Variability of grain-filling traits in early maturing CIMMYT tropical maize inbred lines

Abstract

Grain-filling rate (GFR), effective grain-filling duration (EGFD), and total grain-filling duration (TGFD) are important physiological traits of maize (Zea mays L.) grain yield (GY) formation. To devise effective breeding strategies, the genetic nature of these traits is a prerequisite for improvement in early maturing maize. A study was conducted at CIMMYT-Zimbabwe using an α-lattice design with two replications in two environments to investigate the genetic variability of grain-filling traits in 18 early maturing tropical maize inbred lines derived from CIMMYT germplasm. Highly significant differences were observed for GY, thousand-grain weight (TGW), GFR, EGFD, TGFD, kernels per row (KR), and rows per cob (RC). The broad-sense coefficient of genetic determination (the fixed parent equivalent of broad-sense heritability) was above 70% for all of the traits. The highest GY was obtained from the inbred line T032-30 (79.2 g plant–1) and the lowest from inbred line CML506 (37.6 g plant–1), respectively. Therefore, selecting for higher GFR and longer TGFD, especially the EGFD, can increase GY of early maize without extending days to physiological maturity (DPM).