Effect of bagging materials on fruit growth and quality of guava (Psidium guajava L.) cv. Yen Song

Study on growth and quality of unbagged and bagged fruits of guava cv. Yen Song was conducted at Department of Horticulture, Kasetsart University, Nakhon Pathom province from May to August 1999. The bagging materials included polyethylene (white, blue or yellow in color), kraft paper, aluminum foil and polyester. Most of bagging materials could protect gases and humidity exchange in some levels excepted Remay polyester. Increased temperature and reduced light intensity inside the bags compared with nonbagged were found in all materials. The growth period of a guava fruit from anthesis to maturity was 15 weeks. During weeks 1-11, more rapid fruit growth was obtained when polyethylene bags were used. Fruit bagging decreased the defects caused by diseases and insects, and increased flesh firmness and flavor. Bagging did not significantly influence sensory evaluation. Bagging with blue polyethylene resulted in the highest pulp thickness, TSS/TA and ascorbic acid content while bagging with yellow polyethylene resulted in the highest fruit width, TSS and heat unit accumulation. There were no statistical differences in fruit length, pith diameter, the defects caused by sunburn and physical injury, fruit density and percent recovery among various treatments.