Growth of chrysanthemum at low, relatively steady nutrient levels in a commercial-style substrate
Williams, K.A. | Nelson, P.V.
Nutrient solution with a molar ratio of 10 N : 1 P : 3 K was applied in scheduled intervals at rates of 0.5, 1, 4, or 20 mM N (NO3 + NH4) to Dendranthema X grandiflorum (Ramat.) Kitamura 'Sunny Mandalay' plants seven (7/day) or 14 times/day (14/day). These plants were compared to a 20 mM N control in which nutrient solution was applied when the soil moisture tension reached 30 kPa. Plants with 7/day had significant quadratic relationships for height, width, and dry weight, with the lowest responses at the low nutrient concentration. With 14/day, height and dry weight did not differ, although width did increase linearly with nutrient solution concentration. However, linear regression slopes for all three variables were much lower with 14/day than with 7/day. At midcrop in both experiments, significant regression curves indicated that the lower concentrations of nutrient solution resulted in lower tissue N and K levels; however, slopes of the linear regressions were lower with 14/day than with 7/day. With 7/day, the water content (percentage) of plants in the schedule-fertilized treatments was higher in plants receiving higher nutrient concentrations, as indicated by the significant linear and quadratic regression curves. With 14/day, the water content was linearly related to solution nutrient concentration, but with a lower slope than with 7/day. These three trends indicate that steady-state nutrition was more closely achieved in a commercial-style substrate with 14/day applications of nutrient solution. These results suggest that plant growth that meets commercial expectations can be achieved at lower soil solution nutrient concentrations than currently applied.
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