The effect of NaCl seed priming on salt tolerance, antioxidant enzyme activity, proline and carbohydrate accumulation of Muskmelon (Cucumis melo L.) under saline condition

Abstract

Seeds of Muskmelon (Cucumis melo L.) cultivars' Garmsar (local cultivar in south of Iran) and Flexuosus were primed with 100 mmol NaCl solution for 36 h at 20°C. In experiment 1, after priming four replicates of 25 seeds were germinated between two rolled sheets of filter paper with 10 ml of respective salinity test solutions. Seeds were allowed to germinate at 22 ± 1°C in the 16/8 dark and light for 12 days. The experimental design was two factors factorial arranged in a completely randomized design (CRD), with four replications. The first factor was salinity stress (0, 50, 100 and 150 mmol NaCl solution) and the second factor was NaCl Primied (P) and nonprimed seeds (NP). Results indicated that salt stress decreased seed germination and seedling dry weight of muskmelon cultivars but seed priming increased seed germination and seedling growth. At 150 mmol NaCl solution, highest seedling dry weight obtained from cv. Garmsar. In experiment 2, after priming, P and NP muskmelon seeds were sown in germination boxes filled with perlit and sphangnum peat (3:1). 5 seeds sown in any pot and the germination boxes were placed in greenhouse where temperature ranges between 16/26°C, night/day for 3 weeks. The experimental design was two factors factorial, arranged in a completely randomized block design, with four replications. The factors were like experiment 1. Results revealed that salt stress decrease shoot dry weight of muskmelon cultivars, but shoot dry weight of P seeds were higher compare to NP seeds. Seed priming increased antioxidant enzyme activity, soluble carbohydrate and proline content and decrease seed membrane damage of muskmelon cultivars because MDA concentration was low in P group in contrast to NP group. Under 150 mmol salinity level, highest shoot dry weight, antioxidant activity, carbohydrate accumulation and lowest MDA concentration obtained in cv. Garmsar at P group. Key words: Antioxidant enzyme, muskmelon, osmotic adjustment, priming.