Effect of hand and chemical thinning on growth, production and fruit size in nectarine [Prunus persica (L.) Batsch var. nucipersica] cv. May Fire

The present investigation was conducted on 10-year-old May Fire nectarine plantations at the experimental orchard of Horticulture Research Station, Kandaghat, Himachal Pradesh during 2011-2012. Experimental trees were given the treatments, viz. retention of 3, 4 and 5 fruits per fruiting shoot after selective removal of fruits with hand at pea stage, foliar application of ethrel at 200 and 300 ppm, NAA at 40 and 60 ppm and thidiazuron at 20 and 40 ppm two weeks after petal fall and un-thinned control with three replications in randomized block design. Foliar spray of NAA at 40 ppm significantly increased the per cent fruit thinning, the yield of "A'' grade fruits, fruit size and rate of photosynthesis. However, the higher increase in shoot growth, tree volume, leaf area, leaf to fruit ratio were recorded under the treatment of hand thinning to retain 3 fruits per shoot. The lowest fruit drop was found with NAA 60 ppm and T-3 -Retention of 5 fruits per shoot in 2011 and 2012, respectively.