Using Roma Tomato to Study the Limits of Deficit Irrigation

A greenhouse study of deficit irrigation was conducted to understand the fraction of optimum evapotranspiration water requirement that limits growth and development of Roma tomato. Seedlings of the crop were germinated and transplanted into 20 cm diameter pots in a mixture of 2: 1 topsoil and perlite. The 200 seedlings were arranged in a randomized complete block replicated five times such that each block contained 40 seedlings. Deficit irrigation treatments included 100% (control), 75%, 50%, and 25% of the amount of control freshwater. Crop growth and development parameters studied include relative growth rate, fresh and dry vegetative biomass accumulation, chlorophyll content, leaf area, stomatal conductance, and number of flower buds and flowers as a consequence of deficit irrigation. Results of the study indicate a two-tier effect of deficit irrigation on the crop with no growth loss at the vegetative growth phase even at 50% irrigation, but a significant reduction in flower bud initiation and flowering even at the 75% irrigation. Based on these results, it is recommended that deficit irrigation up to 50% of optimum evapotranspiration requirement of Roma tomato be adopted as a water conservation strategy at the vegetative growth phase, and a return to the full evapotranspiration water requirement at the onset of flower bud initiation.