EFFECT OF SEEDING RATES AND HERBICIDES ON GROWTH OF COMPANION WEEDS IN RICE FIELDS

Abstract

A field trial was carried out at Mishkab Rice Research Station, AL-Najaf governorate during the summer season of 2008 and 2009 to investigate the effects of seeding rates (120,140,160 and 180 kg.ha-1) and herbicides (oxadiazon and propanil) on growth of weeds and rice crop. A factorial experiment was carried out according to RCBD design with four replications . The seeding rate 180 kg.ha-1 gave lowest number of weeds after 30,60 and 90 days from date of sowing in both seasons (8.9, 15.5 and 23.2 plant.m-2 in first season and 7.4,15.2 and 24.2 plant.m-2) in second season, respectively. It also reduced dry weight of these plants by 35.6% and 10.4% in both seasons respectively. Therefore it gave highest of plant at both seasons, 87.9 and 83.3 cm respectively and high value of biological yield were 17.9 and 17.5 ton.ha-1 respectively at both seasons. Oxadiazon caused reduced number of weeds at stages 30, 60 and 90 days from plant-sowing at both seasons ( 1.7 , 2.1 , 12.1 , 11.8 , 25.5 and 24.1 plant.m-2 ) and also reduced the dry weight of these plants by 84% at both seasons. Therefore it gave higher biological yield (17.25 and 16.77 t.ha-1 respectively) at both seasons. Oxadiazon with 180 kg.ha-1 gave lowest dry weight of weeds at both seasons 25.0 and 23.6 gm.m-2 and superior biological yield 18.62 and 17.28 t.ha-1 respectively at both seasons. From these results we have seen that seeding rates and herbicides were working together against weeds and gave positive response to most characters of rice as grain yield.