Effect of N on Growth, Antioxidant Capacity, and Chlorophyll Content of Sorghum

Abstract

Nutrient management is an important challenge to agricultural sustainability. In this study, the effects of three nitrogen (N) fertilizer levels (N1 = 0, N2 =150, and N3 = 300 kg ha−1) on growth, chlorophyll content, and antioxidant capacity of two grain sorghum cultivars were investigated in a two-year (2017 and 2018) field trial. The treatments were arranged in a randomized complete block design with three replicates. Nitrogen application (N2 and N3) improved plant growth and antioxidant enzymes activity; compared to the control N1, N increased germination by 18.7%, leaf length by 7.5%, leaf weight by 10.8%, specific leaf weight by 11.6%, and plant height by 2.5% in Siyong 3180 cultivar and increased leaf width by 12.8% and stem weight by 27.4% in CFSH30 cultivar. In 2017 and 2018, increasing nitrogen N2 and N3 enhanced superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activities and leaf protein content in both cultivars. While in 2017, chlorophyll content decreased in the CFSH30 cultivar. Our study showed that increased nitrogen supply could improve morpho-physiological activities of sorghum, but N3 was relatively more effective for sorghum growth in Siyong 3180 cultivar compared to CFSH30 cultivar.