Syazrul Iqmal, J1*., Nurhazwani, M1., Rosnani, A. G2., Nurul Afza, K2., Mohd Hazrul, Z. T1. and Ahmad Ariff Luqman, A. H1.
Abstract
Sorghum is a globally significant cereal crop known for its resilience to abiotic stress, making it well-suited for cultivation in marginal environments such as Beach Ridges Interspersed with Swales (BRIS) soil. However, the effects of nitrogen application on its physiological performance in such conditions remain underexplored. This study evaluates the physiological responses of two inbred sorghum genotypes, V1 (India) and V2 (Brachy Sorgho), under three nitrogen application rates: 0 g N/plant (control), 2 g N/plant, and 4 g N/plant, applied at 30 days after sowing (DAS). The experiment followed a factorial 2 × 3 arrangement in a Randomised Complete Block Design (RCBD) with four replications, and the data were analysed using two-way analysis of variance (ANOVA). Key physiological parameters measured included photosynthetic rate, transpiration rate, stomatal conductance, stomatal density, photosynthetic pigments and leaf colour. While nitrogen application did not significantly affect photosynthetic or transpiration rates (p >0.05), possibly due to environmental limitations such as low water holding capacity and soil nutrient retention in BRIS soils, stomatal conductance, stomatal density, pigment concentration, and leaf colour improved significantly (p <0.05) under 2 g N/plant and 4 g N/plant applications. Notably, applying 2 g N/plant nitrogen at 30 DAS optimised physiological responses, resulting in higher grain yield both in terms of panicle grain weight and grain weight/panicle. This application rate also proved most cost-effective, minimising fertiliser input while maintaining productivity. These findings highlight the importance of precise nitrogen management to improve sorghum performance in BRIS soils.
Keywords: sorghum, physiological response, nitrogen level, photosynthesis efficiency, chlorophyll synthesis
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