柑橘黄龙病菌对沙田柚田间性状和果实品质的影响

【目的】明确柑橘黄龙病菌对沙田柚Citrus maxima (Burm.) Merr. cv. Shatian Yu田间性状和果实品质的影响。【方法】结合田间调查和室内试验系统研究沙田柚感染黄龙病菌后叶片症状、果实内外品质和风味感官品质的变化,及病菌浓度和树龄对病程发展的影响。【结果】沙田柚嫁接病芽后,黄龙病菌浓度保持在较低水平(Ct28)时,植株叶片的黄龙病症状表现不明显,老叶轻微斑驳黄化,新叶轻微均匀黄化,抽梢正常。与健康植株(Ct35)相比,低黄龙病菌浓度(28Ct32)的植株,叶片症状、果实产量和各品质指标均无显著变化;随着发病程度的加深,高黄龙病菌浓度(Ct26)的柚树叶片出现典型斑驳黄化症状,单株柚果总产量和总结果数显著降低,果实变小变轻,着色不均匀,可食率、出汁率、可溶性固形物含量、甜味度、果肉饱满度和综合风味显著下降,酸味度和异味度反而显著提高,失去食用价值。【结论】沙田柚黄龙病病程进展较慢,但随着发病程度加深,其经济价值受到严重影响。本研究可为评价柑橘黄龙病对沙田柚品质的影响提供科学依据,为解析柚类植物的黄龙病耐性机理提供理论支撑。

Effects of citrus Huanglongbing pathogen on agronomic characteristic and fruit quality of Citrus maxima cv. Shatian Yu

Objective To clarify the effects of citrus Huanglongbing (HLB) pathogen on agronomic characteristic and fruit quality of Citrus maxima (Burm.) Merr. cv. Shatian Yu.Method Changes in pathogenic symptom of leaves, fruit external and internal qualities as well as sensory qualities of C. maxima after infected by HLB were studied by field investigation and laboratory test. The effects of bacterial concentration and tree age on disease development process were investigated.Result After C. maxima grafted with HLB-infected scions, when pathogen concentrations remained relatively low (Ct > 28), HLB symptoms were not evident with slight mottled yellow old leaves, slight uniform yellow new leaves and normal shooting. Compared with healthy plants, leaf symptom, fruit yield, and all fruit quality indexes of C. maxima infected by HLB pathogen at the concentration of 28 < Ct < 32 had no significant changes. With the increase of HLB affection, C. maxima infected by HLB pathogen at the concentration of Ct < 26 showed typical mottled yellow leaves, total yield per plant and fruit number per plant decreased significantly, fruits were smaller and lighter with variable color. The percentage of edible fruit and juice extraction rate, soluble solid content, sweetness, plumpness and overall flavor significantly decreased, while acidity and odor degree significantly increased. The fruit lost edible value.Conclusion The disease progress of HLB-infected C. maxima is slow, but the economic value of plant is seriously affected with the increase of morbidity degree. This study provides a scientific basis for evaluating the effect of HLB on C. maxima fruit quality and offers theoretical supports for analyzing the HLB tolerance mechanism of grapefruit plants.