外源褪黑素对桃生长及果实品质的影响

【目的】探讨外源褪黑素对桃生长和果实品质的影响。【方法】以早熟桃‘早蜜’为试材,于果实膨大期对其叶片喷施不同浓度的褪黑素,测定了桃果实成熟期的新梢生长量、生理状况和果实品质指标。【结果】50~150μmol·L^-1的褪黑素处理能促进桃新梢的生长,增加其茎长和茎粗。150μmol·L^-1褪黑素提高了桃叶片超氧化物歧化酶活性,但其余处理较对照有所降低;50~100μmol·L^-1褪黑素提高了桃叶片过氧化氢酶活性,其余处理较对照有所降低。褪黑素提高了桃果实的苯丙氨酸解氨酶、抗坏血酸过氧化酶和脂氧合酶活性,降低了多酚氧化酶活性。100~150μmol·L^-1褪黑素增加了桃果实单果质量、果实纵横径,降低了果实硬度,提高了果实维生素C、可溶性固形物、蔗糖、果糖和山梨醇含量,降低了葡萄糖含量。【结论】褪黑素能够促进桃生长、改善桃果实品质。

Effects of exogenous melatonin on growth and fruit quality of peach(Prunus persica)

【Objective】The object of this study was to investigate the effects of exogenous melatonin(MT)on the growth and fruit quality of peach(Prunus persica).【Methods】The early ripe peach‘(Zaomi’)was used as the materials,and different concentrations of MT were sprayed on the leaves of peach during the fruit expansion period.The new branches growth(stem length and stem diameter),photosynthetic physiologyphotosynthetic pigment content(chlorophyll a,chlorophyll b,total chlorophyll,and carotenoid),antioxidant enzyme(superoxide dismutase and catalase)activity,osmotic substance content(malondialdehyde and soluble protein)]and fruit qualityrelated metabolic enzyme(phenylalanine ammonia lyase,ascorbate peroxidase,lipoxygenase,and polyphenol oxidase)activity,appearance quality(single fruit weight,fruit longitudinal diameter,fruit diameter,fruit firmness and fruit shape index),internal solution(vitamin C,soluble solids and titratable acid)content and different sugar component(total sugar,sucrose,fructose,sorbitol and glucose)content]of peach were determined during the mature period.【Results】50-150μmol·L^-1 MT treatment promoted the new shoot growth of peach by increasing the stem length and stem diameter,while 200μmol·L^-1 MT treatment decreased the new shoot growth.The different concentrations of MT had different effects on the contents of chlorophyll a,chlorophyll b,total chlorophyll,and carotenoid in peach leaves.The concentrations of 100 and 150μmol·L^-1 MT enhanced the chlorophyll a/b of peach leaves,while the concentrations of 50 and 200μmol·L^-1 MT reduced or had no significant effect on the chlorophyll a/b.When the MT concentration was 150μmol·L^-1,the superoxide dismutase activity of peach leaves enhanced,however the other MT concentrations reduced that compared with the control.The concentrations of 50-100μmol·L^-1 MT enhanced the catalase activity of peach leaves,the other treatments reduced the catalase activities.The concentration of 50μmol·L^-1 MT also increased the contents of malondialdehyde and soluble protein in peach leaves,and 100,150,and 200μmol·L^-1 MT decreased these two osmotic substances contents.Different MT concentrations enhanced the phenylalanine ammonia lyase,ascorbate peroxidase and lipoxygenase activities of peach fruits,and reduced the polyphenol oxidase activity.The order of the effects of MT on the phenylalanine ammonia lyase activity was 200μmol·L^-1>150μmol·L^-1>50μmol·L^-1>100μmol·L^-1>0μmol·L^-1,on the ascorbate peroxidase activity was 150μmol·L^-1>100μmol·L^-1>50μmol·L^-1>200μmol·L^-1>0μmol·L^-1,on the lipoxygenase activity was 150μmol·L^-1>100μmol·L^-1>50μmol·L^-1>200μmol·L^-1>0μmol·L^-1,and on the polyphenol oxidase activity was 0μmol·L^-1>200μmol·L^-1>100μmol·L^-1>150μmol·L^-1>50μmol·L^-1.The concentrations of 100 and 150μmol·L^-1 MT increased the single fruit weight of peach fruits by 13.57%and 14.62%,respectively,compared with the control,and the concentrations of 50 and 200μmol·L^-1 MT decreased the single fruit weight.The concentrations of 100 and 150μmol·L^-1 MT increased the longitudinal diameter and diameter of peach fruits and decreased the fruit firmness,while the concentrations of 50 and 200μmol·L^-1 MT decreased fruit longitudinal diameter and transverse diameter and increased the fruit firmness.There were no significant differences of fruit shape index among the fruits treated with different MT concentrations.The concentrations of 100 and 150μmol·L^-1 MT increased the contents of Vitamin C and soluble solids in peach fruit,while the concentrations of 50 and 200μmol·L^-1 MT decreased or had no significant effects on these items.The concentrations of 100 and 150μmol·L^-1 MT increased the Vitamin C content by 31.40%and 19.69%,respectively,and increased the soluble solids content by 18.83%and 21.37%,respectively,compared with their respective control.The concentrations of 50 and 200μmol·L^-1 MT decreased the content of titratable acid in peach fruit by 25.28%and 19.06%,respectively,while other concentrations of MT had no significant effects on the content of titratable acid.The concentrations of 50,100 and 200μmol·L^-1 MT decreased the total sugar content in peach fruits,and 150μmol·L^-1 MT had no significant effects.The concentrations of 100 and 150μmol·L^-1 MT increased the sucrose content in peach fruits by 10.11%and 17.04%,respectivel and other treatments decreased the sucrose content.With the increase of MT concentration,the fructose content in peach fruit increased when the MT concentration was not higher than 100μmol·L^-1,and decreased when the MT concentration was higher than 100μmol·L^-1,with the maximum at 100μmol·L^-1 MT(increased by 21.37%compared with the control).100μmol·L^-1 MT increased the sorbitol content in peach fruits by 24.11%.The concentrations of 100 and 150μmol·L^-1 MT decreased the glucose content in peach fruits by 37.25%and 26.16%,respectively,and other treatments increased the glucose content.【Conclusion】MT could promote the shoot growth of peach by improving the resistance,increase the yield of peach by increasing the single fruit weight,and improve fruit quality of peach fruits by improving the sugar component content.