Efficacy of some chemicals for crop regulation in Allahabad Safeda guava under coastal Indian conditions of Odisha.

Abstract

A crop regulation study was carried out on sixteen-year-old orchard of guava cv. Allahabad Safeda during 2016-18 to evaluate the efficacy of some chemical defoliants for avoiding rainy crop and inducing profuse flowering during rainy season (Mrig bahar) in order to get heavy crop load during desirable season, i.e., winters. The experiment was laid out in randomized block design with 13 treatments consisted of ethephon (200, 400 and 600 ppm), ά-naphthalene acetic acid (500, 750 and 1000 ppm), ortho-phosphoric acid (1, 2 and 3%), and urea (5, 10 and 15%), and water spray as control. Foliar application of chemicals was done in the first week of May. Application of ethephon 600 ppm not only resulted in maximum defoliation (95.69%) and fruit abscission (98.61%) of rainy-season crop (Ambe bahar) but also recorded maximum flushing (19.17 shoots/m of branch), flowering (49.74%), No. of fruits/plant (146.14) and fruit yield (28.76 kg/plant) for winter crop. Ethephon treated plants produced smaller fruits (203.26±4.78 g) as compared to control (227.66 g), whereas, urea treated produced bigger fruits (234.05±4.09 g). With regard to fruit quality, none of the crop regulating treatments exhibited significant variation over control for pulp TSS and vitamin C, however, significant improvement in antioxidant properties was recorded with ethephon (200-600 ppm) and urea (10-15%) treatments. Fruits harvested from 600 ppm ethephon sprayed plants were superior in quality and scored the highest values for TSS: acid ratio (22.96), total phenolic content (147.25 mg GAE/100 g FW), total flavonoids (36.61 mg QE/100 g FW), ferric reducing antioxidant power (29.09 mM Fe(II)/100 g FW) and scavenging activity (74.29%).