Yield of determinate tomato cultivars grown in a closed hydroponic system as affected by plant spacing

ABSTRACT In South Africa there are no established spacing recommendations for determinate tomato cultivar production under closed hydroponic systems. This study was conducted to determine yield and quality of hydroponically grown determinate tomato cultivars at different plant densities. Four determinate tomato cultivars (Dynimo, Mariana, Mion and Sama) were subjected to four plant densities (10, 16, 20 and 25 plants/m2) during the spring/summer and summer/fall seasons. Experimental layout was a randomized complete block design in a factorial scheme of four plant spacing x four cultivars with three replicates. There were no significant differences in marketable yield between the cultivars tested during the spring/summer and summer/fall seasons. Cultivar Mion showed higher incidence of blossom end rot, while Mariana showed the highest fruit rot during the spring/summer season as compared to the other cultivars. During the spring/summer season, marketable yield increased with increased plant density with the highest yield obtained at 25 plants/m2 followed by 20 plants/m2. During the summer/fall season, plant density did not show a significant effect on total and marketable yield although a tendency for declined yield with increased density was observed. Number of fruit per plant as well as fruit size decreased with increased plant density during both seasons which did not have an effect on overall yield per plot area. Increasing the plant density to 25 plants/m2 can improve marketable yield of determinate tomato cultivars during spring/summer season while using a plant density of 10 plants/m2 will be more cost effective during the summer/fall season. This information will enable farmers to optimise yield and quality of determinate tomato cultivars under closed hydroponic systems. RESUMO Na África do Sul não há recomendações de espaçamento estabelecidas para a produção de cultivares de tomate em sistemas hidropônicos fechados. Determinou-se o rendimento e a qualidade de cultivares de tomate de crescimento determinado (Dynimo, Mariana, Mion e Sama) em hidroponia e densidades de plantio (10, 16, 20 e 25 plantas/m2) durante primavera/verão e verão/outono. O delineamento experimental foi em blocos ao acaso, em esquema fatorial de quatro espaçamentos de plantas x quatro cultivares com três repetições. Não houve diferenças significativas no rendimento comercial entre as cultivares testadas nas duas épocas de plantio. A cultivar Mion apresentou maior incidência de p