Characterization of seasonal fruit growth of ‘Idared’ apple

Abstract

‘Idared’ fruit fresh weight (FW), dry weight (DW), relative growth rate (RGR), dry matter concentration (DMC), and percent cell division (CD) were regressed against days after full bloom (DAFB). Fruit FW and DW were accumulated linearly throughout most of the growing season. Fruit RGR and CD peaked about 20 DAFB, when 85% of the cells were in mitosis. CD then declined until about 50 DAFB, but a CD rate of about 10% continued until 103 DAFB. By 35 DAFB, fruitlet DMC decreased to half of its value at full bloom; it then increased for 20 days, before finally decreasing very slowly until the end of the season. Three stages of apple fruit growth are suggested.