Field experiment was carried out at Melkassa Agricultural Research Center in 2012 and 2013 off-seasons using furrow irrigation with the objectives of evaluating the effect of four inter-row spacings (70, 80, 90, and 100 cm) and three intra-row spacing (20, 30 and 40 cm) on yield losses of tomato growing under open field production with fresh market (Bishola) and processing (Cochoro) type of determinate tomato cultivars. The treatments were arranged in 2x4x3 factorial in a split-split plot design in three replications. Data on major yield loss agents such as, blossom end rot, decay, insect, disease, sunburn, crack, catface and others minor disorders were collected; as well as total yield, percent of marketable and unmarketable fruit yield parameters were analyzed. Results of the study showed that inter-intra row spacing and cultivar had a significant (p<0.05) effect on the incidence of blossom end rot, decay, sunburn, catface, crack, other minor disorders, insect and diseases attacked fruit yield. In most cases for blossom end rot, decay, disease and insect attack and other minor disorders were higher at narrower inter and intra-row spacing combination but it varies with cultivars.
Whereas sunburn and cracked fruit were reasonably higher at wider inter-intra row spacing with cultivars. The highest total fruit yield of 100.45 and 92.55 t ha-1 were recorded for narrowest inter and intra-row spacing of 70 and 20 cm, respectively. However, the highest percentage of marketable fruit yield was obtained at 90 cm (64.80%) inter row spacing and 40 cm (56.7%) intra row spacing which have no significant difference with 30 cm. This suggests that on average more than 40% of total yield obtained in this study was unmarketable. Therefore, it will be so necessary to undertake more research on genetic improvement of the cultivars with advanced management options including plant spacing can better transform the present tomato production practices of growers.
