Anjana Dewanji

Chemical composition of two semi-aquatic plants for food use

The seasonal variation in the nutrient composition ofEnhydra fluctuans andMarsilea quadrifolia, two edible semi-aquatic plants, was studied in order to promote their consumption as green leafy vegetables. Both plants had a high crude protein content throughout all harvesting seasons.Enhydra fluctuans had a low ash content and was a good source of β-carotene (3.7 to 4.2 mg/100 g on a fresh weight basis).Marsilea quadrifolia exhibited wide fluctuations between seasons and was not very promising in nutrient composition when compared to other commonly used green leafy vegetables.

The ability of aquatic macrophytes to maintain water clarity in two tropical ponds

The ability of aquatic macrophytes to maintain water clarity was investigated in two tropical ponds [1999–2001]. Low chlorophyll‐a concentration (0.2–3.5 mg/m3) was observed throughout the study period, which reflected the absence of any algal bloom. At a high coverage (≥ 90%), the ability of Vallisneria spiralis to maintain Secchi disk transparency (> 2 m) extended to the deepest point (3.5–4.4 m) even at high Kjeldahl nitrogen (1.2–29.8 mg/l) and total phosphorus levels (0.2–1.2 mg/l).

Extractability and nutritional value of leaf protein from tropical aquatic plants

In a study conducted on the extraction of protein from the leaves of 30 freshwater aquatic plants, the highest standing crop fresh yield was found inTypha latifolia (2650g/m2). The Bio-Medical Data Processing (BMDP)K-means clustering program withK=2 showed that 11 of the 30 plants had a high protein nitrogen extractability as well as a high nitrogen content of the extracted protein. Among these, leaf protein fromAllmania nodiflora had the highest content of crude protein (62.7%) and β-carotene (782.4 μg/g). Leaf protein prepared fromHygrophila spinosa, Ottelia alismoides andPolygonum barbatum had low in-vitro digestibility. The levels of alkaloids and polyphenols were lower in the extracted protein compared to that present in the original leaf sample.

Impact Assessment on Floral Composition and Spread Potential of Mikania micrantha H.B.K. in an Urban Scenario

The present study is concerned with one of the top ten worst weeds of the world, Mikania micrantha H.B.K., and its growth in a rapidly urbanizing city, Kolkata. The two primary objectives were to assess the impact of this invasive plant on floral diversity as well as its potential for spread into new areas. A quadrat based assessment was conducted to estimate the impact of M. micrantha on floral diversity at 69 terrestrial sites which were subsequently grouped on the basis of the infestation size of M. micrantha. A significant reduction in the number of native species with increasing infestation size of M. micrantha was noted. The clay component of soil texture along major roadsides, as found in this study, significantly favoured extra-large growth of M. micrantha in contrast to the sandy loam soil type which generally favours their luxuriant growth in forest areas. The ‘distance from road network’ analysis revealed that most of the large infestations were along highways and that the satellite infestations of M. micrantha did not readily progress into larger infestations along minor roads. Application of remote sensing technology identified the vulnerability of the ‘sparse vegetation’ land use class for future spread of infestation. Although majority of the infested sites comprised of satellite populations with very few extra-large patches, the rapid rate of urbanization within cities highlights the need for ‘early detection and rapid response’ to prevent large scale invasion in future.