Differential response of muskmelon (Cucumis melo L.) cultivars to deficit irrigation

Deficit irrigation (DI) can influence melon yield and fruit quality, but root growth and phytochemical responses to DI are not well understood. A two-year study investigated the impact of deficit irrigation (50 vs. 100% crop evapotranspiration, ETc) on three melon (Cucumis melo L.) types, 'Mission' (cantaloupe; reticulatus), 'Da Vinci' (tuscan; reticulatus) and 'Super Nectar' (honeydew; inodorus) on a silty clay soil in southwest Texas. DI caused a significant yield reduction in 'Super Nectar' (38%), 'Da Vinci' (30%) and 'Mission' (24%). DI had no adverse effect on fruit quality; rather, it increased total soluble solids content (23%) in 'Mission, 8-carotene content (25%) in 'Da Vinci' in 2011 and ascorbic acid content (42%) in all cultivars in 2012. The minirhizotron data showed that 'Mission' under DI maintained a consistent increase in root length intensity (La) till harvest. At the fruit setting stage, the photosynthetic rate (Pn) was considerably reduced under DI in all cultivars, but it resumed in 'Da Vinci' and remained high throughout the growth period in 2011. Agronomic water use efficiency (WUE; kg ha(-1) mm(-1)) was also improved in 'Mission' (13%) in 2012 but decreased in 'Super Nectar' (21%) in 2011. In summary, DI was able to save 41% of irrigation water in 'Mission' and 'Da Vinci' with a moderate reduction in marketable yield. These responses may be linked to improvements in La (Mission') and maintenance of Pn ('Da Vinci'). DI may not be applicable for the honeydew melon 'Super Nectar, as it reduced Pn, La, yield and WUE.