Yield and Yield Related Parameters of Tomato (<i>Lycopersicon esculentum</i> Mill.) Treated with Paclobutrazol at Different Stages in North West Ethiopia

The effects of Paclobutrazol (PBZ) on fruit yield of tomato (Lycopersicon esculentumMill.) were investigated by spraying it on tomato seedlings grown in an open field. The treatments were 5 x 2 factorial combinations including five rates of PBZ (control, 1 kg ha-1, 2 kg ha-1, 3 kg ha-1and 4 kg ha-1) and two times of application (at 2 to 4 and 6 to 8 true leaf growth stages of tomato seedlings), arranged in a Randomized Complete Block Design, each treatment replicated three times. The objective of the study was to characterize the effect of rate and time of application of PBZ on the yield and yield related parameters of tomato. Time and rate of application of PBZ significantly increased harvest index, yield concentration and index of economic earliness, and decreased fruit set percentage, pericarp thickness, fruit diameter and percentage of class one fruit. Irrespective of the time of application, an increase in the rate of PBZ compared to the control significantly increased days to fruit maturity. Time and rate of application of PBZ were significantly interacted to increase; unmarketable fruit yield but decrease means fruit weight. Compared to the control, the interaction effects also produced two significant trends of variations on fruit yield per plant, fruit dry weight per plant, marketable fruit yield and total fruit yield. Significant reduction in yields was observed for diluted concentrations like 1 and 2 kg/ha a.i. of PBZ in the second time of application and 1 kg/ha a.i. of PBZ in the first time of application, whereas all other treatments produced significantly higher yields than the controls. On the contrary, time and rate of application of PBZ were found to be effective in improving economic earliness of tomato. As a whole, time and rate of application of PBZ resulted in two significant trends of variations (increasing and decreasing) on fruit yields of tomato. Hence, it could be possible to propose that more assimilate reallocation to the fruits are significant advantage of PBZ treatments contributing to the improvement of seedling quality at planting for increased seedling survival rate, better stress protection, early and more fruit production.