Comparative analysis of root system architecture and sulfur acquisition among chickpea cultivars under contrasting sulfur nutrition in hydroponic cultures

Sulfur (S) is an essential element for plant growth, development and defense against biotic and abiotic stresses. Sulfate assimilation in plants is demand-driven and low soil S severely impairs growth and reduces seed protein quality. Like many legumes, chickpea (Cicer arietinum L.) seeds are characterized by suboptimal levels of cysteine and methionine. Therefore, it is imperative to screen the cultivars for maximum sulfate assimilation and utilization efficiency. In the present study, we screened a total of sixteen chickpea cultivars based on root system architecture (RSA) under contrasting S regimes-S-starvation and S-sufficient conditions-highlighting the potential correlations between altered root plasticity, corresponding dry mass and S allocation within plants at the whole-plant level. The root morphological traits were measured and the values of RSA traits for Desi cultivars (PUSA256, PUSA547, PUSA5028 and PUSA362) and Kabuli cultivars (PUSA1003 and PUSA1053) were significantly higher even under S-starvation conditions, maximizing the concurrent increase in sulfur acquisition, indicating their sulfur efficiency. However, the fold decrease of these traits, dry mass and sulfur content at S-starvation was higher for Kabuli cultivars, coinciding with plant chlorosis, indicating their susceptibility to S-starvation stress. Additionally, cultivars such as PUSA3022, KAK2, PUSA5023, BGD112 and BGD72 displayed drastic declines in root traits and sulfur content under S-starvation, highlighting their limited capacity to adapt via root plasticity, particularly in lateral root development. These findings emphasize the importance of root morphogenetic traits in sulfur efficiency and provide a basis for breeding chickpea cultivars with improved nutrient use efficiency.