How Quantitative and Qualitative Traits of Thomson Navel Orange Affected by Citrus Red Mite, Panonychus citri

To examine the effect of Citrus Red Mite (CRM) damage on quantitative and qualitative characteristics of Thomson navel orange Citrus sinensis (L.) Osbeck, paired-treatment experiment, multiple treatment experiment, and regression/correlation methods were used. There were significant differences among the treatments in paired-treatment and multiple treatment experiments in terms of the average population per leaf of CRM of different life ages and concentration of chlorophyll in the leaves. Also, there were significant differences among the treatments in multiple treatment experiment in terms of the Total Soluble Solids (TSSs) of the fruit extract. In control treatment of the paired-treatment experiment, the highest concentration of chlorophyll (۷۹.۱۳±۱.۰۶) was observed when the population density of CRM was ۰.۴۸±۰.۰۹ per leaf. With increasing the mean number of CRM to ۱۰.۵۹±۱.۰۹ per leaf, chlorophyll content was decreased to ۶۲±۱.۱۵. Furthermore, the results showed that the storage life of the fruits in treatments with mean number of ۶.۳۳±۱.۸ mites per leaf was significantly reduced. The results of regression and correlation analysis on chlorophyll showed significant and negative relationship between these parameters and CRM population density. The results indicated that increasing the population density of CRM to ۱۰.۵۹±۱.۰۹ per leaf at the beginning of the season caused fruit drop and dry twigs. In addition, by increasing population density of CRM to ۵.۷۲±۰.۴۳ per leaf, the storage capability of the fruits was significantly reduced.

Keywords:

Citrus red mite , Crop loss assessment , Quality loss , Yield loss.