POTENTIAL OF MAIZE INBRED LINES TO IMPROVE HYBRIDS

Abstract

The choice of donor inbred lines as sources of favorables alleles for the improvement of an elite hybrid is an essential part of a hybrid maize (Zea mays L.) program. The objectives of this study were to: 1) Identify CIMMYT lines by their potential to improve grain yield, root lodging and ear rotten of three hybrids AN1 x AN2, SSE232-33- 30 x SSE255-18-19 and SSE255-18-19 x M.L.S4-1; and 2) Compare the relative number of favorable alleles in loci class G (µĜ) with the original unbiased estimator (µG), the general combining ability (GCA), the predicted three-way cross (PTC), the three-way cross prediction (TWC), the minimum upper bound (UBND), the net improvement (NI), the probability of a net gain (PNGg), the unbiased estimator of the potential of an inbred line (µa(B+G)), and the inbred performance per se. Crosses among 23 donor inbreds with the parents of the three elite hybrids and the per se inbreds were evaluated at three locations during the 1997 summer season. Parameters µĜ, µG, GCA, PTC, TWC, UBND, NI, PNGg, µa(B+G) and inbred per se showed significant differences among donors for grain yield. The inbred line CML312 can be used for improving grain yield in the three target hybrids. Simultaneous improvement for grain yield, root lodging and ear rotten, in the target hybrids can be achieved with several inbred donors. Correlations among ten estimators for grain yield were high, positive and significant; the highest correlations (r=1.0**) were detected between µĜ with GCA and PTC; GCA with PTC; NI with TWC, and µG with µa(B+G).