TITLE:
Seeds as a Source of Carbon, Nitrogen, and Phosphorus for Seedling Establishment in Temperate Regions: A Synthesis
AUTHORS:
Byron B. Lamont, Philip K. Groom
KEYWORDS:
Cotyledons; Drought-Avoidance; Nutrient Transport; Photosynthesis; Root Elongation; Seed Mass; Seed Nutrient Content; Seedling Growth
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.4 No.5A,
May
30,
2013
ABSTRACT: Seeds are a
source of organic (carbon, C) and mineral (nitrogen, N and phosphorus, P)
nutrients for the growing seedling. There is much information on
seed mass and N and P contents, and the relationship between these and seedling
mass. Within the world’s temperate regions, these collectively show that N and
P concentrations remain constant or rise with increase in seed mass and that
seeds are larger and more nutrient-enriched in poorer soils. Seed N and P were
more important than seed C in accounting for seedling mass in 85% of studies we
assessed. In nutrient- and water-limited environments that are not
light-limited, large seeds routinely provision the seedling with N and P that
enhance C-fixation and thus general growth in the first wet season.
This system is so efficient that growth response to soil nutrients may be
negligible in first-year seedlings arising from seeds > 15 mg mass, N
content > 5 mg and P content > 1.6 mg. The elongating
taproot system absorbs nutrients and maintains water uptake as soil water
retreats, enhancing the chances of survival in the first dry season. We outline
an interpretative scenario for the special role of large seeds (>15 mg) in nutrient-
and water-limited environments that recognizes the critical role of N and P for
photosynthesis in ensuring sufficient C-supply to the rapidly descending roots
for effective drought-avoidance by the young plant.