Modulation of growth physiology yield fruit quality attributes and prsv expression of tnau papaya co8 through bioregulators

Abstract

A field trial was conducted during 2017-2019 at College orchard, Horticultural College newlineand Research Institute, Tamil Nadu Agricultural University, Coimbatore with the main objective newlineto analyze the influence of bioregulators on growth, yield, fruit quality attributes and disease newlineseverity of PRSV in papaya variety TNAU Papaya CO.8. The trial was laid out in Factorial newlineRandomized Block Design with three replications. The study involved two factors viz., growth newlineretardants as factor I and bioregulators promoting stress tolerance as factor II. The treatments newlineinvolving growth retardants were water spray (G1) as control, 250 ppm of prohexadione calcium newline(G2), 500 ppm of mepiquat chloride (G3) and 500 ppm of chlormequat chloride (G4). Similarly, newlinebioregulators promoting stress tolerance (Factor II) comprised of water spray as control (S1), 100 newlineppm of methyl jasmonate (S2), 100 ppm of salicylic acid (S3) and 0.6 g L-1 newlineof strobilurins (S4). newlineThe bioregulators were applied as foliar spray at fourth and eighth months after transplanting. newlineInitially, growth retardants were sprayed and one week after that, the bioregulatorspromoting newlinestress tolerance were sprayed. newlineObservations were made on morphological, physiological, fruit physical traits, leaf newlinebiochemical analysis and post-harvest quality attributes. Scoring for papaya ring spot virus newlineincidence was also carried out at 3 newlinerd, 5th, 7th and 9th months after transplanting. newlineSignificant treatment differences were observed for important parameters studied. Among newlinethe treatments, the lowest plant height was observed in G4S1 at flowering stage (104.09 cm) and newlineG2S1 at fruiting stage (140.79 cm). The absolute control registered a plant height of 123.35 cm newlineand 168.74 cm at flowering and fruiting stage. Stem girth was higher in the treatment G4S4 at newlineflowering stage (24.53 cm) and G4S1 at fruiting stage (29.29 cm). Earlier flowering was observed newlinein G2 (110.53 days) while the bioregulators promoting stress tolerance and its combination with newlinegrowth retardants were non-significant. Earlier harvest w