Effect of GA3 and Urea on Yield and Fruit Quantitative and Qualitative Characteristics of 'Satsuma' Mandarin (Citrus unshiu)

In this investigation, because of the need for increasing fruit set and yield and also improving fruit quality and quantity characteristics, GA(3) and urea were sprayed in different concentrations alone and their combinations on ten years old 'Satsuma' mandarin trees on a citrange rootstock during late bloom. This experiment was done in Mahdasht Garden of Sari City in 2010. The experiment was done in a Randomized Complete Block Design, on 16 May with 4 replication and 6 treatments including: control, GA(3) (15 mg L-1) GA(3) (15 mg L-1) + urea (1%), GA(3) (30 mg L-1), GA(3) (30 mg L-1) + urea (1%) and urea (1%). The results showed that percentage fruit set decreased in all treatments, but this reduction was significant only for the GA(3) (15 mg L-1) treatment. In contrast, the GA(3) (15 mg L-1) treatment significantly reduced the June drop percentage and increased overall the fruit retention percentage compared with control, whereas the lowest amount of fruit retention was observed in the GA(3) (30 mg L-1) + urea (1%) treatment. The different GA(3) and urea treatments had no effect on increasing yield. Also the GA(3) (15 mg L-1) treatment increased significantly peel weight to peel diameter compared with the urea treatment. This translated to improved peel density and firmness and also decreased puffiness. Because of decreasing peel diameter in all treatments, treated fruit had thicker peel but greater firmness.