为明确钙在调节网纹甜瓜果实成熟衰老中的生理作用,以网纹甜瓜果实圆片为材料,研究了不同浓度硝酸钙(1,3,5 mmoL/L)处理4,8,12,1,20和24 h情况下,甜瓜果实成熟衰老相关生理指标的变化.结果表明:硝酸钙具有明显延缓甜瓜果实衰老的作用,使果肉硬度显著高于对照,并提高过氧化物酶(POD)、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性,同时降低果肉乙烯释放量、可溶性蛋白含量、外渗电导率的升高速度和脂氧合酶(LDX)活性的作用.但不同处理浓度和处理时间对果实软化的作用效果存在一定差异.与1 mmol/L和3 mmoL/L的硝酸钙相比,5 mmol/L的硝酸钙处理更能显著延缓果实的衰老进程;与处理4 h和8 h相比,处理12 h硝酸钙对以上各成熟衰老指标的促进或抑制作用效果更加显著,但是随着处理时间的延长至处理24 h时,POD、SOD、CAT活性反而下降,对可溶性蛋白的合成、外渗电导率和LOX活性升高速度的抑制效应显著降低.因此,5 mmol/L硝酸钙,并且处理12 h具有较好地减缓网纹甜瓜果实衰老的作用.

Muskmelon discs taken at ripening stage were used by different concentrations of calcium nitrate(1,3,5mmol/L) and various time(4,8,12,16,20,24 h) in order to investigate related to maturation and consenescence physiological parameters.The results showed that calcium nitrate treatment apparently slowed down the consenescence rate,made the flesh firmness higher than the control, elevated the activities of POD, SOD and CAT, retarded the ethylene production,reduced the soluble protein content,and declined the increased speed of electrical conductivity and LOX activity.However,different treat concentrat ions and time had various influences in the maturation and consenescence process of fruit.Moreover,compared with 1 mmol/L and 3 mmol/L, 5 mmol/L treatment more significantly slowed down the maturation and consenescence process of muskmelon.Meanwhile,compared to the calcium nitrate treated for 4 h and 8 h,the discs treated for 12 h were more apparently promoted or inhibited based on above maturation and consenescence physiological parameters;however,with the prolonging of treated time to 24 h, the activities of POD,SOD and CAT dropped markedly,as well as the inhibition of synthesis of soluble protein,and the increased speed of electrical conductivity and LOX activity were reduced markedly.Therefore,5mmol/ L calcium nitrate and treated for 12 h could delayed the maturat ion and consenescence process of muskmelon.