EVALUATE THE PERFORMANCE OF DOUBLE, SINGLE HYBRIDS AND INBREDS OF MAIZE UNDER DIFFERENT PLANT DENSITIES AND ESTIMATE THE PERCENTAGE OF HETEROSISAND HYBRID VIGOR((yield and its components))

Abstract

A field experiment was conducted during the fall Season 2017 at the fields of Field Crop Department, College of Agriculture, University of Baghdad in order to evaluate the performance of double and Single hybrids, and their inbreds of maize in two plant densities. The Study included the comparison among five inbreds (ZM43WIZE, ZM60, ZM49W3E, ZM19 and CDCN5), ten single hybrids, and fifteen double hybrids , resulting from their crossing with two plant densities (60000, 80000 plant.ha-1). The experiments were conducted according to the randomized complete block design (RCBD) with three replications, using the spilt plots arrangement, where the two densities (60000, 80000 plant.ha-1) were represented in the main plots and the 30 genotypes in the sub-plots. The results showed the superiority of the single and double hybrids over their inbreds in all the studied traits. The double hybrids (2x3) (4x5) gave the highest length of ear amounted of (19.98 cm), number of rows per ear (15.38), number of grains per ear (38.98), number of grains per plant (667.1), number of ear per plant (1.17), and the plant yield increased the accordingly reaching185.8 g per plant. The single hybrids (5 × 3) has excelled by giving it the highest plant yield amounted of 184.2 g. This was due to the superiority of the length of ear, which reached (18.42 cm), number of rows per ear (15.42), number of grains per row (35.24), number of grains per plant (653.6) and number of ears per plant (1.20).These two hybrids had highly positive heterosis and hybrid vigor in the desired direction where amounted (6.36%, 3.53%), (9.47%, 87.0%), (5.27%, 3.36%), (7.47%, 0.15%) and (14.2%, 1.44%) for the length of ear, number of rows per ear, number of grains per row, and number of grains per plant, respectively. The heterosis and hybrid vigor for the hybrid (2x3)(4x5) recorded the highest value for the trait of grain yield amounted of (30.2%, 29.2%), respectively, While the hybrid (3x5) gave heterosis and hybrid vigor (5.66%, 17.4%), (26.9%, 35.5%), (20% ,20%), (8.35%, 15.4%), (1.44%, 4.18%), (13.4%, 23.3%), (44.9%, 54%) for the same traits, respectively, and it gave the highest value of total grain yield amounted of (93.8%, 90.2%). The fifth inbred excelled on the others inbred by giving it the highest yield (96.8 g). Increasing in the plant densities from 60 to 80 thousand plants ha-1 led to a decrease in the number of ears, length of ear, number of grains per row, number of grains per plant, and the individual plant yield. The interaction between genotypes and plant densities was significant for all traits except number of ears per plant.