Nitrogen fertilization coupled with iron foliar application improves the photosynthetic characteristics, photosynthetic nitrogen use efficiency, and the related enzymes of maize crops under different planting patterns

Jamal Nasar; Gui-Yang Wang; Shakeel Ahmad; Ihsan Muhammad; Muhammad Zeeshan; Harun Gitari; Muhammad Adnan; Shah Fahad; Muhammad Hayder Bin Khalid; Xun-Bo Zhou; Nader R Abdelsalam; Gamal A Ahmed; Mohamed E Hasan

doi:10.3389/fpls.2022.988055

Nitrogen fertilization coupled with iron foliar application improves the photosynthetic characteristics, photosynthetic nitrogen use efficiency, and the related enzymes of maize crops under different planting patterns

Front Plant Sci. 2022 Sep 2:13:988055. doi: 10.3389/fpls.2022.988055. eCollection 2022.

Authors

Affiliations

¹ Guangxi Key Laboratory of Agro-Environment and Agro-Products Safety, Guangxi Colleges and Universities Key Laboratory of Crop Cultivation and Tillage, Agricultural College of Guangxi University, Nanning, China.
² Department of Agricultural Sciences and Technology, Kenyatta University, Nairobi, Kenya.
³ Department of Agriculture, University of Swabi, Swabi, Pakistan.
⁴ Department of Agronomy, The University of Haripur, Haripur, Pakistan.
⁵ National Research Center of Intercropping, The Islamia University of Bahawalpur, Bahawalpur, Pakistan.
⁶ Agricultural Botany Department, Faculty of Agriculture (Saba Basha), Alexandria University, Alexandria, Egypt.
⁷ Plant Pathology Department, Faculty of Agriculture, Moshtohor, Benha University, Benha, Egypt.
⁸ Bioinformitics Department, Genetic Engineering and Biotechnology Research Institute, University of Sadat City, Sadat City, Egypt.

Abstract

Photosynthetic rate (Pn) and photosynthetic nitrogen use efficiency (PNUE) are the two important factors affecting the photosynthesis and nutrient utilization of plant leaves. However, the effect of N fertilization combined with foliar application of Fe on the Pn and PNUE of the maize crops under different planting patterns (i.e., monocropping and intercropping) is elusive. Therefore, this experiment was conducted to determine the effect of N fertilization combined with foliar application of Fe on the photosynthetic characteristics, PNUE, and the associated enzymes of the maize crops under different planting patterns. The results of this study showed that under intercropping, maize treated with N fertilizer combined with foliar application of Fe had not only significantly (p < 0.05) improved physio-agronomic indices but also higher chlorophyll content, better photosynthetic characteristics, and related leaf traits. In addition, the same crops under such treatments had increased photosynthetic enzyme activity (i.e., rubisco activity) and nitrogen metabolism enzymes activities, such as nitrate reductase (NR activity), nitrite reductase (NiR activity), and glutamate synthase (GOGAT activity). Consequently, intercropping enhanced the PNUE and soluble sugar content of the maize crops, thus increasing its yield compared with monocropping. Thus, these findings suggest that intercropping under optimal N fertilizer application combined with Fe foliation can improve the chlorophyll content and photosynthetic characteristics of maize crops by regulating the associated enzymatic activities. Consequently, this results in enhanced PNUE, which eventually leads to better growth and higher yield in the intercropping system. Thus, practicing intercropping under optimal nutrient management (i.e., N and Fe) could be crucial for better growth and yield, and efficient nitrogen use efficiency of maize crops.

Keywords: PNUE; enzymatic activities; intercropping; iron; nitrogen; nitrogen use efficiency; photosynthetic rate.