Comparison of the Effectiveness of Selected Herbicides in Dry Seeded Rice under Fertilized and Non-Fertilized Conditions

Abstract

An examination of the effectiveness of a range of herbicide and herbicide combinations was made for fertilized and non-fertilized, rice direct seeded under both upland and lowland conditions. The studies were undertaken at the Ratchaburi Rice research Station during the 1980 - 1981 grwoing season. The herbicide treatments examined under upland conditions were oxadiazon, bifenox, benthiocarb + propanil, and propanil + 2,4+D; under lowlan dconditions the treatments were oxadizaon, bifenox, oxadiazon + 2,4-D and ioxynil + 2,4-D. The experimental layout was in the form of a split-plot design, the main plots being based on the fertilizer treatments; there were four replications.
Between the fertilized and non-fertilized treatments generally grain yield, dry matter yield of weeds and weed species did not vary significantly in either the upland or lowland conditions. However, the herbicides tended to be more phyutotoxic under the fertilized treatments than in the non-fertilized situation. In the non fertilized situation highest rice yield was obtained from the bifenox treatment under upland conditions and from the oxadiazon
2,4-D, and ioxynil + 2,4-D treatments under lowland conditions. In the fertilized treatment, propanil + 2,4-D gave the highest rice yield in the upland planting, and ioxynil + 2,4 -D in the lowland conditions.