咖啡根系分泌物对嫁接后植株生长及叶片保护酶活性的影响

Effects of root exudates on the growth and activities of leaf protective enzymes of grafted coffee plants

咖啡根系分泌物引起的自毒作用是造成咖啡连作障碍的主要原因,而种间嫁接是抑制咖啡自毒的有效方式。为探明嫁接抑制自毒机制,采用盆栽试验研究咖啡主栽品种根系分泌物对嫁接植株的化感效应。结果表明:根系分泌物抑制了咖啡自根苗生长,且随着根系分泌物浓度升高,抑制作用增强;低浓度根系分泌物能促进咖啡嫁接苗生长,经根系分泌物处理后的嫁接苗株高、根长、地上部干重和根干重分别较未处理的对照嫁接苗平均增加了22.15%、6.52%、44.80%和20.67%,根系活力、叶片保护酶活性也明显增加;高浓度根系分泌物虽未能促进嫁接苗生长,但嫁接苗较自根苗生长优势显著,经根系分泌物处理后嫁接苗POD、CAT和SOD活性分别较自根苗增加了60.61%、27.27%和18.24%,MDA含量显著减少,根系活力显著增加。因此,在根系分泌物处理下,嫁接苗能通过提高自身保护酶活性等方式,促进植株生长或使植株生长所受抑制减少。

Autotoxicity of root exudates is a main reason of coffee continuous cropping obstacle, and grafting is considered as an effective way of alleviating autotoxicity. To clarify the autotoxicity-inhibition mechanism of grafting, the allelopathy effect of root exudates of cultivated varieties on grafted plants was measured using a pot experiment. The results showed that the growth of own-rooted coffee was inhibited by root exudates, and the inhibition was strengthened with the increased concentration of root exudates. The growth of grafted coffee was promoted by low concentration of root exudates. The plant height, root length, shoot dry weight and root dry weight of grafted coffee were increased by 22.15%, 6.52%, 44.80% and 20.67% respectively. The root activity and leaf protective enzyme activities were significantly increased. The growth of grafted coffee was not improved by high concentration of root exudates, but still the grafted coffee could grow better compared with the own-rooted coffee; the POD activity, CAT activity and SOD activity were increased by 60.61%, 27.27% and 18.24% respectively. The root activity was significantly increased, and MDA content was significantly decreased. In conclusion, under the treatment of root exudates, some factors such as the leaf protective enzyme activities were increased by grafting, and the growth inhibition was reduced or even the growth was promoted.