Effect of salicylic acid on growth, nodulation and N2-fixation in water stressed chickpeas using 15N and 13C

Abstract

A pot experiment was conducted to determine the impact of foliar spraying of salicylic acid (SA) on dry matter (DM), carbon isotope discrimination (Δ¹³C), nitrogen uptake (NY) and N₂-fixation (using ¹⁵N) by chickpea plants subjected to three soil moisture regimes (high stress FC1, mild stress FC2 and well-watered FC3). Water stress drastically affected nodulation, DM, NY, N₂-fixation. However, plants responded positively to SA as a means of enhancing growth and overcoming the stress conditions, particularly under FC2 where the measured growth criteria (DM and NY) were relatively similar to those of the FC3. Salicylic acid significantly enhanced amounts of fixed N₂ by 32, 30 and 19% in FC1, FC2 and FC3, respectively. Water stress caused a decrease in Δ¹³C values. However, SA increased Δ¹³C in water stress treatments, implying that a maximization of DM may occur via an enhancement of CO₂ uptake due to stomatal opening and carboxylation activity. In conclusion, the beneficial effect of SA in enhancing plant performance (growth, N-uptake and N₂-fixation) was affected by soil water content. SA application may be considered an important agricultural practice for the better symbiotic performance in water stressed as well as in well watered chickpeas plants.