Growth rates of glasshouse tomato fruit in relation to final size

The individual growth rates of the first five tomato fruits on 25 trusses of similar age within a crop grown in commercial glasshouse conditions were assessed from anthesis to ripening during April and May. Final size of fruit at ripening was proportional to the maximum rate of increase in fresh weight, about 40 d after anthesis, and related to the maximum rate of increase in diameter, between 15 and 20 d after anthesis, even though ripe fruit fresh weight varied from 20 g to over 100 g. On any one truss these fruit ripened within the same week, regardless of fruit size and prevailing growth rate. These findings suggest that final size was related to the peak fruit growth rate rather than the duration of development. A high growth rate late in development did not delay fruit ripening. The implications for recent continuous measurements of the diameter growth rate in young fruit are discussed.