Abstract

The present study compares ionic balance in 19 muskmelon cultivars grown under greenhouse conditions with the same system of fertilization-irrigation. Each cultivar was studied in 4 replications distributed in a random block design. In all 20 plants were sampled in each replication of each cultivar every 15 days throughout the reproductive cycle, and analyzed inmediately afterward. Highly significant differences were, noted for cations (C+) (Gold-King 304 meq/100g d.w., Canario 183 meq/100g d.w., anions (A-) (Cantaloupe 387 meq/100g d.w., Arava 272 meq/100g d.w.), and cations-anions balance (C+-A-) (Gold-King -6 meq/100g d.w., Rocher -157 meq/100g d.w., Canario -163 meq/100g d.w.), as well as for hydrogen ions (H+) forming capacity (Dorado and Gold-King 88 meq/100 g d.w., Gallicum, Rocher and Canario 0 meq/100g d.w.). Differences in OH- formation were also notable (Polidor 243 meq/100g d.w., Makdimon 120 meq/100g d.w.). Consequently, fruit production among the different cultivars varied widely. The findings suggest that the more complex the mechanism to be quantified is the greater the differences will be between cultivars. A considerable range of variation was found for cations, anions and cations-anions balance. Furthermore, leaf concentration of hydrogen ions and hydroxyl ions is known to be an identifying feature among different cultivars. The changes in foliar concentrations of cations, anions and cations-anions balance with plant age show the same trends in all cultivars, being conditioned by the size of the sink (fruit). The influence of physiological activity varies with leaf cations and anions levels.