• N Balakrishnan Nair

      Articles written in Proceedings – Plant Sciences

    • Growth rates ofSalvinia molesta Mitchell with special reference to salinity

      O Divakaran M Arunachalam N Balakrishnan Nair

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      InSalvinia molesta Mitchell growth rate was uniform among the various size groups except in the proliferating floating stage in which it was faster. An average increase of about 25% weight occurred during a period of 5 days under laboratory condition. In general fresh set of leaves developed at an average interval of 4·5 days but this period may vary under different environmental conditions. In low salinities the growth of the fern showed retardation while in higher salinities it underwent complete destruction. Salinities above 7‰ was harmful for the weed while it completely withered in salinities 11‰ and above. Minimum period required for the total withering of the weed in salinities 34‰ and 11‰ were 30 min and 20 h respectively. These results are of value in the effective control of the weed by flushing them into brackish water lakes during monsoon.

    • Studies on the ecology ofSalvinia molesta Mitchell: B. Faunal associates of lentic and lotie habitats

      M Arunachalam O Divakaran N Balakrishnan Nair

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      Seasonal fluctuations of the fauna associated with the water fern,Salvinia molesta growing in a lotic habitat and the fluctuations during the three stages of the fern’s growth in a lentic habitat were studied. As many as 66 species belonging to six phyla were recorded, the major components being crustaceans, insect larvae and gastropods. The density of the fauna of the lotic habitat varied between 1267–7663/kg ofSalvinia, and thatof Salvinia of floating stage, intermediate stage and grown up stage (overcrowded) of the lentic habitat were 9610, 8860, 108 respectively/kg. Prolonged overcrowding ofSalvinia resulted in a sharp decline of the associated fauna.

    • Studies on the life cycle and ecology ofSalvinia molesta Mitchell

      O Divakaran M Arunachalam T Murugan N Balakrishnan Nair

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      Salvinia molesta Mitchell propagates vegetatively by proliferation. Spores are nonviable. Mechanical disturbance enhances the rate of proliferation. The rates of proliferation within 30 days are 1: 8 in agitated media and 1: 1 · 6 in intact media under laboratory conditions. While the frequency of addition of fresh set of leaves ranged between 3–18 days in the natural habitat it was between 3–9 days under the laboratory condition. Crowding ofSalvinia is a prerequisite for the cessation of proliferation and initiation of the final ‘grown up stage’.Salvinia of ‘floating stage’, ‘intermediate stage’ and ‘grown up stage’ have different density ranges such as 765–986, 942–1280, and 65–345/m2 and biomass ranges of 18–25, 50–70 and 340–375 g dry wt./m2 respectively under natural conditions.

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