Ethnobotanical studies of weed plants in rice field ecosystem

Tamilnadu is one of the leading states in rice production in India. Weeds are widely found and are tremendously grown everywhere on paddy fields. Ethnobotany have gained importance during recent years. Based on this, an ethnobotanical exploration has been carried to find out the medicinal values of weed plants growing in the paddy fields of Annamalai Nagar, Cuddalore district. The study reveals the importance of the weed plants associated with paddy fields, a total of 40 species of weeds belonging to 22 families has been recorded in meeting the multiple requirements of human beings.


INTRODUCTION
India is one among the major biodiversity rich countries of the world.Paddy (Oryza sativa L.) is a major food crop of the world and is cultivated widely in India.Ethnobotany is usually defined as anthropological approach to botany [1].Thus, 'Ethno' refers to people, culture, language, knowledge and practice and 'Botany' is the study of plants.Weeds are very common in all parts of Tamil Nadu, India, and mainly in agricultural fields like rice fields [2].Thus, the present study deals with ethnobotanical aspects of the major weeds of paddy fields in Tamilnadu.

Study area
Annamalai Nagar is a special grade panchayat town in cuddalore district of Tamilnadu.It is located at about 6 Km west of Bay of Bengal at 11° 24' North latitude and 79° 41' East longitude and at an altitude of +5.79 M above the Mean sea level (MSL).The climate is moderately warm with hot summer months.The mean maximum temperature ranges from 29.7°C to 38.3° C with a mean of 32.42°C while, the mean minimum temperature ranges from 21.1°C to 27.0° C with a mean of 24.1°C.The mean relative humidity is 73%.

Methodology
The ethnobotanical survey was conducted in the selected paddy fields of Annamalai Nagar region in cuddalore district of Tamilnadu during the year 2018.Observation on morphology of the weed and their habitat were recorded.The ethnobotanical research regarding the medicinal utility of the common weeds were collected with the help of field labours and local community.They had indigenous knowledge about the weed plants growing in the paddy fields.However, relevant literature was also consulted on the basis of interviews in local language.Standard procedure was adopted for preparing herbarium sheets.All collected specimens were critically examined in the Herbarium for proper identification.

RESULTS AND DISCUSSION
The ethnobotanical information in the study area about the use of weed plants in paddy fields of Annamalai Nagar region was well documented.All the major weeds are reported to have medicinal properties.The different parts of the plant that are used for medicinal purposes such as leaves, shoots, roots, seeds, fruits, flowers etc.These parts contain some medicinal value used to cure specific diseases.Their botanical features and medicinal potential are given in the table as follows.Based on the survey, there are 40 species of weeds belonging to 22 families were recorded (Table 1, Figure 1).The dominant family Amaranthaceae having 6 species, followed by Euphorbiaceae, Solanaceae and Poaceae having 4 species each, Cyperaceae having 3 spp, Asteraceae, Lamiaceae, having 2 spp each and the other families sharing 1 spp each.The collection of information obtained from the ethnobotanical survey was similar to the investigation done by Dhanam and Elayaraj [3] in paddy fields of Villupuram district.Ethnobotanical studies are helpful in revealing medicinal potential of underutilized plants especially in complicated and minor diseases [4].Many plants and their products recently used in industries were developed through the indigenous ethnobotanical knowledge.So, it is need of the time to enhance our ethnobotanical knowledge on weeds plants.

Arunesh, et al
Arunesh, et al But modernization resulted in decrease of ethnobotanical information and hence attempts are being made to make a permanent record on plants and their uses by Botanical Authorities of India [5].Thus in this pollution rich environment human beings are prone to diseased conditions easily and these ethnobotanical aspects are dealing it a readymade solution to solve those problems especially in rural regions.There is a need of the hour to investigate these studies further and explore more things.

Figure 1 :
Figure 1: Major weeds present in rice fields