WEED FLORA AND IMPORTANCE VALUE INDEX (IVI) OF THE WEEDS IN COTTON CROP FIELDS IN THE REGION OF KHANEWAL, PAKISTAN

A survey of weeds of cotton fields from five locations along the Khanewal Road; 1-Rawan, 2-Rango, 3-Kabirwala, 4-Chak8 Kasi, 5-Chak83/85 10-R was carried out during the year of 2010. Only the weed species in competition with cotton crops were studied; while 27 species from 19 genera and 11 families were identified impacting cotton crop fields of the region. Two important weeds including Cyperus rotundus L. and Echinochloa colona (L.) Link. were found with highest importance value index of 20.9 and 17.3, respectively having highest densities as well in the cotton fields. While in the water channels, two other species i.e. Marsilea minuta L. and Eclipta prostate L. were found in abundance. From all five locations, it was also estimated that crop sown on different dates i.e. April 15, 30, and May 15 and 30, 2010 have different broadleaved and narrow-leaved weeds density after the raining months of June and July in the year 2010. Density of broad-leaved weeds and narrow leaved weeds were highest in the treatments of cotton crop sown in May 30, 2010. Weed to plant height ratio was 0.51 for April 15 sown crop, 0.69 for April 30 sown crop, 0.77 for May 15 sown crop and 0.86 for May 30 sown crop. Late sown cotton crop had greater competition with weeds especially with narrow-leaved as compared to early sown crop due to higher moisture and damp conditions in the month of July.