) citrus aurantifoliaswing نقش اتيلن به عنوان تنظيم كننده رشد بر جذب عناصر كم مصرف در ليمويي آب

THE ROLE OF ETHYLENE AS A GROWTH REGULATOR ON MICRONUTRIENTS UPTAKE IN MEXICAN LIME (CITRUS AURANTIFOLIA SWING)

Recently the effect of ethylene on induction of physiological and morphological stress responses of iron deficiency, especially on strategy I plants, has been investigated. Also the role of these responses on iron and other cation uptake by plant roots and on the influence of nutrient deficiency on these responses were experimented. The importance of ethylene effect as a plant hormone on cation uptake mechanism caused that we study its influential effects on micronutrients uptake in citrus. Therefore, Mexican sourlime (Citrus aurantifolia Swing) seedling roots were treated by ethephon and root morphological changes, the concentration of Fe, Mn, Zn and Cu in roots and leaves were studied. The results showed that ethylene induced root growth by high axillary root production and also enhanced root hair formation and subapical root swelling. Moreover, ethylene increased micronutrient uptake, specially Fe and Mn by roots. The indirect effect of ethylene through induction of root growth on leaf area expantion reduced specific leaf weight (SLW) and conduced dilution effect in leaves. Under this condition, calculation of leaf micronutrient concentration based on the dry weight, gave little information about them in comparison with control, while the content of this elements per leaf presented better commentry about them. This index showed that the amounts of Fe, Mn, Zn and Cu enhanced in leaves. Local effects of ethephon on Fe and Mn uptake by roots indicated that physiological responses had higher efficiency than morphological changes in respect of Zn and Cu that were mostly affected by roots growth. Thus, ethylene have effective role on Mexican lime roots micronutrient uptake via physiological or morphological changes.