INVESTIGATION ON HEAT REQUIREMENTS AND FRUIT GROWTH OF SOME EARLY MATURING APRICOT CULTIVARS IN SEMIARID CONDITIONS

摘要

For temperate-zone fruit species, a certain total heat requirements are needed in order to obtain mature fruits. Fruit development process changes in different fruit groups. Determination of fruit growth stage and heat requirements are the most important cultural practice in orchard management, such as time of irrigation, fertigation, thinning and harvesting, etc. This study was conducted on heat requirements, fruit growth and development of ‘Bella d’lmola’, ‘San Castrese’ and ‘Sungiant’ apricot cul- tivars in Sanliurfa (Turkey) during 2011 and 2012. Heat requirements in the phenological period from dormancy breaking to fruit maturation period were determined in apricot cultivars. Fruit weight and fruit volume of three apricot cultivars were determined at five-day intervals from fruit setting till fruit harvest. Fruit sampling for TSS and titratable acid contents was made with ten day intervals just after thirty five days of full bloom and with five day intervals at the close harvest stage. The total heat requirements between bud swelling (BBCH Code: 51) and fruit maturation period (BBCH Code: 89) in apricot cultivars was determined as 21 333 (‘Bella d'lmola’) - 25 024 (‘Sungiant’) GDH. In these cultivars, three developmental stages were observed as “fast,”- “slow,”- and “fast” during the fruit growth. The significant increases in fruit weight and volume in all apricot cultivars were observed during the third growth stage. During the growth period of fruit TSS content continuously increased, whereas titratable acid content decreased. It was determined that the cultivars for fruit maturation should pass at least 65 (‘Bella d'lmola’) - 80 days (‘San Castrese’) after full blooming.