N. Gruda et al., N-immobilization of wood fiber substrates in the production of tomato transplants (Lycopersicon lycopersicum (L.) Karst. ex Farw.), J APPL BOT, 74(1-2), 2000, pp. 32-37
N-immobilization of wood fiber substrates during production of vegetable tr
ansplants was studied in greenhouse and under phytotron conditions.
Tomato transplants were grown on white peat, unimpregnated and impregnated
wood fiber with three N-levels respectively N-immobilization was calculated
on the basis of N-balance including N-uptake by plants and residual minera
l N in the substrates. in addition, the influence on net photosynthesis rat
e was examined.
Higher N-immobilization was found by increasing of N-application rates. Net
-N-immobilization in impregnated wood fiber substrates was comparable to wh
ite peat with 100 mg N l(-1). Tomato transplants, cultivated on impregnated
wood fiber substrates, showed significantly higher growth compared to plan
ts cultivated in unimpregnated wood fibers.
With additional N-fertilization (level N3) the significance of N-immobiliza
tion in impregnated wood fiber substrates for the growth of tomato plants c
ould be neglected. However, general recommendations for the amount of ferti
lizer to be added are difficult, because of strongly varying contents of mi
neral nutrients in the different substrate loads. Nevertheless, it is neces
sary to supply wood fiber substrates with nutrient solutions or fertilizer
from the beginning of plant culture.
Substrates without plants, exposed to the same conditions showed the same t
endencies in N-immobilization, as substrates with plants.