黄瓜实生苗与嫁接苗生长发育及光合荧光特性对自毒胁迫的响应差异

Different response of growth,development and photosynthetic fluorescence characteristics of non-grafted and rootstock grafted cucumber seedling to autotoxic stress

采用水培方式,以黄瓜嫁接苗与实生苗为试材,外源肉桂酸(CA)模拟自毒胁迫,分别从幼苗的生长发育、根系形态和光合荧光特性等方面,对比研究以黑籽南瓜为砧木的嫁接苗与黄瓜实生苗对自毒胁迫响应差异的生理机制。结果表明,第6天时,CA胁迫下黄瓜实生苗(NG-T)的株高和叶面积比对照(NG-CK)分别降低了32.96%和33.41%,而嫁接苗的株高、茎粗、叶面积受抑制程度轻,且长势明显优于实生苗;0.5 mmol·L^-1CA对黄瓜嫁接苗的根长和根尖数的抑制率为6.95%和7.30%,仅为黄瓜实生苗的18.66%和16.37%;CA胁迫下,嫁接能够稳定维持黄瓜幼苗体内的叶绿素含量;嫁接苗的蒸腾速率(Tr)、净光合速率(Pn)、气孔导度(Gs)、Fv/Fm、Fv/Fo和非光化学淬灭(NPQ)均高于实生苗,分别高出10.87%、156.86%、78.33%、5.58%、17.59%和38.07%。说明嫁接可促进黄瓜植株的生长,减轻自毒物质对光合系统的损伤,从而提高对自毒胁迫的耐受性。

In the experiment,hydroponics was used to study the difference physiological mechanism of the non-grafted and rootstock grafted cucumber seedling in response to autotoxic stress,using exogenous cinnamic acid(CA)to simulate autotoxic stress.The growth and development of seedlings,root morphology and photosynthetic fluorescence characteristics were compared between non-grafted and rootstock grafted cucumber.The results showed that on day 6(d),plant height and leaf area of non-grafted cucumber seedlings(NG-T)under cinnamic acid stress were 32.96%and 33.41%lower than those of control(NG-CK),while plant height,stem diameter and leaf areas of rootstock grafted seedlings were slightly inhibited,and growth vigor was significantly better than that of non-grafted seedlings.The inhibition rates of root length and root tip number of grafted seedlings under 0.5 mmol L^-1 CA treatment were 6.95%and 7.30%,respectively,only 18.66%and 16.37%of the non-grafted cucumber seedlings,which indicated the resistance of grafted seedlings to CA stress was stronger.Under CA stress,grafting could keep the chlorophyll content of cucumber seedlings stable.The transpiration rate(Tr),net photosynthetic rate(Pn),stomatal conductance(Gs),Fv/Fm,Fv/Fo and non-photochemical quenching(NPQ)of grafted seedlings were increased than those of non-grafted seedlings by 10.87%,156.86%,78.33%,5.58%,17.59%and 38.07%,respectively.The results showed that grafting could promote the growth of cucumber plants,inhibit the damage of photosynthetic system caused by autotoxic substances,and improve the tolerance to autotoxic stress.