【作者】 白如意； 宋希梅； 沈健； 贾蓝溪； 程永安； 马建祥； 张显； GUO Yanliang； LI Shiyu； ZHANG Yong；

【Author】 BAI Ruyi;SONG Ximei;SHEN Jian;JIA Lanxi;GUO Yanliang;LI Shiyu;CHENG Yongan;MA Jianxiang;ZHANG Yong;ZHANG Xian;College of Horticulture,Northwest A&F University;

【机构】 西北农林科技大学园艺学院； College of Horticulture,Northwest A&F University；

【摘要】 以南瓜品种‘永安2号’幼苗为试验材料,采用室内盆栽实验,在叶面喷施不同浓度(0、50、100、150、200、300μmol·L^-1)褪黑素（MT）后进行低温（10℃/7℃）胁迫处理,考察幼苗生长指标以及相对电导率、抗氧化酶活性、渗透调节物质含量等抗逆生理指标的变化,初步探讨外源褪黑素缓解南瓜幼苗低温冷害的生理机制。结果表明:在低温胁迫条件下,南瓜幼苗出现叶片萎蔫失水、边缘失绿褪色、向内卷曲等冷害症状;幼苗株高、茎粗、鲜重、干重和壮苗指数等生长指标及叶片相对叶绿素含量均显著降低;叶片相对电导率、MDA含量和O₂^·-产生速率显著升高50%以上,超氧化物歧化酶、过氧化物酶、过氧化氢酶、抗坏血酸过氧化物酶、谷胱甘肽还原酶、脱氢抗坏血酸还原酶活性以及可溶性糖、可溶性蛋白和脯氨酸含量也大多显著升高。与低温胁迫处理相比较,叶面喷施不同浓度褪黑素后,南瓜幼苗叶片冷害症状均得到不同程度恢复,并以100μmol·L^-1 MT处理生长状态最好,植株形态表型与对照已没有明显差异;幼苗生长指标以及叶片相对叶绿素含量、6种抗氧化酶活性、3种渗透调节物质含量均不同程度提高,并随着MT浓度升高均先升后降,且均在100μmol·L^-1 MT处理最高。研究发现,外源褪黑素能通过提高叶片叶绿素含量、增强抗氧化酶活性、增加渗透调节物质积累,显著降低低温冷害造成的膜质过氧化程度,有效减轻低温胁迫对南瓜幼苗的伤害,增强其抵抗低温能力,恢复幼苗的正常生长,且喷施浓度为100μmol·L^-1效果最佳。更多还原

【Abstract】 With the pumpkin variety ’Yong an No.2’ seedlings as the tested material,we adopted the indoor pot experiment,sprayed different concentrations(0,50,100,150,200,300 μmol·L^-1) of melatonin（MT）,and then carried out low temperature（10 ℃/7 ℃） stress treatment,to investigate the changes of seedling growth index,relative electric conductivity,antioxidant enzyme activity,osmoregulation substance content and other physiological indexes of stress resistance,and preliminarily explore the physiological mechanism of exogenous melatonin alleviating chilling injury of pumpkin seedlings.The results showed that under cold stress,pumpkin seedlings showed symptoms of chilling injury such as leaf wilting,water loss,edge chlorosis and discoloration,inward curling,etc,the growth indexes such as plant height,stem diameter,fresh weight,dry weight and strong seedling index and the relative chlorophyll content of leaves were significantly decreased,the relative electric conductivity,MDA content and O₂^·- production rate of leaves were significantly increased by more than 50%,and the activities of superoxide dismutase,peroxidase,catalase,ascorbic acid peroxidase,glutathione reductase,dehydroascorbic acid reductase,soluble sugar,soluble protein and proline were also significantly increased.Compared with the cold stress treatment,the chilling injury symptoms of pumpkin seedling leaves were recovered to different degrees after spraying different concentrations of melatonin on the leaves,and the growth state of 100 μmol·L^-1 MT treatment was the best,and there was no significant difference between the plant morphology and phenotype and the control;the seedling growth index,the relative chlorophyll content of leaves,the activities of six antioxidant enzymes,and the contents of three osmoregulatory substances all increased to varying degrees,and all increased first and then decreased with the increase of MT concentration,and all were the highest under 100 μmol·L^-1 MT treatment.The study found that exogenous melatonin can increase the chlorophyll content of leaves,enhance the activity of antioxidant enzymes,increase the accumulation of osmoregulation substances,significantly reduce the degree of membrane peroxidation caused by low temperature chilling injury,effectively reduce the damage of cold stress on pumpkin seedlings,enhance their ability to resist low temperature,and restore the normal growth of seedlings,and the spraying concentration of 100μmol·L^-1 has the best effect.更多还原