Insights on the Adaptation of the Tunisian Halophyte Sulla carnosa to Fe Deficiency Alone and in Combination with Salicylic Acid Seed Priming

Improving forage crops performance under iron (Fe) deficiency conditions is challenging, thus besides genotypic screening new approaches are required. Among these new approaches, priming technique is eco-friendly, efficient and cost effective. The aim of this study was to evaluate the remedial effect of salicylic acid (SA 0.25 mM) seed priming on plant growth, ionic content, in addition to the photosynthetic capacity under different Fe concentration conditions in two Sulla carnosa cultivars ‘Sidi Khlif’ and ‘Kalbia’, with different tolerance to such constraint. Under unprimed conditions, Fe deficiency reduced shoot relative growth rate (RGR), Fe and potassium (K) contents along with chlorophyll concentration in both cultivars, compared to the control. Nevertheless, S. carnosa was able to maintain root RGR under these unfavorable conditions. Additionally, Fe deficiency affected differently the gas exchange parameters. Interestingly, priming seeds with SA improved growth performance, as well as Fe and K uptake of deficient S. carnosa plants via simulating the medium acidification. The changes above described in all physiological parameters were much less pronounced in ‘Sidi Khlif’ than in ‘Kalbia’. We conclude that SA seed priming had a positive effect on the physiological behavior of S. carnosa plants subjected to Fe deficiency. However, the degree of recover varied depending on the cultivar and the plant tissue. Mitigation of Fe deficiency by SA could be in part due to the aptitude to assure an enhanced plant growth and the adjustment of photosynthetic activity promoting more effective nutrient assimilation.