Studies On Effects Of Various Rootstocks On The Yield And The Resistant Mechanism Of Tomato To Bacterial Wilt

In this experiment four types of grafted tomato seedlings were obtainedthrough Zhenmu No. 1 (Lycopersicon esculentum Mill.) and Guizhen No. 1(Lycopersicon esculentum Mill.) as two rootstocks and Zhenhong andDamingxing as two scions. The effects of various rootstocks onphysiological and biochemical characteristics and resistant mechanism oftomato to bacterial wilt were studied. Through investigating of under fieldconditions, determinating of physiological and biochemical characteristics,analyzing of fruit quality and testing of physiological indexes of resistanceto tomato bacterial wilt, the results were as follows:(1) There were high affinity between two rootstocks and scion, all thesurvival rates of grafted tomatoes were above 81.2%. The survival rates ofgrafted Zhenmu No. 1 were lower than that of Guizhen No. 1.(2) Yields were increased after tomatoes were grafted. The growth ofgrafted tomatoes was better than that of control. Various rootstocks had verypositive significant influence on tomato yield compared with the control.(3) There were not obviously negative effects of various rootstocks onexternal quality of tomatoes. Internal quality of tomatoes was better thanthat of control. Taste and flavor between various rootstocks-graftedtomatoes and the control were the same.(4) The photosynthetic characteristics of grafted tomatoes(Zhenghong/Zhenmu No. 1, Zhenghong/Guizhen No. 1) and own root tomato (Zhenghong) under field conditions were systematically studied byusing the LI-6400 portable photosynthesis system. The results were asfollows: The light saturation points of own root tomatoes were significantlyhigher than that of grafted tomatoes. The significant differences of lightcompensation point between own root tomatoes and grafted tomatoes werenot found. The CO₂ compensation points of grafted tomatoes weresignificantly lower than that of own root tomatoes. The apparent quantumefficiency was between 0.062 and 0.073. Under suitable temperature andsaturation light intensity condition, CO₂ saturation point ranged from844μmolCO₂.mol^-1 to 971μmolCO₂.mol^-1, and the carboxying efficiencywas between 0.055～0.086 molCO₂.m².S^-1. The CO₂ compensation point ofthe Zhenghong, Zhenghong/Rootstockl, Zhenghong/Rootstockllscion/stock) were 74.0μmolCO₂.mol^-1, 60.8μmol CO₂.mol^-1, 50μmolCO₂.mol^-1 respectively. The photosynthetic diurnal variations in leaves oftomato had been studied. The diurnal variations of net photosynthetic ratesand respiration rates exhibited "single peaked pattern". They had the highestpoint at midday and existed no "midday depression" in thephotosynthesis. The diurnal variations of internal CO₂ concentration werejust opposite to net photosynthetic rates.(5) There were changes in the isozyme spectra of POD, SOD and PPOafter grafted by various rootstocks. The isozyme spectra of POD and PPO ingrafted tomatoes by the resistant rootstock (Guizhen No. 1) were more thantwo scions. There were no changes at isozyme spectra numbers of SOD inleaves of tomatoes.(6) Under tomato bacterial wilt stress, the sequence of disease-resistancewas Damingxing/Guizhen No.1＞Damingxing/Zhenmu No.1＞Damingxing, Zhenhong/Guizhen No.1＞Zhenhong/Zhenmu No.1＞ Zhenhong. There was a negative correlation trend between electricconductivity percentage, content of MDA and disease-resistance. There wasa positive correlation trend between activities of POD, SOD, PPO anddisease-resistance.To sum up, Guizhen NO. 1 was the best rootstock of scion. Comparedwith control, the total yield was increased above 106.0%, and preventioneffectiveness was above 88.1%.