Exploring the effect of nitrogen levels on yield and yield attributes of diverse open-pollinated varieties (OPVs) of maize (Zea mays)

A field trial was carried out during the Kharif season of 2022 at the Agronomy Research Farm, University of Swabi. The trial was designed as a 3×3 factorial experiment, involving three varieties (CIMMYT FATA, DSW, and Kaptan) which were allocated to the main plots. Three levels of nitrogen (200, 150, and 100 kg ha−1) were applied to the subplots. A plot size of 22.5 m2, having 6 rows 75 cm apart with plant-to-plant distance of 25 cm was maintained. The concerned maize varieties were sown at the first week of July 2022. The required amount of N was applied at the time of second irrigation using urea fertilizer. Similarly, the recommended dose of phosphorus (TSP) and potassium (KCl) were applied at a rate of 60 kg ha-1 prior to the final ploughing. The field was cultivated twice with a cultivator and rotavator, and then leveled with a back leveler. Irrigation was managed according to weather conditions, and the water needs of the crop. Among the different maize varieties, Jalal variety significantly (p<0.05) delayed tasseling (54 days) and silking (61days), Plant height (193 cm), ear length (18.9 cm), 1000 grain weight (31 g), grains per ear (422), grain yield (5030 kg ha-1) and biological yield (12337 kg ha-1) were all improved when compared to DSW and CIMMYT FATA cultivars. However, the harvest index (43.7%) was highest for the DSW variety. The application of 200 kg ha-1 delayed silking (60 days) and tasseling (53 days), as well as enhanced plant height (192 cm), ear length (18.8 cm), grains per ear (411), thousand seed weight (305 g), biological yield (12036 kg ha-1), and grain yield (4995 kg ha-1) as compared to 100 and 150 kg N ha-1. Based on the study's findings, it is recommended that nitrogen be supplied at a rate of 200 kg ha-1and the Jalal variety be used to boost maize yield as well as yield components in the study area. © 2023 The Author(s)