EFFECT ROW SPACING AND HERBICIDES ON GROWTH AND YIELD OF MAIZE (ZEA MAYS L.) AND ASSOCIATED WEEDS

Abstract

A field experiment was conducted at the research station of the Department of Field Crops, College of Agriculture, University of Diyala, during the spring season of 2025 to evaluate the effect of row spacing and some recently introduced herbicides in Iraq on the growth and yield of yellow corn and its associated weeds. a split-plot arrangement within a Randomized Complete Block Design (RCBD) with three replicates was used. The main treatments included plant densities of 80,000, 66,600, and 57,100 plants ha⁻¹, while the sub-treatments included weed-control treatments: weed-free, weedy check, and herbicide treatments Arrivo, Abel, and Ramses. The results showed the superiority of the plant density 80,000 plants ha⁻¹ in most studied traits compared with 66,600 and 57,100 plants ha⁻¹. It produced the lowest weed density at harvest and recorded the highest inhibition percentage and highest leaf area index (8.61 plants m⁻², 67.88%, and 3.464 cm², respectively), as well as the highest crop growth rate and biological yield. The plant density 57,100 plants ha⁻¹ was superior in number of grains per ear and oil percentage, recording 525.66 grains and 4.64%, respectively. Regarding weed-control treatments, the Ramses herbicide excelled in weed inhibition percentage, leaf area index , and crop growth rate, which resulted in the highest grain yield (19.80 t ha⁻¹).The Arrivo herbicide achieved the lowest weed density (6.23 plants ha⁻¹) at the high density of 80,000 plants ha⁻¹.The Abel herbicide with the density 57,100 plants ha⁻¹ produced the highest number of grains per ear (549.60 kernels), while Ramses at the same density produced the highest oil percentage (4.76%).The interaction between plant density and weed-control treatments had a significant effect on most studied traits. The results indicate that selecting an appropriate plant density with an effective herbicide plays an important role in achieving optimal crop growth, increasing yield, and improving quality through successful weed suppression and reduced competition, thereby providing greater economic return.