Study of the Genetic Diversity of Some Genotypes of Maize Under Two Levels of Nitrogen Fertilization

Abstract

The present study aimed to determine the genetic divergence of seven maize genotypes (Al-Maha, Sumer, Al-Fajr, Baghdad, 5018, 4 × 1 single hybrid, and 4 × 2 single hybrid) under two varied levels of nitrogen fertilization (92 and 276 kg N ha-1). The experiment occurred in 2022 in a randomized complete block design (RCBD) with a split-plot arrangement and three replications at the College of Agricultural Engineering Sciences, University of Baghdad, Iraq. The nitrogen fertilization levels served as main plots, with the maize genotypes allocated as the subplots. The results revealed that genetic variance was higher than the environmental variance for most traits, and the coefficient of phenotypic variation was close to the genetic variation coefficient under the two levels of nitrogen fertilization. Heritability (broad sense) at the 92 kg N ha-1 (N1 level) was the highest for traits. i.e., ear height, grains per row, grains per ear, individual plant yield, yield per unit area, days to 50% male flowering, leaf area, ear length, rows per ear, and 100-grain weight, with values of 92.556%, 90.760%, 90.123%, 95.007%, 95.007%, 88.976%, 89.974%, 88.748%, 85.521%, and 89.690%, respectively. For the N level of 276 kg ha-1 (N2 level), the heritability in a broad sense was high for the traits, viz., days to 50% male flowering (91.546%), plant height (96.150%), ear height (91.038%), ear length (92.454%), individual plant yield (98.108%), yield in the unit area (98.108%), and plant dry weight (85.488%). The cluster analysis divided the maize genotypes into four and five cluster groups under the nitrogen fertilization level of 92 and 276 kg N ha-1, respectively. These different groups of maize genotypes could be due to the genetic divergence among the genotypes resulting from their varied genetic makeup and origin.

Maize Seed Inoculation With Bioagent and Its Effects on the Growth and Yield Traits

“…The significant increase in yield might be due to the breeding of high-yielding cultivars, mineral fertilizers, and crop management. Maize has very high nutrients' requirement, and using chemical fertilizers has caused severe environmental issues, such as, air pollution, water eutrophication, and soil acidification (Mateo-Sagasta et al, 2017;Zeffa et al, 2019;Ali and Alshugeairy, 2023). The negative environmental impact of mineral fertilizers demands an alternative source of nutrients, i.e., beneficial soil microorganisms, also known as plant growth-promoting microorganisms (PGPM) (Majeed et al, 2020).…”