EVALUATION OF THE PERFORMANCE OF DOUBLE CROSSES OF MAIZE UNDER PLANTING DATES SUITABLE FOR THE FALL SEASON IN THE MIDDLE REGION (SECONDRY COMPENNTS OF YIELD)

Abstract

In order to evaluate the performance of double-cross maize hybrids in planting dates suitable for fall growing season in the middle region of Iraq, a field experiment was conducted at the fields of the College of Agricultural Engineering Sciences - University of Baghdad - Jadriya for the fall season of 2022 using double-cross maize hybrids selected from fifteen double cross hybrid maize resulted from  crossing ten single hybrids resulting from crossing five inbred lines using the half-diallel method. These included Hybrid 1 = (1×4)(3×5) from the crossing of (ZM49W3E x CDCNS) (ZM43WIZE x ZM19), Hybrid 2 = (1×2)(3×5) from the crossing of (ZM49W3E × CDCN5) (ZM43WIZE x ZM60), Hybrid 3 = (1×5)(2×4) from the crossing of (ZM60 × ZM19) (ZM43WIZE ×CDN5), Hybrid 4 = (1×2)(4×5) from the crossing of (ZM19 × CDCN5) (ZM43WIZE ×ZM60), and Hybrid 5 = (1×4)(2×3) from the crossing of (ZM60 × ZM49W3E) (ZM43WIZE × ZM19), and their comparison with the synthetic variety IPA5018, and testing them under three planting dates: July 1^st, July 15^th, and August 1^st. The experiment used a randomized complete block design with four replications arranged in a split-plot design. The main plots included the three planting dates, while the subplots included the five double-cross maize hybrids and the control variety. Secondary  yield components were studied. The results of the experiment showed highly significant effects of the third date for all traits, as the date was superior in ear length (21.40), ear diameter (47.42), number of rows in the ear (15.73), number of grains in a row (41.88), number of grains in the ear (659.3), and ear weight (285.4). ). The hybrid(1×4) (3×5) was superior in terms of ear length, ear diameter, number of grains per row,  , and ear weight, reaching 20.45, 36.24, 36.49, 540.4, and 232.1Sequentially. The marital response of the hybrids varied according to planting dates and showed a significant interaction for all the traits under study, except for the ear length and the number of rows per ear.