Effects of water deficit and arbuscular mycorrhizal fungi on growth, yield and fruit quality of processing and fresh market varieties of tomato (Lycopersicon esculentum Mill.)

The effects of increasing water deficit and arbuscular mycorrhizal fungi inoculation on growth, yield and fruit quality of fresh market and processing tomato varieties were studied. At the start of fruit set, mycorrhizal uninoculated and inoculated tomato varieties were exposed to 0kPa, 50 kPa, 100 kPa and 200 kPa soil-water tension levels. Reduction in shoot biomass, fruit weight and total fruit biomass were observed in both tomato varieties as response to water deficit where reduction was least at 50 kPa tension level. Whereas water deficit increased water use efficiency of fresh market variety, the harvest index of both varieties was not significantly affected. Significant increases in fruit firmness, total soluble solids, titratable acidity and ascorbic acid content of fresh market variety were observed whereas the response of processing variety differed. Fruit firmness did not vary in processing variety while significant reduction in total soluble solids was observed at 200 kPa tension level. Increase in titratable acidity of processing variety was observed at 50 kPa and 100 kPa tension levels. Water deficit significantly reduced fruit water content and improved fruit shape of the processing variety but not the fresh market variety. Inoculation of arbuscular mycorrhizal fungi, in general, did not show significant effect on the different parameters measured. Results of the study showed that amount of water applied can be reduced by exposing the tomato plants to 50 kPa water tension during fruit set with minimal effect on growth and yield. Reduction in fruit yield and fruit weight due to water deficit can be compensated by the improvement in fruit quality and water use efficiency. The study also showed that differences in response to water deficit exist between the two tomato varieties.