Evaluation of the performance of the double crosses of maize under planting dates suitable for the fall season in the middle region (field traits)

Abstract

With the aim of evaluating the performance of double crosses at planting dates that are suitable the fall season in the middle region of Iraq, a field experiment was conducted in the fields of the College of Agricultural Engineering Sciences - University of Baghdad - Al-Jadriya for the fall season 2022 using superior double crosses of maize were chosen from fifteen double crosses    . It was obtained from the  crossing of ten single crosses resulting from the  crossing of five inbred lines (1=ZM43WIZE , 2=ZM60 , 3= ZM49W3E , 4=ZM19 ,5=CDCN5) by the half- dialle crossing method . Hybrids (3×5)(1×4),(3×5)(1×2),(2×4)(1×5),  (4×5)(1×2),  and (2×3)(1×4)  , compared it with the synthetic cultivar IPPA 5012 and tested it under three planting dates:1^st July, 15^th July  and  1^st August. The Randomized Complete Block Design (RCBD) was used with four replicates in split plots arrangement. The main plots included the three planting dates and the secondary plots were double crosses with the comparison cultivar IPPA5012. The following traits were studied: number of days from planting to 50% tassling and   silking, plant height, ear height, number and area of ​​leaves. The results showed that the hybrid (3×5) (1×2) reached the tassling-and silking-earlier, taking 50.83 and 54.33 days, respectively. The same hybrid also outperformed by giving it the highest  plant height , ear height , number of leaves and leaves area, as they reached (195.4 cm, 114.3 cm, 14.30 leaves, and 6588 cm ²) respectively. The plants of the   date of 1^st August were early with tassling and  silking, as they need 50.75 and 53.50 days, and the date  1^st July  did not differ significantly from 15  July in these two trait. The date 1^st August  was also superior in plant height, ear height, and leaf area, reaching 193.2 cm, 106.1, and 6375 cm². And there were no significant differences between the three dates in number of leaves. The interaction was significant between the two studied  factors  for the traits of tassling and silking  , plant height and number of leaves, but it was not significant for   ear height and leaf area