Planta Daninha (2005) 23, 359-362

F.T. Carvalho, E.D. Velini, A.L. Cavenaghi, E. Negrisoli and R.M. Castro (2005)
Influência da turbidez da água do rio Tietê na ocorrência de plantas aquáticas
[Influence of Rio Tiete water turbidity on the occurrence of aquatic plants]
Planta Daninha 23 (2), 359-362
Abstract: Aquatic plants are studied as an effect of pollution unbalance and/or river flooding. The excessive amount of plants,as a consequence of such unbalance, hinders navigation and electric power production. The objective of this work was to identify the main aquatic plants of the Tietê River and to relate them with water turbidity of the different reservoirs. All the foci of aquatic immersed, floating and submerged vegetation in each reservoir were evaluated in all their extension. Those species presenting a dominant character were considered important.The reservoirs were found to present aquatic plant problems with the quality of infestation varying among the reservoirs. The following species were considered to be dominant: Brachiaria mutica, Brachiaria subquadripara, Eichhornia crassipes, Egeria densa, Egeria najas, Typha angustifolia and Enidra sessilis.There was a tendency for a greater occurrence of floating and submerged (marginal) plants in the reservoirs with greater turbidity and for a larger occurrence of submerged plants in reservoirs with less turbidity. For the two Brachiaria it was observed that the frequency of the species increased with the increase of turbidity up to the limit of 34.93 NTU. E. crassipes occurred with high frequency indexes (above 50%) in all the Tietê River reservoirs, independent of the characteristic of the water. For Egeria, frequency increased gradually with reduced turbidity and T. angustifolia did not present a relationship with the studied index. The species E. sessilis was found to be rather dependent on the quality of the water,its frequency increasing with increased turbidity.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
(original language: Portuguese)
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Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Pontederia crassipes (weed)		Brazil (south)
	Egeria densa (weed)		Brazil (south)
	Urochloa mutica (weed)		Brazil (south)
	Typha angustifolia (weed)		Brazil (south)
	Urochloa distachya (weed)		Brazil (south)
	Egeria najas (weed)		Brazil (south)