TRANSPLANT GROWTH AND STAND ESTABLISHMENT OF BELL PEPPER (CAPSICUM ANNUUM L.) PLANTS AS AFFECTED BY COMPOST-AMENDED SUBSTRATE

The objective of this study was to determine the effects of using compost on bell pepper transplant growth and subsequent fruit yield after transplanting in the field. Bell pepper, ‘X3R Wizard’, was seeded on the spring of 2000. Transplants were grown using (1) commercial transplant growing substrate (Pro-Mix PGX, 70% peat moss) routinely used to grow bell pepper transplants and (2) the same substrate amended with on-farm produced compost (Gromor Organics Inc., Tifton, Georgia). Compost-amended (20% by volume) substrate significantly increased transplant height by 10%. In addition, leaf area, shoot dry weight, root dry weight, and plant height were significantly higher for transplants grown in compost-amended substrate 51 days after seeding. Transplants grown in compost-amended substrate also yielded 20% more fruit than transplants grown in non-amended substrate. In a follow-up study in 2002, the effects of amending the substrate with various rates of compost (from 0% to 50% by volume) on transplant growth were determined. Forty-two days after seeding, plants grown in substrate amended with 0% and 10% compost were shorter and had lower root dry weights compared to plants amended with ≥20% compost rate. In conclusion, our results show that the utilization of compost as a substrate amendment resulted in high quality transplants with increased vigor. This growth enhancement was partly due to the mineral nutrients contained in the compost, although compost was unable to supply all the nutrients needed by the plants. The results of this study did not show any beneficial effects on fruit yield attributed to using compost for transplant production. INTRODUCTION Composting is the practice of using biological reduction of organic wastes to humus or humus-like substances (Stratton et al., 1995). Through the process of composting, biodegradable organic wastes are transformed into a product that can be utilized as a soil amendment or fertilizer. Recently, there has been a trend towards agricultural sustainability that has motivated a new interest in manure and compost utilization. Compost application improves the physical, chemical and biological properties of soils, and represents an environmentally-friendly means of disposal of organic wastes (Dick and McRoy, 1993; Hill and James, 1995; Mays et al., 1973). The application of compost has resulted in variable crop responses, from increases, to decreases and no changes in crop yields (Ozores-Hampton et al., 1998; Roe, 1998). In preliminary studies, we found that at first harvest, 70 days after transplanting, the marketable yield of pepper was twice as large when using transplants produced in compost-amended substrate compared to that using transplants grown without compost (8.70 t/ha and 3.69 t/ha, respectively) (Granberry et al., 2001). After weights of all marketable peppers (for all harvests) were combined, transplants grown in compostamended substrate yielded 20% more than transplants grown in non-amended substrate. The difficulty to predict the effects of compost on plant growth and yield derives from the differences in age (maturity) and composition (nutrient content, C:N ratio, etc.) among composts. Composts, used alone or in mixtures with other materials, can serve as horticultural potting media in organic or sustainable production systems. There is an increasing interest among transplant growers to find alternative materials for producing Proc. IV IS on Seed, Transplant and Stand Establishment