ESTIMATES OF COMBINING ABILITY AND HETEROSIS EFFECTS FOR GROWTH, EARLINESS AND YIELD IN MAIZE (Zea mays-L)

Document Type : Original Article

Authors

1 Dept. of Agronomy, Fac. of Agric., AI-Azhar University, Cairo, Egypt.

2 HYTECH Co. station, Kaha, Kalyubia, Egypt.

Abstract

A half diallel cross analysis among eight inbred lines were evaluated for
tassling date, silking date, plant height, ear height, ear length, ear diameter, no. of
rows/ear, no. of kernels/row, weight of 100 kernel and grain yield/plant. The eight
parents and their 28 F1, (36 entries) were evaluated in a randomized complete
blocks design with three replications in 2001 season. Results indicated to significant
variances due to general and specific combining abilities for all the studied traitsil
except for plant height, which were insignificant for general combining ability. P
was a good general combiner for grain yield{plant and p < sup>8 was a good general
combiner for earliness Hybrid combination p4Xp , p4Xp < /sub>6, p1Xp < /sub>8 and p5Xp < /sub>7 exhibited
desirable S.CA effects. High rations which largely exceed the unity were obtained
in ear length, no. of rows/ear and weight of 100 kernel. While the rations were less
than unity for all of the other traits indicating that the largest part of the genetiC
variability associated with those traits was a result of non-additive gene action.
Results obtained the obtained results indicated that heterosis (parent. vs. crosses)
was generally pronounced for all studied traits except 100 kernel weight. Compared
to mid and better parent, the highest heterotic effect was registered by hybrid p4Xp < /sub>8
for grain yield/plant and most of yield components, while p3Xp < /sub>6 was the best
heterotic effect for earliness. It could be concluded that these crosses would be
efficient and prospective in maize breeding programs for improving the grain
yield/plant.