Earliness in F1hybrid muskmelons and their parent varieties

Abstract

The present report is a study of earliness of certain F1 hybrid muskmelons and their parent varieties as measured by the time from planting to first pistillate flower and to first ripe fruit. The plants were studied in randomized blocks in different environments provided by different planting dates, locations, and cultural methods. The data were converted into logarithms and analyzed by the analysis of variance. The environmental effects encountered were greater than the genetic effects in determining the length of life cycle of the muskmelons in the different plantings. The plants grew faster in summer than in winter and early spring. Most of the nine parent varieties and eleven variety hybrids performed similarly in all of the five plantings. The parent varieties could be grouped into five significantly different earliness classes on the basis of the average lengths of their total growth periods in all five plantings. Some varieties, such as the Conomon, performed similarly in both growth periods. Others, like the PMR No.5, were early flowering and slow ripening; or, like the Kelly Sweet, were late flowering and fast ripening. The Melogold variety was more variable in different environments than were the other varieties. Five of the F1 variety hybrids were like the averages of their respective parents in length of period from planting to first ripe fruit. Three were significantly earlier than the averages of their respective parents; one was significantly later. Only two of the hybrids were significantly earlier than their respective early parents in total growth period. The F1 hybrids exhibited responses that ranged from no dominance to apparent heterosis for early flowering, slow ripening, and short total growth. Partitioning the total growth period demonstrated that a hybrid could exhibit apparent heterosis for early maturity without exhibiting heterosis for either early flowering or early ripening. Such apparent heterosis probably resulted from dominance interactions rather than from heterozygosity per se.