Pt. Wismer et al., BENZYLADENINE AFFECTS CELL-DIVISION AND CELL-SIZE DURING APPLE FRUIT THINNING, Journal of the American Society for Horticultural Science, 120(5), 1995, pp. 802-807
Benzyladenine (BA), carbaryl (CB), daminozide (DM), and naphthaleneace
tic acid (NAA) were applied postbloom as fruitlet thinning agents to m
ature 'Empire' apple (Malus domestica Borkh.) trees. BA, NAA, and CB r
educed fruit set and yield per tree, and increased fruit size, percent
dry weight, soluble solids content and return bloom. Fruit size was r
educed, return bloom, length : diameter ratio and flesh firmness were
increased, and fruit set and yield unaltered by DM. Although fruit set
and yield were similar for BA, NAA, and CB, BA treated fruit were lar
ger, indicating that BA increased fruit size beyond the effect attribu
table to chemical thinning alone, BA increased the rate of cell layer
formation in the fruit cortex, indicating that BA stimulated cortical
cell division, NAA, CB and DM had no effect on cell division rate, Mea
n cortical cell diameter at harvest was increased by NAA and CB and re
duced by DM. Cell diameter at harvest in BA-treated fruit was similar
to the control, These data support the hypothesis that BA-induced frui
t size increase in 'Empire' apple results from greater numbers of cell
s in the fruit cortex, whereas the fruit size increase due to NAA or C
B is a consequence of larger cell size. Chemical names used: N-(phenyl
methyl)-1H-purine-6 amine [benzyladenine (BA)]; 1-napthaleneacetic aci
d (NAA); 1-naphthalenyl methylcarbamate [carbaryl(CB)]; butanedioic ac
id mono (2,2-dimethyl hydrazide) [daminozide (DM)].