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.