S. Iivonen et al., Seasonal root growth of Scots pine seedlings in relation to shoot phenology, carbohydrate status, and nutrient supply, CAN J FORES, 31(9), 2001, pp. 1569-1578
Citations number
42
Categorie Soggetti
Plant Sciences
Journal title
CANADIAN JOURNAL OF FOREST RESEARCH-REVUE CANADIENNE DE RECHERCHE FORESTIERE
To ascertain whether the growth rhythm of roots differs from that of the sh
oot, the seasonal pattern of dry mass allocation was determined in 1-year-o
ld Scots pine (Pinus sylvestris L.) seedlings. Gas exchange, chlorophyll fl
uorescence, and the dynamics of starch and soluble sugars were examined to
understand the role of stored carbon and that of current photosynthates in
meeting the sink demand of plant organs. In this growth-chamber experiment,
hydroponic cultures supplied the seedlings with low (0.25 mM N) or high (2
.5 mM N) nutrient level. The climatic conditions in the chamber simulated t
he weather conditions from May to mid-October in southern Finland. Root gro
wth was most intense at the end of the growing season, at which time shoot
growth slowed down. Nutrient level did not affect the growth rhythm of the
roots, but the total production of root biomass was favoured by high level
of nutrients. The response of root growth to root zone temperature (RZT) wa
s not the same over the growing season, indicating that the sensitivity of
root growth to RZT depends on the growth phase of the seedling. The growth
rhythm of the roots is probably regulated by several internal and external
factors and their interactions, including RZT and availability of photosynt
hates.