Effect of PRSV Infection on Pigment Content and Assimilation of Carbohydrate in Carica papaya L.

The initial dry weight and the rate of respiration of diseased leaves per unit area were higher in diseased leaves than in healthy leaves. Net productivity in healthy plants was higher than in diseased ones (211.5 mg/cm²/hr against 111.2 mg/cm²/hr.). Gross productivity in healthy leaves was much higher (375.9 mg/cm²/hr) than in diseased leaves (140.9 mg/cm²/hr). The total chlorophyll chl. a, chl. b and carotenoid content were lower in infected tissue (67.5%, 38.7%, 2.7% & 0.3%, respectively). Nitrogen and protein contents were higher in infected tissue compared to healthy counterparts (3.7 & 10.1%, respectively). The carbohydrate content was found to be lower in infected tissue (11.4%, 9.3% & 8.2% for reducing sugars, non-reducing sugars & starch, respectively). The average yield loss suffered by the test plant was 61.3%. The economic value of the infected host was reduced to only 38.7%.