Original Research

The development from kinetic coefficients of a predictive model for the growth of Eichhomia crassipes in the field. I. Generating kinetic coefficients for the model in greenhouse culture

C. F. Musil, C. M. Breen
Bothalia | Vol 15, No 3/4 | a1834 | DOI: https://doi.org/10.4102/abc.v15i3/4.1834 | © 1984 C. F. Musil, C. M. Breen | This work is licensed under CC Attribution 4.0
Submitted: 05 December 1984 | Published: 06 December 1984

About the author(s)

C. F. Musil, Botanical Research Institute, Department of Agriculture & Water Supply
C. M. Breen, Botany Department . University of Natal,

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Abstract

The kinetics of N- and P- limited growth of Eichhornia crassipes (Mart .) Solms were investigated in greenhouse culture with the object of developing a model for predicting population sizes, yields, growth rates and frequencies and amounts of harvest, under varying conditions of nutrient loading and climate, to control both nutrient inputs and excessive growth in eutrophied aquatic systems. The kinetic coefficients, maximum specific growth rate (Umax), half saturation coefficient (Ks) and yield coefficient (Yc) were measured under N and P limitation in replicated batch culture experiments. Umax values and Ks concentrations derived under N limitation ranged from 5,37 to 8,86% d + and from 400 to 1 506 µg  N ℓ1respectively. Those derived under P limitation ranged from 4,51 to 10,89% d 1 and from 41 to 162 fig P ℓ1 respectively. Yc values (fresh mass basis) determined ranged from 1 660 to 1 981 (87 to 98 dry mass basis) for N and from 16 431 to 18 671 (867 to 980 dry mass basis) for P. The reciprocals of Yc values (dry mass basis), expressed as percentages, adequately estimated the minimum limiting concentrations of N and P {% dry mass) in the plant tissues. Kinetic coefficients determined are compared with those reported for algae. The experimental method used and results obtained are critically assessed.


Keywords

<i>Eichhornia crassipes</i>; growth kinetics; model development

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