Abstract
"Galia" muskmelons were originally developed for open-field cultivation in the desert regions of Israel. Nitrogen fertilization recommendations for 'Galia' production include altering N concentrations through four stages of plant growth: seeding to flowering, flowering to fruit set, fruit development, and fruit ripening through final harvest. It is unknown if those N recommendations for field production would be appropriate for 'Galia' muskmelon grown hydroponically in soilless media. In the present work, "Galia" muskmelons were grown in a passively ventilated greenhouse during three seasons in Gainesville, Florida using polyethylene-bag perlite culture. Nitrogen concentrations were applied with every irrigation at 80, 120, 160, 200, and 240 mg·L[sup-]. An alternating N (ALT-N) treatment that followed the four growth stages was also included (120-160-200-120 mg·L[sup-]). In all three seasons, there were no differences among the N treatments for average fruit weights or soluble solids content. In spring 2001, plants receiving N in relation to their growth stage produced the greatest number of fruit per plant and per square meter at 6.4 and 15.5 fruits, respectively. In fall 2001, plants receiving 80 and 120 mg·L[sup-] N produced significantly lower fruit numbers than those produced by all other N treatments. There was no difference among plants receiving 160, 200, 240 mg·L[sup-], and the ALT-N treatment for fruit number per plant, each averaging 4.8 fruits. Petiole-sap NO[sub3]-N concentrations during spring and fall 2001 suggested that optimal yields can be achieved if at least 3000 mg·L[sup-] NO[sub3]-N was maintained through fruit maturation. When petiole-sap concentrations were less than 2500 mg·L[sup-], as in the case of plants receiving 80 or 120 mg·L[sup-] N, significantly lower yields were obtained.
