Effects of Pretreatment with Salicylic Acid on Growth and Nutrient Uptake of Sesame Seedlings under Salt Stress

Salinity stress is regarded as one of the most important abiotic factors limiting plant growth and agricultural products, particularly in arid and semi-arid regions. Sesame (Sesamum indicum L.) is an important oilseed crop rated moderately salt tolerant and capable of producing profitable crops in saline conditions. Germination and seedling establishment are critical stages in the life cycle of plants especially under stress conditions. Different methodologies have been adopted by plant physiologists in different crops to alleviate salt stress. Seed priming has proven beneficial in this regard in many important agricultural crops. Salicylic acid is one of the physiological processes regulators that it increases resistant of plants to environmental stresses such as salinity stress.
To evaluate the effect of different levels of salinity and seed pretreatment with salicylic acid (SA), on some growth indices and nutrient uptake of sesame (Sesamum indicum L.) seedling, a factorial experiment with completely randomized design and four replicates was conducted in Department of Agronomy, Rafsanjan University of Vali-e- Asr. Factors were seed pretreatment with three levels including, distilled water, 1 mM salicylic acid and 2.5 Mm salicylic acid and salinity at three levels: control (Hoagland standard solution, 2.5 dS.m-1), 6 and 9 dS.m-1. A dry seed treatment (no pretreatment) was also added and considered as control.
Results showed that at 9 dS/m-1both SA concentrations caused significant increase in emergence percentage compared to dry seed and distilled water. Plant leaf area and SPAD values decreased along with salinity in dry seed and distilled water, nevertheless, at 2.5 mM SA, values were not significantly different between 6 and 9 dS.m-1. On the other hand, SA seed pretreatment decreased shoot Na and increased K content, although shoot Mg and P contents were the highest at 1 and 2.5 mM SA, respectively. The effects of SA pretreatment on shoot dry mass was not clear. The highest shoot, root and seedling dry weights were observed at control salinity in dry seed, distilled water and 2.5 mM SA and decreased with salinity level. Seedling dry weight was not significantly lower than control only in 1 mM SA and 9 dS.m-1 salinity.
Generally, in this experiment ameliorative effects of SA pretreatment were more pronounced on seedling survival and some nutrient uptake.