常温和低温条件下不同浓度外源褪黑素对降香黄檀幼苗的生理生态影响

Effects of different exogenous melatonin concentrations on eco-physiological characteristics of Dalbergia odorifera seedlings under ambient and low temperatures

为探究外源褪黑素对不同温度下降香黄檀幼苗的生理生态影响,该研究开展了不同浓度外源褪黑素(300、500、600、700、900、1200μmol·L^(-1))对常温(白天28℃/夜晚25℃)和低温(白天8℃/夜晚5℃)下降香黄檀(Dalbergia odorifera)幼苗的生长发育、光合作用、叶片色素含量、叶片水分状况、膜系统等方面影响研究,并通过隶属函数分析综合评价筛选出具有促进降香黄檀幼苗生长发育和提高低温耐受性的最适外源褪黑素浓度。结果表明:(1)在常温下喷施各个浓度的褪黑素溶液,在生长发育(形态、茎高增长和株高增长),光合作用参数[净光合速率(P_(n))、气孔导度(G_(s))、胞间二氧化碳浓度(C_(i))和蒸腾速率(T_(r))],光合色素[总叶绿素(Total Chl)、叶绿素a(Chl a)、叶绿素b(Chl b)和类胡萝卜素(Caro)]和可溶性蛋白含量上均有一定的提高。(2)低温胁迫处理下,喷施各个浓度的褪黑素溶液可在不同程度上缓解低温胁迫对植株形态、茎高增长、株高增长、P_(n)、C_(i)、T_(r)、Total Chl、Chl a、Caro、露点水势(DWP)、相对电导率(RC)、丙二醛(MDA)和可溶性蛋白含量等方面的负面影响。(3)隶属函数分析表明,600~700μmol·L^(-1)外源褪黑素处理促进降香黄檀幼苗生长和缓解低温冷害效果最佳。该研究结果为提高降香黄檀幼苗的低温耐受能力提供了科学依据,有利于降香黄檀在亚热带低温地区的栽培管理。

The purpose of this study was to explore the eco-physiological effects of different exogenous melatonin concentrations on the Dalbergia odorifera seedlings under different temperatures.The effects of different exogenous melatonin concentrations(300,500,600,700,900,1200μmol·L^(-1))on the eco-physiological traits in term of plant growth,photosynthesis,leaf pigment content,leaf water status,membrane system in D.odorifera seedlings under ambient temperature(28℃day/25℃night)and low temperature(8℃day/5℃night)were studied.The optimum concentration of melatonin,which could promote the growth and development and enhance the low temperature tolerance,was screened out through the comprehensive evaluation of subordinate function analysis.The results were as follows:(1)Application of all exogenous melatonin concentrations could increase the growth and development of D.odorifera(morphology,stem height and plant height),the photosynthetic parameters(P_(n),G_(s),C_(i),and T_(r)),the pigment contents(Total Chl,Chl a,Chl b,and Caro),and soluble protein content under ambient temperature.(2)Under low temperature stress,spraying different concentrations of melatonin solution could alleviate the negative impacts caused by low temperature on morphology,stem height increment and plant height increment,P_(n),C_(i),T_(r),Chl,Chl a,Caro,dew point water potential(DWP)and relative conductivity,malonaldehyde and soluble protein contents.(3)The results of subordinate function analysis showed that 600-700μmol·L^(-1)melatonin had the best effects on promoting growth and development and alleviating chilling damages.This study provides scientific guidance for coping with chilling stress on D.odorifera seedlings and popularizing its cultivation in low temperature regions of subtropical areas.