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Vegetative growth and productivity of Eichhornia azurea with special emphasis on leaf dynamics
Author(s) -
Ikusima Isao,
Gentil José Geraldo
Publication year - 1993
Publication title -
ecological research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.628
H-Index - 68
eISSN - 1440-1703
pISSN - 0912-3814
DOI - 10.1007/bf02347188
Subject(s) - shoot , dry season , dry matter , productivity , biomass (ecology) , biology , horticulture , agronomy , wet season , botany , ecology , economics , macroeconomics
The lifeform and the biological production of pure stands of Eichhornia azurea Kunth in three lakes in tropical Brazil were studied. The lifeform of E. azurea is termed ‘semi‐emergent’, because the plant has well developed trailing stems just under the water, and the aerial lamina emerges with the thick petiole. The density of shoot apices was 9.9, 17.2 and 17.1 m −2 in Lake Dom Helvecio, Lake Jacaré and Lake Carioca, respectively. The mean daily increment of the apical shoot biomass was between 1.8 and 4.8 g m −2 day −1 . The mean leaf life‐span in Lake Dom Helvecio, Lake Jacaré and Lake Carioca was estimated to be 78, 49 and 64 days in the wet season and 73, 70 and 73 days in the dry season, respectively. The stem life‐span was estimated to be about 28 months. Starch content in the current years' stem ranged from 24 to 118 mg g −1 dry matter with fluctuations, the amplitude of which decreased with age. The differences for most of the growth parameters, such as density of shoot apices, daily increment of biomass and leaf life‐span, between dry and wet season are smaller than those among the three lakes. Both the decrease in daily dry matter production and the increase in leaf life‐span occurred in order from Lake Dom Helvecio to Lake Jacaré and Lake Carioca. The low productivity of E. azurea is considered to be related to a low leaf area index, a long time interval for the emergence of new leaves, long leaf life‐span and a low capacity for branching.