Effect of chemical thinning, gibberellic acid and pruning on growth and production of nectarine (Prunus persica (L.) Batsch var. nucipersica) cv. May fire

Abstract

The present investigation was carried out on 12-year old trees of nectarine (Prunus persica (L.) Batsch var. nucipersica) cultivar May Fire raised on wild peach seedling rootstocks, Farmer’s orchard at Kotla- Barog in District Sirmour during the years 2014 and 2015. In this experiment, experimental trees were subjected to seventeen different treatments;T1: Pruning to retain 60 fruiting shoots tree-1 (control), T2: Pruning to retain 50 fruiting shoots tree-1, T3: Pruning to retain 40 fruiting shoots tree-1 ,T4: NAA 40 ppm, 2 WAPF (week after petal fall) ,T5: Ethrel 300 ppm, 2 WAPF, T6: GA3 100 ppm, 4 WAPF, T7: GA3 200 ppm, 4WAPF, T8: GA3 100 ppm, 6 WAPF T9: GA3 200 ppm, 6 WAPF, T10: Pruning to retain 50 fruiting shoots tree-1 + NAA 40 ppm (T4), T11: Pruning to retain 50 fruiting shoots tree-1 + Ethrel 300ppm (T5), T12: Pruning to retain 50 fruiting shoots tree-1 + GA3100 ppm (T6), T13: Pruning to retain 50 fruiting shoots tree-1 + GA3 100 ppm (T8),T14: Pruning to retain 40 fruiting shoots tree-1 + NAA 40 ppm (T4), T15: Pruning to retain 40 fruiting shoots tree -1 +Ethrel 300 ppm (T5),T16: Pruning to retain 40 fruiting shoots tree -1 + GA3 100 ppm (T6), T17: Pruning to retain 40 fruiting shoots tree -1 + GA3 100 ppm (T8), pertaining to alternative approach to chemical thinning, chemical thinner were more effective in improving the production of superior grade fruits than reducing the crop load directly by pruning or indirectly by GA 3 (Gibberellic Acid) treatments. Treatments with NAA (naphthalene acetic acid) at 40 ppm when applied two weeks after petal fall reduced the crop load to the greatest extent and improve the yield of superior grade fruits and increase the leaf to fruit ratio and decrease the fruit drop. Pruning to retain 40 fruiting shoots tree-1 + NAA 40 ppm, 2WAPF increased the shoot growth (160.80, 170.20cm), tree height (3.70,4.50 cm), tree spread (2.84,3.60), leaf area (42.71, 40.63 cm) during both the year. However, effect of chemical were less pronounced on trees subjected to severe pruning.