Ecological and ethnobotanical values of weeds found in the spring rice fields in Chitwan, Nepal

Abstract

Background: The reliance of human beings on plants for different purposes such as medicine, fodder, fuel, and shelter is fading away, primarily, due to increasing dominance of market economy globally in the recent decades. Ethnobotanical study, especially that of weeds, is playing a crucial role in establishing the relationship between weeds and people, thereby documenting important uses of such weeds. Chitwan, located in the central part of Terai, is considered the grain basket of Nepal. The district is relatively advanced in agriculture, with higher agricultural productivity than that in most of the country. Spring rice cultivation is prevalent in the area. Weed infestation is one of the severe problems adversely affecting rice cultivation. These weeds have different ethnobotanical values for indigenous ethnic groups as well as residents.

Methods: Ecological survey was carried out in four distinct sites: the rice fields of the Institute of Agriculture and Animal Science, Gitanagar, Champanagar, and Ujjalnagar of Chitwan, Nepal. Weeds were collected from three randomly placed one-square-meter quadrats in each rice field. The ethnobotanical uses of the weeds were explored via key informant surveys with traditional healers from Tharu and Darai ethnic groups and the Brahmin caste in Mangalpur, Gitanagar, Champanagar, and Ujjalnagar.

Results: Weed flora of 53 species belonging to 43 genera and 22 families were reported in the spring rice fields. Cyperaceae (twelve species), Compositae (five species), Fabaceae (four species), Linderniaceae (four species), Plantaginaceae (four species), Poaceae (four species), and Amaranthaceae (three species) were the families with the largest representation, accounting for approximately 68% of all weeds. The most common weeds were Spirodela polyrrhiza (L.) Schleid., Cyperus difformis L., Azolla Lam., Lindernia procumbens (Krock.) Philcox, Mecardonia procumbens (Mill.) Small, and Fimbristylis quinquangularis (Vahl) Kunth. These weeds also possess different ethnobotanical values, the most common being medicinal and fodder values.

Conclusions: This study reveals the significance of weeds as medicine along with their medicinal values. People still rely on such plants as a primary healing resource. In addition, weeds can be used as fodder for livestock and have other important uses in local daily life. Hence, there is a dire need to spread awareness regarding ethnobotanical uses of weeds found in spring rice fields in Chitwan. This can possibly contribute to the sustainable uses of weeds, rather than grossly eliminating them from the field, which poses a threat to their extinction.

Keywords: Fodder, Important Value Index, Medicine, Summed Dominance Ratio, Tharu