ارزیابی تاثیر مینوز برگ مرکبات، Phyllocnistis citrella Stainton (Lep.: Gracillaridea)، بر برخی صفات فیزیولوژیکی گونه‌های مختلف مرکبات در شرایط آزمایشگاه

Study of some biochemical traits of different cultivars and species can help to identify effective mechanisms for resistance of plants to pests. The citrus leaf miner, Phyllocnistis citrella Stainton, is one of the most common citrus pests in nurseries and young gardens, causing heavy damage every year. In this study, from leaves of four citrus species including Orange (Citrus. sinensis L.), Key lime (C. aurantifolia L.), Sweet lemon (C. limetta L.) and Sour orange (C. aurantium L.) damaged with citrus leaf miner and healthy leaves located in the Citrus Garden of Department of Plant Protection, were sampled at the Shahid Chamran University of Ahvaz. The amount of soluble carbohydrates (pentose, hexoses and total sugars), proline and calcium, magnesium and potassium elements were evaluated at two healthy (control) and damaged levels. Data statistical analysis was done in a completely randomized design with three replications and mean comparison with Tukey's test was performed by SPSS software. The results showed that there was a significant difference between the two control and damaged levels in all measured parameters. The levels of soluble carbohydrates in damaged leaves of all species significantly decreased compared to healthy leaves. The highest mean of pentose sugars in healthy Sour orange and lowest in damaged Orange was 226.21 ± 1.79 and 52.14 ± 0.8 mg / kg of dry leaf weight, respectively. Comparison of mean of hexose sugars showed that the highest mean recorded in healthy Sweet lemon 546.90 ± 2.43 and the lowest mean in damaged Orange (76.23 ± 1.25 mg / kg of dry leaf weight). In the study, the average total sugar content of healthy Orange (343.99 ± 3.55) had the highest mean and the lowest mean was in damaged Orange (144.72 ± 2.71 mg / kg of dry leaf weight). Also, the amount of proline in damaged leaves of Sour orange and Orange species increased more than controls compared to Key lime and Sweet lemon. The highest mean of proline in damaged Sour orange and the lowest mean in healthy Sweet lemon and healthy Orange were 158.78 ± 1.39 and 32.09 ± 1.31 and 23.97 ± 0.8 mg / kg of leaf wet weight, respectively. In evaluating the elements of the experiments results, the potassium element were significantly higher in the damaged leaves of the different species than the control treatments. The highest mean in damaged Key lime (3350 ± 21.47) and the lowest mean in healthy one (729 ± 3.44 mg / kg).It can be concluded that damaged plants use carbohydrates to produce proline, which is a mechanism of resistance building. Also, by increasing the concentration of potassium in tissues under stress, they cause structural resistance in the plants.