EFFECTS OF NITROGEN CONCENTRATION, TEMPERATURE AND LIGHT-INTENSITY ON GROWTH AND NITROGEN UPTAKE OF YOUNG CHRYSANTHEMUM PLANTS GROWN HYDROPONICALLY

Influences of nitrate nitrogen levels in hydroponic culture solution, growth temperature, and natural light intensity on growth and nitrogen uptake by chrysanthemum cv. Otomezakura plants at the vegetative stage were investigated. Comparison among three temperature regimens revealed that plant growth at 20-degrees-C was better than that at 15-degrees or 30-degrees-C. At 20-degrees-C, no difference in growth in plants was detected between those supplied 100 or 200 ppm N. At 30-degrees-C, plants given 200 ppm N grew better than those supplied 100 ppm N. At 15-degrees-C, plants supplied with 100 ppm N absorbed the same amount of N as those grown at 20-degrees-C, whereas, plants given 200 ppm N took up more N than those supplied 100 ppm N. Under sufficient natural light intensity for normal growth, chrysanthemum plants grew equally well whether they were supplied with 100, 200 or 300 ppm N. Reducing natural light intensity 70% by shading decreased plant growth markedly at 100 ppm N. However, equally shaded plants supplied with 300 ppm N grew better than those given lower conc. of N. All other factors being equal, nitrogen uptake by plants was proportional to the nitrogen conc. in the nutrient solution.