Salinity induced changes in cabbage and their amelioration by K and 5ALA

Abstract

The present research project was carried out to assess the response of salt stress on cabbage (Brassica oleracea L.) plants and recovery through exogenous application of K and 5-ALA at the Institute of Horticultural Sciences, University of Agriculture, Faisalabad, Pakistan. The project consisted of four experiments. The experiment No. 1 was be based on screening of available cabbage varieties against 0, 50, 100, 150 and 200 mM NaCl stress. On the basis of results obtained one salt tolerant and one salt sensitive variety was selected. Two varieties (one salt sensitive and one salt tolerant) selected from the screening experiment were sown in experiment No. 2 plants grown under four salt stress levels (0, 50, 100, 150 and 200 mM NaCl stress), potassium 0 (Control), 5 and 10 mM) levels applied. In the experiment No. 3 plants grown under same salt stress levels and 5-ALA was applied (0 (control), 25, 50, 75 mg/L) solution in the medium. In this way suitable doses of k and 5-ALA was determined, enhancing significant resistance against two cabbage varieties which were exposed to salt stress. In 4th experiment the optimized doses of potassium (10 mM K) and 5-ALA (75 mg/L 5-ALA) were applied on vegetative growth stage (five days after transplanting of nursery) of cabbage plants to determine the effect of K and 5-ALA on different growth characters. Experiments were arranged in CRD with three replications except screening trial which was replicated five times. At the end data collected for different parameters was subjected to statistical analysis by using standard procedures. Beauty ball variety showed salt tolerant while, Green ball showed salt sensitive. More net photosynthetic rate, transpiration rate and stomatal conductance was observed in salt tolerant cultivar (beauty ball) and less net photosynthetic rate was recorded in salt sensitive cultivar (green ball) in all salt stress levels. Maximum leaf water potential, leaf osmotic potential and leaf turgor potential were recorded in both cultivars at 75 mg/L 5-ALA in 200 mM NaCl, and leaf water potential leaf osmotic potential and leaf turgor potential reduced as salt stress levels reduced. Maximum chlorophyll a and b content was recorded in both cultivars at control on optimized dose of potassium and control, as the salt stress level increased more chlorophyll a and b content was recorded in optimized dose 10 mM K, followed by 75 mg/L 5-ALA and control. Minimum catalase and peroxidase activity were recorded in control; as the concentration of salt stress levels increased catalase and peroxidase activity increased in both cultivars. Na+ increased while K+ concentration decreased with increasing salt stress levels. From the above four experiment it is concluded that 10 mM potassium and 75 mg/L 5-ALA should be applied for best results against salinity. While 10 mM K was more economical than 75 mg/L 5-ALA level. Beauty Ball is best suited for cultivation in salt affected areas. Potassium and 5-ALA individually brought about tolerance but the combination of these two may be more helpful combating cabbage under salinity stress.