Effect of different cultural patterns on the growth and herbicidal responses of rice and barnyardgrass.
The effect of different cultural patterns on the growth and herbicidal response of rice and barnyardgrass (Echinochloa crus-galli var. oryzicola) was studied under direct-seeded rice and early rice seedling conditions in Korea Republic. Under dry-seeded rice conditions the growth of rice and barnyardgrass was greatest at 3-cm seeding depth and 40% soil moisture, respectively. At 10 days after herbicide application, rice plant height was severely inhibited at 1-cm seeding depth and 50% soil moisture, and the degree of inhibition was greatest following the application of pendimethalin + molinate EC compared to butachlor EC. However, barnyardgrass plant height was severely reduced following herbicide treatment regardless of the seeding depth and soil moisture. The length of barnyardgrass mesocotyls and rice coleoptiles increased with an increase in seeding depth, and both were severely inhibited when herbicides were applied at the 1-cm seeding depth under dry-seeded rice conditions. The dry weight of rice at different leaching times after herbicide application decreased as the leaching time was delayed. However, the growth of barnyardgrass was severely inhibited regardless of the leaching time. The phytotoxicity of herbicides to rice grown under early rice seedling conditions decreased with an increase in transplanting depth and delay in the time of application of herbicides.