Comparison of Cell Size and Sugar Accumulation in Melons (Cucumis melo L.) Grown Early or Late in Summer

Abstract

Earl's Knight Natsukei No. 2 melons (Cucumis melo L.) were grown in a plastic film greenhouse after seeds were sown on June 25 (early sowing) or on July 15 (late sowing), 2002. Melons grown early tended to be higher in weight than those grown late. The average temperature throughout the growth period after the early sowing date was much higher than that after the late sowing date. In both rectangular parallelepipeds (7-mm long samples serially collected beginning at one end of the 10-mm wide strip removed from the 10-mm thick disk at the maximum transverse diameter of the fruit to the opposite end) and fruit, the cell size of melons grown early was greater at every stage of fruit development than that of melons grown late. Sucrose content on 30 and 50 DAA (days after anthesis) was greater after the early sowing than the late sowing. These results show that an increasing number of larger cells during early fruit development after early sowing brings active sucrose accumulation, resulting in high sucrose content in the fruit due to high temperature.