Effects of Season and Cultivar Selection On External Maturity Indicators In Personal-Size Seedless Watermelons

Personal-sized watermelons (Citrullus linatus) are frequently harvested before or after sufficient ripeness has been achieved.  Traditional methods of determining commercial maturity at harvest have often proven unreliable when employed across the spectrum of commercially available cultivars.  The current 2-year study (2006-2008) examined the effects of season and cultivar selection on two external ripeness indicators (tendril senescence and groundspot color) in predicting maturity in personal-size watermelons.  Personal-size watermelon cultivars ‘Valdoria’ and ‘Vanessa’ were harvested at 20, 30, 40, 50 days post anthesis.  At each harvest, number of proximal senescent tendrils and groundspot color values (Hunter L a* and b*) were determined for each cultivar.  Sugar: acid ratio was analyzed as a predictor of maturity at harvest.  Correlations between sugar: acid ratio and both external indicators were determined.  Season significantly effected groundspot Hunter a* (p≤ 0.04) values and number of senescent tendrils (p≤ 0.001).  In season two, there was a linear relationship between groundspot Hunter a* and sugar: acid ratio (p≤ 0.0008).  Senescent tendril number was linearly related to sugar: acid ratio in season one (p≤ 0.0001) and two (p≤ 0.0004).  Cultivar selection did not affect groundspot color or senescent tendril number.  Groundspot Hunter b* and Hunter L did not sufficiently predict sugar: acid ratio.  The current study suggests that the degree of success in correlating tendril senescence and groundspot color with sugar: acid ratio is dependent on season.  Further studies are needed to provide accurate predictors of maturity at harvest.