Assessment of Morphological and Biochemical Response of Different Onion Cultivars Under Salt Stress Conditions

Abstract


 
 
 Salinity is among the major abiotic challenges that limit soil’s ability to supply nutrients to the plants which is detrimental to crop optimum productivity. Onion is globally an important vegetable crop that is affected by salt stress. Present study is focused on the impact of salinity on growth, production and quality of different onion cultivars. Ten onion cultivars were tested against three salinity levels i.e. 40, 80 and 120 mM NaCl during the year 2017-18. A completely randomized design (CRD) having four replications was used for analyzing the results statistically. The results pertaining to the days of germination indicated that the cv. Red Nasik took the minimum days (5.46) to attain 50% germination as compared to cv. Robinia (14.0). High salt concentration increased the time for germination and took maximum days (11.27) for 50% germination in120 mM NaCl salt level with highest plant mortality (14.06%) in cv. Faisal Red. Similarly, maximum germination (95.62%) was recorded in onion cv. Red Nasik. In the control, germination was 84.63% while the higher salt concentrations (120 mM NaCl) resulted in the minimum seed germination (61%). Plant height, the number of leaves and chlorophyll contents decreased with rising salinity levels. Similarly, chlorophyll contents decreased with each additional increased in salt concentration and the maximum value for this trait was recorded in control as compared to the minimum in 120 mM NaCl i.e. 58.42 SPAD. However, maximum proline contents (30.87 μ mol g-1) were recorded in 120 mM NaCl as compared to the minimum (9.86 μ mol g-1) at control. Similarly, TSS improved with increasing salinity and the minimum TTS (13.00 °Brix) were recorded in control as compared to the maximum in 120 mM NaCl) i.e. 16.98 °Brix.