Effects of Plastic Mulch Types on Crop Performance of Drip Irrigated Winter and Summer Peppers 1 Megh R. Goyal, Ruben Guadalupe Luna, Luis E. Rivera and E. R. de Hernandez 2 ABSTRACT Plant growth, yield, fruit quality and fruit performance characteristics were evaluated for transparent (T1)-, white (T2)-, black (T3)-, silver coated black plastic (T4) mulched, organic mulched, (T5) and non-mulched (T6) peppers (var. Cubanelle) under drip irrigation during winter and summer of 1981-82. Values of plant growth parameters, fruit weight, fruit width and length were significantly higher at 5% level during the winter than during the summer in each treatment thus resulting in increased winter pepper yield. T1 plots caused lowest pepper yield at 5% compared to yield of T2, T3, T4, T5 and T6. The percentage of defective peppers was highest at 5% level during the summer than during the winter. Second harvest had highest fruit weight at 5% level in comparison with third and fourth harvests during the winter and summer. INTRODUCTION Separation of products into various grades on the basis of quality and size is the greatest stimulus to better methods of marketing because this grading helps growers to pool their products in cooperative marketing associations in order to share equitably in the season's sales. Any varia- tion in appearance, texture, taste and other physical characteristics usually make a difference in the selling price of produce. To what extent USDA grading standards are applicable to vegetables grown in Puerto Rico remains to be determined. About 83% of total vegetable consump- tion in Puerto Rico is imported. Local demand for vegetable products and fresh vegetables (5) as well as the interest of local industry in marketing fresh vegetables, is increasing. Albergts and Howard (1) reported that the size and number of pepper fruits per plant were increased by mulch treatment. Early growth and marketable yield of pepper were greatest with full bed mulch (1, 5, 6, 8, 10, 11 ). Aluminum foi l mulch contributes to few virus symptoms in peppers (2, 5, 7) and increased vegetative growth (3, 5, 11). Priester (9) has outlined guidelines for grading of Cubanelle peppers. A study to determine the possibility of using different plast ic mulches ' Man uscript submitted to Ed itorial Board August 29, 1983. This study was conducted under H326(S-143 ), Southern Region Research Project- "Trickle Irrigation in Humid Regions" and H -284, "Grading of Vegetables". 2 Associate Agricultural Engineer, Associate Horticulturist , Research Assistant, and Assistant Food Techno logist, respectively, Agricul tura l Experiment Station, University of Puerto Rico, Mayagtiez Campus, Rio Piedras, PR. 297