Growth, yield and postharvest qualities of tomato (Lycopersicon esculentum M.) as influenced by soil moisture levels and packaging

Tomato (Lycopersicon esculentum M.) is a fruit vegetable, and like most horticultural commodities is highly perishable. It is often exposed to stresses either imposed by other organisms (biotic) or arising from imbalance of environmental factors (abiotic). The effects of five different soil moisture levels [20%, 40%, 60%, 80% and 100% of the pot capacity (PC)] were studied in tomato (cv. ‘Moneymaker’) planted in plastic pots under greenhouse conditions, and then assessed for sustainable postharvest qualities including use of different types of packaging [non-packaged (control), perforated and non-perforated high density polythene bag (HDPE)]. The objective of this study was to determine the yield performance and the postharvest quality of tomato under varying soil moisture stress (water deficit). Field and laboratory trials were conducted at the Horticulture Research and Demonstration Field and Tissue culture laboratory respectively, Egerton University, from March to July 2010 (Trial 1) and from June to October 2010 (Trial 2). The experiments were carried out in a randomized complete block design (RCBD) and in a split-plot arranged in RCBD for both field and laboratory work respectively. Data collected was subjected to Analysis of Variance (ANOVA) and mean separations were done using Duncan Multiple Range Test (DMRT) at 5% level of significance. Water deficit stress resulted into decreased growth and yield of tomato but enhanced its post-harvest qualities. Plant height was affected by the amount of water applied, although inconsistently. Tomato fruit yield was also affected significantly by soil moisture levels. The highest fruit yield (70 ton/ha) was recorded in the well watered (control) plants; the highest flower abortion (80 - 94 %) and the smallest fruit diameter were observed in the severely stressed plants (20 % of PC). Soil moisture stress influenced tomato post-harvest qualities. The higher the water content, the higher the weight loss and the faster the fruit losses its firmness and develops a speedy fruit colour change. Fruit weight was reduced by 32 % in unpackaged fruits (control) while packaged fruits developed a faster fruit colour change and increased the fruit total soluble solids (5.5%). The fruit total soluble solid was decreased and the titrable acidity was higher in fruits from the well watered plants. Unpackaged fruits had the highest level of titrable acidity (12.6 -13.2%) and lost their firmness faster. Severe moisture stress improved tomato fruit quality in reducing fruit acidity and in increasing the fruit total soluble solids (5.8%) and preserving its firmness. Packaging positively influenced the tomato fruit quality and extended tomato shelf life.