Ar. Lawson et al., DEFOLIATION FREQUENCY AND GENOTYPE EFFECTS ON STOLON AND ROOT RESERVES IN WHITE CLOVER, Australian Journal of Agricultural Research, 49(6), 1998, pp. 983-988
The effect of defoliation frequency (1 or 3 defoliations over a 42-day
period) on the starch, water soluble carbohydrate (WSC), and nitrogen
contents of 3 white clover cultivars (Haifa, Irrigation, and S184) wa
s examined. The clover plants consisted of single stolons growing in a
sand/scoria mix in an unheated glasshouse and fertilised weekly with
a nitrogen-free solution. Starch concentrations ranged from 1.3% in fr
equently defoliated Haifa to 15.3% in infrequently defoliated S184 pla
nts. However, there was no interaction between cultivar and defoliatio
n frequency, with the starch concentration in S184 (11.2%) being twice
that in Irrigation (6.0%) and 3 times that in Haifa (3.8%). The starc
h concentration was also less with frequent (3.7%) than with infrequen
t (10.3%) defoliation. The starch was localised in the old stolen mate
rial (12.2%), with lower levels of starch in both the young stolen (6.
0%) and roots (4.0%). Furthermore, the cultivar and defoliation freque
ncy effects on the starch concentrations were most pronounced in the o
ld stolen. More frequent defoliation also resulted in a small reductio
n in the WSC and nitrogen concentrations in both the young and old sto
lons of Haifa, but not of Irrigation. It was concluded that although s
tarch reserves were the principal method of reserve storage in white c
lover, WSC and nitrogen reserves will form a relatively large fraction
of the reserve pool when starch reserves are depleted under condition
s such as frequent defoliation.