Effect of plant population, fruit and stem pruning on yield and quality of hydroponically grown tomato

A study was conducted in 2009 to 2010 and 2010 to 2011 to investigate the effect of plant population, and fruit and stem pruning of hydroponically grown tomatoes in a 40% (black and white) shade-net structure at the ARC-Roodeplaat VOPI. An open bag hydroponic system containing sawdust as a growing medium was used in this experiment. Tomato plants were subjected to three plant populations (2, 2.5 or 3 plants/m2), two stem pruning treatments (one stem and two stems) and three fruit pruning treatments (four fruits, six fruits per truss, and no fruit pruning). Experimental layout was a complete randomized block design with three replicates. Data on fruit number, fruit mass, unmarketable yield, marketable yield and total yield was collected from 10 plants for all treatments. Plants pruned to two stems with zero fruit pruning or pruned to six fruits produced significantly higher marketable and total yield, as compared to the other treatments. Plant population of 3 plants/m2, resulted in significantly higher marketable yield of tomatoes, compared to 2.5 and 2 plants/m2. Results showed that tomato yield and quality can be effectively manipulated by plant population and stem pruning, while fruit pruning had only a limited effect.   Key words: Fruit cracking, open-bag hydroponic system, plant population, pruning, shade-net structure, fruit yield.