Effects of manual and chemical fruit thinning on fruit size of 'Simeto' mandarin

Simeto' mandarin hybrid was obtained from a cross between 'Miho' satsuma and 'Avana seedless' mandarin at University of Catania. 'Simeto' mandarin is very productive with excellent fruit quality, but its heavy crop often causes complete inhibition of vegetative growth and consequently induces alternate bearing. Manual thinning and NAA treatment using three concentrations (350, 500 and 800 ppm) were performed at the end of June drop. NAA was effective in fruit thinning and fruit drop was positively correlated with the concentration applied. In all the thinning treatments, fruits were larger in size than those from the control. Although no significant differences were observed among treatments, it seems that NAA at 500 ppm would be suitable for fruit thinning.