果树学报2025，Vol.42Issue(10)：2373-2381,9.DOI:10.13925/j.cnki.gsxb.20250345
本砧嫁接对西瓜苗期高温耐性的影响
Effect of wild watermelon rootstock grafting on high temperature toler-ance of watermelon seedlings
摘要
Abstract
[Objective]In order to further explore the effect of rootstock grafting on the high tempera-ture tolerance of watermelon seedlings,this study aims to compare and analyze the growth performance of self-rooted watermelon seedlings and watermelon seedlings grafted on wild watermelon rootstock Ye zhuang No.1 under high temperature stress,reveal the mechanism of grafting technology in improving the high temperature tolerance of watermelon seedlings,and provide scientific basis and technical sup-port for stress-resistant cultivation of watermelon.[Methods]In this study,the self-rooted seedlings of Zaojia watermelon variety was used as a control,and the watermelon rootstock variety Yezhuang No.1 as the rootstock for grafting.The grafted seedlings and self-rooted seedlings were subjected to high tem-perature treatment at 42℃ for 5 days.By measuring and recording the length and thickness of the hypo-cotyl under scion,the relative chlorophyll content and leaf color parameters of cotyledons and true leaves,the photosynthetic fluorescence parameters of true leaves,as well as the content of stress related substances such as malondialdehyde(MDA)and antioxidant enzyme activity such as peroxidase(POD),the effects of grafting on watermelon seedling growth under high temperature stress were com-prehensively evaluated.[Results]Agronomic traits performance:Both high temperature and grafting can significantly increase the thickness of the hypocotyl below the scions,but had little effect on the length of the hypocotyl.Grafted seedlings showed higher relative chlorophyll content(SPAD)between cotyledons and true leaves under high temperature treatment,and the leaf color was more vibrant green,indicating that grafting can alleviate chlorophyll degradation and leaf chlorosis caused by high tempera-ture.In addition,the changes in brightness(L* value),red green value(a* value),and yellow blue value(b*value)of the cotyledons and true leaves on grafted seedlings also showed a positive effect of graft-ing on leaf color.Photosynthetic fluorescence parameters:Under high temperature stress,the actual quantum efficiency(Y(Ⅱ)),photosynthetic electron transfer rate(ETR),and photochemical quenching coefficient(qP)of photosystem Ⅱ(PS Ⅱ)in grafted seedlings were significantly higher than those in self-rooted seedlings,while the non photochemical quenching coefficient(NPQ)was lower.These re-sults indicated that grafted seedlings can maintain higher light energy capture and conversion capacity under high temperature conditions,maintain relatively stable electron transport chain activity,and re-duce the degree of damage to the photosystem.At the same time,although the PS Ⅱ maximum photo-chemical efficiency(Fv/Fm)and potential photochemical efficiency(Fv/Fo)of grafted seedlings de-creased,they were still higher or close to the level of self-rooted seedlings,further verifying the heat tol-erance advantage of grafted seedlings.Physiological indicators related to adversity:In terms of physio-logical indicators related to adversity,grafted seedlings showed higher chlorophyll a,chlorophyll b,and total chlorophyll contents under high temperature stress,as well as lower MDA content and POD activi-ty.These results indicated that grafting can enhance the antioxidant capacity of watermelon seedlings,reduce the degree of membrane lipid peroxidation,and maintain the stability and integrity of cell mem-branes.In addition,although there was no significant difference in soluble sugar content between graft-ed seedlings and self-rooted seedlings under high temperature treatment,grafted seedlings were able to maintain a relatively stable physiological state under high temperature stress.[Conclusion]Grafting en-hanced high-temperature adaptability by coordinating morphology and pigment metabolism:Grafted seedlings exhibited more significant morphological adaptive adjustments under high temperatures,such as a significant increase in hypocotyl thickness,which may be related to auxin mediated cell wall re-modeling.At the same time,grafted seedlings also exhibited advantages in pigment metabolism,such as higher chlorophyll content and more stable leaf color,which helped maintain light capture capacity and photosynthetic electron transfer efficiency.Stability of Photosynthetic Mechanisms and Heat Resis-tant Core Mechanisms Revealed by Fluorescence Parameters:Grafted seedlings can maintain more effi-cient light energy conversion efficiency and relatively stable electron transfer chain activity at high tem-peratures,thanks to the stability of their photosynthetic mechanism.Specifically,higher qP values and lower NPQ values indicated that grafted seedlings can more effectively utilize light energy for photo-chemical reactions and reduce energy loss caused by non photochemical quenching.In addition,the PS Ⅱdamage of grafted seedlings was relatively mild,further demonstrating the heat resistance of their photo-synthetic mechanisms.Membrane system protection and oxidative stress balance:Grafting significantly alleviated the phenomenon of membrane lipid peroxidation induced by high temperature,mainly due to the higher antioxidant capacity and stable chlorophyll content of grafted seedlings.Chlorophyll,as a key pigment in photosynthesis,its stability is crucial for maintaining the integrity of membrane sys-tems.At the same time,the lower POD activity of grafted seedlings also indicated that their basic anti-oxidant capacity was sufficient to eliminate reactive oxygen species(ROS),thereby reducing oxidative stress damage to the membrane system.Physiological integration effect of grafting heat resistance:Compared to cross rootstock grafting,this rootstock grafting may have unique advantages,such as opti-mized material transport,signal transmission fidelity,and integration of circadian rhythms.These advan-tages helped graft seedlings maintain a more stable physiological state and higher growth vitality under high temperature stress.This study indicates that rootstock grafting significantly improves the high-tem-perature tolerance of watermelon seedlings by enhancing hypocotyl stability,maintaining chloroplast pigment homeostasis,optimizing photochemical efficiency and heat dissipation balance,inhibiting membrane lipid peroxidation,and coordinating antioxidant enzyme activity through multiple mecha-nisms.These findings provide important theoretical basis and technical support for the stress-resistant cultivation of watermelons,and have broad application prospects and promotion value.关键词
西瓜/下胚轴/叶片颜色/光合荧光/叶绿素/氧化应激Key words
Watermelon/Hypocotyl/Leaf color/Photosynthetic fluorescence/Chlorophyll/Oxidative stress分类
园艺学与植物营养学引用本文复制引用
邢乃林,严蕾艳,王迎儿,黄芸萍,王毓洪..本砧嫁接对西瓜苗期高温耐性的影响[J].果树学报,2025,42(10):2373-2381,9.基金项目
宁波市科技创新2025重大专项(2021Z006) （2021Z006）
浙江省农业(蔬菜新品种选育)新品种选育重大科技专项(2021C02065) （蔬菜新品种选育）
现代农业产业技术体系(CARS-26) （CARS-26）
