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Physiological indicators of nitrogen response in a short rotation sycamore plantation. I. CO 2 assimilation, photosynthetic pigments and soluble carbohydrates
Author(s) -
Tschaplinski Timothy J.,
Norby Richard J.
Publication year - 1991
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1991.tb02911.x
Subject(s) - photosynthesis , human fertilization , growing season , nitrogen , biology , chlorophyll , photosynthetic pigment , botany , nitrogen deficiency , fertilizer , agronomy , photosynthetic capacity , nutrient , horticulture , chemistry , ecology , organic chemistry
American sycamore ( Platanus occidentalis L.) seedlings were grown in the field under different urea‐nitrogen fertilization regimes to identify physiological variables that characterize the growth response. Treatments included fertilization at the beginning of the growing season with 50, 150, 450 kg N ha −1 , fertilization 3 times each at 37.5 kg N ha −1 and unfertilized control. The greatest aboveground biomass accumulation (3× that of control) occurred in plots fertilized with 450 kg N ha −1 , but nearly as much growth occurred when 37.5 kg N ha −1 was added periodically. Photosynthesis, chlorophyll concentrations and growth increased rapidly after the midseason application of 37.5 kg N ha −1 but not after the late‐season application. Although nitrogen fertilization increased leaf area per plant, leaf nitrogen concentration did not differ between treatments. There was no evidence to indicate that fertilization extended the physiologically active season or increased susceptibility to drought or cold. Sycamore leaves accumulated sucrose and mannose in response to water stress in all treatments. Photosynthetic pigment concentrations and net photosynthetic rate were the most sensitive indicators of growth response to nitrogen fertilization in the first growing season. Careful timing (based on physiological indicators) of low level applications of nitrogen fertilizer can optimize growth.