhang Y C. Responses of photosynthetic characteristics and enzyme activity of nitrogen metabolism to low nitrogen in maize with different nitrogen tolerance. Int J Agric & Biol Eng, 2020; 13(6): 133–143.

Highlights

Nitrogen (N) is the critical limiting nutrient for most crops
This study provides insights into the N-associated physiological processes that maize species responds to N deprivation and puts forward guidance for breeding low-N tolerant and high nitrogen utilization efficiency (NUtE) maize cultivars under low-N conditions
This study showed that the GDH and GOGAT activity of leaf in Zhengdan 958 (ZD958) was higher than Huanong 138 (HN138) under low-N conditions (Figure 5)

Summary

Introduction

Nitrogen (N) is the critical limiting nutrient for most crops. Over 110 million tons of N fertilizer is applied annually to maximize crop yields. Application of N fertilizers contributes greatly to the increase of the grain protein content, biomass and economic yield of maize. Increasing maize N use efficiency (NUE) is an important approach to reduce fertilizer application and improve resource utilization efficiency. NUE is contributed by N utilization efficiency and N uptake efficiency[3]. Differences in N uptake and utilization vary significantly among genotypes[4,5], The selection of N-efficient cultivar varieties (cultivars with higher grain yield under low N condition) plays a significant role in improving the NUE[6,7]. Improvement on plant NUE through breeding high NUE cultivars together with suitable N fertilizer management can help accomplish the goal for optimized high yield

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Conclusion