Grafting Melons Increases Yield, Extends the Harvest Season, and Prevents Sudden Wilt in New England

Abstract

Melons (Cucumis melo var. reticulatis) are potentially a high value crop for New England, but production is limited by cool spring temperatures and sudden wilt. The sudden wilt syndrome in melon, attributed to both biotic and abiotic factors, is characterized by rapid wilting of vines either just preceding or during the harvest season, reducing melon quality and shortening the harvest period. We investigated the effects of grafting melons to rootstocks of interspecific hybrid squash (Cucurbita maxima × C. moschata), which have exhibited tolerance to soilborne diseases and cooler soil temperatures. In 2015, we compared the performance of ‘Halona’ melon grafted to two rootstocks, ‘Carnivor’ and ‘NH1320’, to that of nongrafted (NG) plants at two New Hampshire Agriculture Experiment Research Farms, Woodman (WRF) and Kingman (KRF). Pistillate flowering and melon harvests were 3 to 9 days earlier in NG than grafted (GR) plants. By harvest period, GR plant growth exceeded that of NG plants, and GR plants did not display wilting symptoms observed in NG plants. Total marketable yields were 57% and 90% higher for GR/‘Carnivor’ (47.8 and 45.0 Mg·ha−1) and 44% and 89% higher for GR/‘NH1320’ (43.9 and 44.9 Mg·ha−1) compared with the NG treatment (30.5 and 23.7 Mg·ha−1) at WRF and KRF, respectively. There were no differences in fruit numbers per plot between treatments, but mean fruit weight was between 33% and 71% larger in GR than NG treatments. In 2016, GR (‘NH1320’ rootstock) and NG ‘Halona’ were compared at three transplantation dates, 12 and 21 May and 1 June, and with two irrigation frequencies, drip irrigation every 2 days (2-d Irr) or every 4 days (4-d Irr). NG plants exhibited symptoms of sudden wilt in early August compared with no symptoms on GR plants. Harvests of NG melons were 3 to 8 days earlier than GR plants for all three planting dates. The increase in yields of GR plants compared with NG plants for the 12 and 21 May and 1 June planting dates were, respectively, 131%, 123%, and 149% greater with the 2-day Irr, and 93%, 100%, and 78% greater with 4-d Irr. Irrigation frequency did not significantly affect fruit size or soluble solids content (SSC), whereas grafting increased both fruit number and fruit size but did not significantly affect SSC at all three planting dates.