Seasonal changes of endogenous hormones, carbohydrates and nitrogen in loquat (Eriobotrya Japonica Lindl) leaves

In this research, Gold Nugget and Akko XIII loquat cultivars were used. Leaf samples were taken from the loquat trees in morphological differentiation phase (August), initially of flower inflorescence (October), fruitset (February) and the initial time of fruit maturation period (May). Taken samples, amounts of free-, bound-, and total-forms of some endogenous plant hormones [ indole-3-acetic acid (IAA), gibberellik acid (GA3), abscisic acid (ABA), zeatin (Z)], carbohydrates (total sugar and starch), nitrogen (N) and carbohydrate/nitrogen (C/N) were determined. The materials used in this research were taken from the loquat trees which were planted in 1993 from Citrus and Greenhouse Research Instute İn Antalya. The analyses of taken samples were made at the central laboratory of Agricultural Faculty, physiological laboratory of Horticultural Department and High Performance Liquid Chromatography (HPLC) analyses were made at the central research and application laboratory of Medicine Faculty, Akdeniz University. According to the results, IAA showed to the minimum level in August, it reached to the maximum level in May at both of loquat cultivars. Endogenous GA3 was found rather low level in morphological differentiation and flowering periods, its level was found to the maximum in May (shoot development period) at both of loquat cultivars. ABA levels reached to the maximum level in August (morphological differentiation 111period), it decreased during the growing and development processes and not detected during February (the presence of fruMets). But, ABA level was found some increase in May (the initial time of fruit maturation). In the first year, endogenous Z increased during the flowering period and this increase was found to the maximum level in the fruit set period at both of loquat cultivars. But, it showed the repeatedly decrease in the fruit maturation period. In the second year, it was obtained opposite situation in February in Gold Nugget loquat cultivar. At Akko XIII loquat cultivar, it was obtained stationary progress during the flowering period and Z increased in May at both of loquat cultivars. It was determined that total sugar levels increased according to fruit maturation while starch and total carbohydrates decreased in this period at both of these loquat cultivars. N level and C/N ratio were found maximum in the morphological period (except of Akko Xni loquat cultivar, August 2000 sample), these were decreased according to growing and developmental periods. KEY WORDS: Loquat, Eriobotrya japonica Lindl., ABA, GA3, IAA, Z, HPLC, total sugar, starch, nitrogen COMMTTEE: