Studies on the cultivation and utilization of water hyacinth [Eichhornia crassipes (Mart.) Solms]: The growth analysis and solar energy efficiency of the community
1990
Okamoto, C. (Kyushu Tokai Univ., Choyo, Kumamoto (Japan). Faculty of Agriculture) | Kabata, K. | Shimizu, M. | Kikuchi, M.
In order to clarify a system of rational management on the cultivation of water hyacinth, the productivity, the nutritive value and the kinetics of the community were investigated at Ezu-lake in Kumamoto city. The highest standing crop on a dry matter and organic matter basis were 3.0 kg.m(-2) and 2.4 kg.m(-2), respectively. It was suggested that the growth of water hyacinth fitted to a logistic curve. The crop growth rate (CGR) and the leaf area index (LAI) increased with the progress of growth. And the maximum CGR of 27.4 g.m(-2).day(-1) and the maximum LAI of 11.9 were observed at the growth stage when the standing crop reached to the maximum. The CGR and the LAI had no decrease during the investigation period. On the other hand the net assimilation rate (NAR) showed the opposite tendency to these two factors. The maximum NAR of 6.9 g/m(-2).day(-1) occurred in the initial stage of growth, then, the NAR decreased with the progress of growth. The efficiency of solar energy utilization (Eu) showed a similar change to the CGR. When the CGR reached to the maximum rate, the Eu also reached to the maximum rate of 2.9%. In the initial stage of growth, there was little change for the proportion of petiole. Then, in proportion as the petiole increase, the CGR, the LAI and the Eu rose rapidly. Moreover, the high productivity continued with the continuation of the petiole's elongation growth. Changes of the nutritive value (organic matter, gross energy and crude protein content and in vitro dry matter digestibility) during the growth stage were relatively small. These results suggest that the harvest at the late stage of growth and decreasing the number of harvest are useful to manage the plant
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