A. Vanderwerf et al., COMPONENTS OF RELATIVE GROWTH-RATE AND NITROGEN PRODUCTIVITY OF BRUSSELS-SPROUTS AND LEEKS GROWN AT 2 WIDELY DIFFERING LIGHT INTENSITIES, Netherlands journal of agricultural science, 44(1), 1996, pp. 21-29
Early in the season, Brussels sprouts have a higher rate of biomass pr
oduction than leeks at recommended fertilizer (nitrogen) application r
ates. Furthermore, they have a considerably higher annual biomass prod
uction and a higher annual biomass production per unit of nitrogen tak
en up. In this paper we explore and discuss the possible explanations
for these field observations, using information obtained from growth c
hamber studies and the literature. Young vegetative plants of Brussels
sprouts and leeks were grown in a growth chamber at a light intensity
of 550 mu mol m(-2) s(-1) and at a light intensity which was 20% of t
hat of the high-light treatment. At both light treatments, Brussels sp
routs had an approximately 90% higher relative growth rate than leeks.
At both light treatments the higher relative growth rate of Brussels
sprouts was mainly explained by its higher leaf area ratio. Only minor
differences in the physiological component, the net assimilation rate
, between the two species within a light treatment were observed. The
higher leaf area ratio of Brussels sprouts was mainly explained by its
higher specific leaf area. Brussels sprouts had a higher rate of biom
ass production pet. unit of internal nitrogen (nitrogen productivity)
than leeks. This was mainly explained by a higher allocation of nitrog
en to leaves and a higher rate of biomass production per unit leaf nit
rogen. We suggest that the higher biomass production per unit of nitro
gen taken up of Brussels sprouts compared to that of leeks as observed
in the field is explained by its higher nitrogen productivity. The re
sults obtained from the growth chamber studies are discussed in relati
on with field experiments and data from the literature.