The ecological study of the weed flora of some of the hill areas of Meghalaya and their chemical control

Abstract

The present investigation was undertaken with a design to study the ecology of weeds growing in cultivated and agricultural area of high altitude (1390 metres) and heavy rainfed area (annual rainfall 410.824 cms.). The survey was confined within an area around Jowai town, the headquarter of Jaintia Hill District, Meghalaya which comprised of five villages, viz., Demthring, Pynthorlangtein, Muphlang, Mustem and Iongnoh and covered an area of about 50 sq. km. The cultivated area included four crops, viz., paddy, maize potato and sweet potato fields. The survey continued for a period of three years (1973, 1974 and 1975). The ecological studies of weed-flora comprised the consideration of edaphic factors, floristic composition, phenology, weed phytosociology which includes studies on density, frequency percentage, abundance and Importance Value Index (IVI) of weed species followed by the determination of Dominance Index, Diversity Index, Similarity and Dissimilarity Index of difference crop-weed communities, the germination and reproductive capacity of a few common and dominant weed species and finally, the control of weeds by the application of weedicides in different crop fields. The experimental operation involved a survey of paddy fields measuring a total area of 47,60,000 sq.m. The plot size and quadrat size were 25 sq. m. and 5 sq. m. respectively. Altogether 1904 plots and 9520 quadrats were thrown for 1 per cent survey of total area. For maize fields, a total area of 6,60,000 sq.m. was taken into consideration and 1 per cent survey of the total area gave 246 plots and 1320 quadrats using same plot size and quadrat size as in paddy field. For potato field, a total area of 3,64,000 sq.m. was surveyed and 1 per cent survey of the total area gave 146 plots and 730 quadrats. Finally, sweet potato field comprised of an area of 4,20,000 sq.m. was surveyed and a survey of 1 per cent of the total area gave 168 plots and 840 quadrats, using the same plot size and quadrats size as above. The selection of plots for...