© 1997 Heron Publishing—Victoria, Canada
Effects of foliar potassium concentration on morphology, ultrastructure and polyamine concentrations of Scots pine needles
Anne Jokela (1), Tytti Sarjala (2), Seppo Kaunisto (2) and Satu Huttunen (1)
1. University of Oulu, Department of Biology, Botany, P.O. Box 333, FIN-90571 Oulu, Finland / 2. The Finnish Forest Research Institute, Parkano Research Station, FIN-39700 Parkano, Finland / Received November 27, 1996
Summary
We examined the effects of three foliar potassium concentrations (high, intermediate and low) on the morphology, ultrastructure
and polyamine concentrations of current-year and 1- and 2-year-old needles of 30-year-old Scots pine (Pinus sylvestris L.) trees. Foliar K concentration had only a slight effect on needle morphology. The sclerenchyma cell walls were thinner,
the xylem area was larger, and the resin ducts were smaller in needles with a low K concentration than in needles with a high
or intermediate K concentration. In addition, the bundle sheath cells were collapsed in needles having a low K concentration.
The secondary growth of phloem tissue and the mesophyll area were greater in needles with a high or intermediate K concentration
than in needles with a low K concentration, possibly indicating greater production of photoassimilates in these trees. At
the ultrastructural level, mesophyll cells with enlarged central vacuoles and small vacuoles containing electron-dense material
were common in needles having a low K concentration. Enlargement of the central vacuole coincided with an exponential increase
in putrescine concentration in needles with a low K concentration, suggesting that the central vacuole may function as a storage
site for putrescine.
Keywords:
needle morphology, Pinus sylvestris, potassium deficiency, putrescine.
