IMPROVING GRAIN YIELD AND YIELD COMPONENTS VIA BACKCROSS PROCEDURE

Transferring a quantitative trait from a donor maize (Zen may L.) line into a local elite line is an important way to improve local maize line. A backcross procedure is widely used method for this purpose. However, little knowledge exists on how effective a backcross procedure is for improving one and/or multiple quantitative traits of maize. The objectives of this study were to 1) determine the backcross generations at which a quantitative trait was recovered to a similar homozygous level of recurrent parent; 2) investigate if multiple quantitative traits can be transferred from a donor line into a local elite line in a consecutive backcross procedure. 3) evaluate if the parental lines' mean, GCA, and SCA effects impact on the changes in the studied traits at different backcross generations. The results had shown that four consecutive backcross generations are necessary to make a new line recover to similar homozygous level of recurrent parent in the studied quantitative traits. Multiple quantitative traits from exotic donor line have been successfully transferred into the new line by the consecutive backcross procedure incorporated with key agronomic trait selection. A maize line with high means from recurrent parent lines (RPL) and high positive GCA effects from both parent lines is preferred to SCA effect in a cross for improving quantitative traits of a recipient line because fixation of additive genes can occur in consecutive backcross generations.