A Review on Nutritional Significance of Sulfur in Pulse Crops

Abstract

Sulfur (S) is an important secondary plant nutrient required for plant growth and is particularly important in leguminous crops due to its role in amino acid synthesis, protein formation, enzyme activity and biological nitrogen fixation. A significant proportion of agricultural soils in Asia, including over 40% in India, are deficient in available sulfur. This widespread deficiency has adversely affected crop yield, nitrogen use efficiency and seed quality in pulse crops, especially under semi-arid tropical conditions. This study aims to evaluate the role and requirement of sulfur nutrition in pulse crops with specific emphasis on its influence on growth, nodulation, yield attributes and seed quality. The study focuses on sulfur availability in soils, sulfur uptake by pulse crops in the sulphate (SO₄²⁻) form through roots and its subsequent translocation to developing seeds. Comparative sulfur requirements of major pulse crops such as black gram, soybean and mung bean were analyzed under different agro-climatic conditions. Observations on physiological, biochemical and yield-related parameters were used to assess sulfur deficiency and sufficiency effects. Sulfur was found to be critical for the biosynthesis of sulfur-containing amino acids, proteins, vitamins and protective metabolites such as glutathione. Adequate sulfur supply significantly improved nodulation, nitrogen fixation, photosynthesis, protein content and overall productivity of pulse crops. Mung bean required higher sulfur (45 kg ha⁻¹) compared to black gram and soybean (40 kg ha⁻¹). Sulfur deficiency led to chlorosis, stunted growth, reduced flowering, poor pod and seed development, lower protein synthesis and increased susceptibility to biotic and abiotic stresses. Sulfur nutrition plays a vital role in sustaining growth, yield and quality of pulse crops, particularly in sulfur-deficient soils of semi-arid tropical regions. Regular sulfur replenishment through appropriate fertilizer and organic sources is essential for improving crop productivity, enhancing nitrogen use efficiency and ensuring sustainable pulse production.