TITTONELL P.A., DE GRAZIA J., CHIESA A.
Abstract
To evaluate the effect of N fertilization and plant population
on yield, shoot nitrate and dry matter concentration, a factorial trial combining
three levels of N (0, 75, and 150 kg N/ha) with two plant stand densities (33
and 50 plants/m2) was conducted. Grand Rapids leafy lettuce cultivar was sown
in the spring. Yield, fresh and dry weight of marketable plants, shoots dry
matter and NO3-N content were measured. Water content in shoot biomass and NO3-N
accumulation in leaf tissues increased with N fertilization, but no effect of
stand density was observed. Maximum NO3-N concentration occurred with 150 kg
N/ha at 33 plant/m2 (1768 ppm fresh weight basis) whereas the minimum (680 ppm
fresh weight basis) was observed at the lowest N and stand levels. Fresh weight
of marketable plants decreased 18.96 % with increased plant stand, but was improved
with N fertilization, independently of the doses employed.
Keywords:
Lactuca sativa L., N fertilization, plant population, growth,
nitrate