1984 Volume 53 Issue 1 Pages 30-37
Volume estimation was made on a cucumber fruit as attached to vine.‘Fruit volume index (FVI)’was calculated by FVI=l×(a12+a22+a32), where l is the fruit length and a1, a2 and a3 are the respective girths at 3 positions along the fruit length.
FVI had high correlations with volume (r>0.999), fresh weight (r>0.999) and dry weight (r>0.99) of a fruit. FVI gave estimation of the volume, fresh weight and dry weight of a fruit with errors of 3%, 3% and 0.2g, respectively. This method enabled us to determine the growth rate of a fruit even at intervals as short as 4 hours with sufficient accuracy.
The growth curve of a cucumber fruit was single sigmoidal. A Gompertz curve, which was obtained by using data at the growth stages from 1 to 80% final fruit volume, fitted well over the whole growth period for cv.‘Tokiwa Hikari 3 Go A Gata’, but not for cv.‘Kurume Ochiai H Gata’. For neither cultivar, a logistic curve showed better fitness to the whole period of fruit growth than a Gompertz curve did. RGR of a fruit was highest when it was 9 to 20cm long, followed by a rapid decrease.
RGR of a fruit with the length shorter than 20cm showed clearly a diurnal change with a maximum value between 12:00 and 20:00. Daily means of RGR were higher on fine days than on cloudy days. RGR was higher in spring than in autumn.
Fruits of cvs.‘Tokiwa Hikari 3 Go A Gata’and‘Kurume Ochiai H Gata’were different in their size at the matured stage as well as in their time to reach that stage. However, they were not different in RGR before they reached 20cm long.