土霉素对柑橘黄龙病的防治效果及对柑橘产量和品质的影响

Inhibition effect of oxytetracycline on citrus Huanglongbing and its effect on citrus yield and quality

为有效防控柑橘黄龙病,于2017年在佛罗里达大学柑橘研究与教育中心的奥本代尔市柑橘试验场进行田间试验筛选黄龙病的防治药剂及其浓度,测定注射土霉素后叶片中柑橘黄龙病菌亚洲种Cadidatus Liberibacter asiaticus、土霉素、淀粉含量、柑橘产量、出汁率、可溶性固形物含量和酸度,显微镜下观察注射土霉素后淀粉粒的分布。结果表明,浓度为1.6 g/株土霉素处理180 d后柑橘叶片中黄龙病菌亚洲种含量减少幅度最大,为91.78%;注射浓度为1.6 g/株土霉素后7 d,叶片中土霉素含量达142.2μg/kg,注射后11 d叶片中土霉素含量达到最大,为239.8μg/kg,注射后45 d叶片中土霉素含量低至99.6μg/kg以下;注射后7~90 d,叶片中黄龙病菌亚洲种含量呈波浪形变化,注射90 d后叶片中黄龙病菌亚洲种含量一直处于增长趋势,叶片中黄龙病菌亚洲种含量总体随着土霉素含量的升高而降低;注射浓度为1.6 g/株土霉素后,叶片中淀粉含量大幅度下降,60 d时达到最低值,为3.3μg/mm2,90 d时达到峰值,为14.5μg/mm2;单株产量为16.7 kg,与注射浓度为0.8 g/株土霉素处理差异不显著,但均显著高于其它2个处理;柑橘出汁率、可溶性固形物和酸度均与清水对照差异不显著。表明土霉素可有效抑制黄龙病菌亚洲种,减少柑橘叶片内淀粉含量,增加柑橘产量,但对果实品质未产生显著影响。

In order to prevent and control citrus Huanglongbing effectively,a field experiment was conducted in the Auburndale orchard,Citrus Research and Education Centre,the University of Florida in2017;antibiotic control agents were screened;Asian species of citrus Huanglongbing(Cadidatus Liberibacter asiaticus)in leaves were determined after trunk injection;the changes of oxytetracycline and starch content were monitored and simulated;the citrus yield,juice yield,soluble solids content,and acidity of citrus were measured,and the distribution of starch was observed under microscope after trunk injection.The results showed that the content of C.Liberibacter asiaticus in leaves decreased the most by 91.78%180 days after treatment with 1.6 g/plant oxytetracycline.The content of oxytetracycline in leaves reached 142.2μg/kg at day 7,reached the maximum 239.8μg/kg at day 11,and 99.6μg/kg at day 45 after trunk injection with 1.6 g/plant oxytetracycline.The content of C.Liberibacter asiaticus in leaves exhibited a wavy curve during 7-90 days and increased after 90 days.The content of C.Liberibacter asiaticus decreased with increasing oxytetracycline content.The starch content in leaves decreased significantly,reaching the lowest value of 3.3μg/mm2 at day 60 and reaching the peak of14.5μg/mm2 at day 90 after trunk injection with 1.6 g/plant oxytetracycline.There was no significant difference between the fruit yield in the treatments with 1.6 g/plant(16.7 kg)and 0.8 g/plant oxytetracycline,but they was significantly higher than that in 0.4 g/plant treatment and water control,but there was no significant difference between the treatment with 1.6 g/plant and water control in juice yield,soluble solids,acidity,and other parameters.It suggests that oxytetracycline can effectively inhibit C.Liberibacter asiaticus,thus reducing the starch content in the leaves of Honglongbing diseased plants and affecting the yield of citrus,but it has no significant effect on the quality of citrus.