Estimates of combining ability effects to new yellow maize (Zea mays L.)‎ inbred lines and its topcrosses

الملخص EN

Twelve yellow maize inbred lines isolated from five different sources at maize breeding nursery of Nubaria Agriculture Research Station were used for the present study.

These lines were topcrossed to two testers; Cim.325 and Gm.1002.

The 24 resultant topcrosses and the commercial check hybrid SC.162 were evaluated in replicated yield trials conducted at two locations; i.e., Nubaria and Sids.

Data were recorded for ears weight per plot(kg), number of days to mid-silking (d) and plant and ear heights (cm).

Ears were weighed in kg/plot, shelled, adjusted to 15.5% grain moisture and converted to grain yield in Mg ha-1.

Significant differences were detected among locations, lines and testers for the studied traits at each location and their combined data except grain yield of testers at Nubaria and combined data, and also number of days to mid-silking of lines at combined data.

The most superior crosses for grain yield were Nb.603b x Cim.325, Nb.556 x Cim.325, Nb.659a x Gm.1002, Nb556 x Gm.1002, Nb601 x Cim.325 and Nb.603b x Gm.1002, which yielded 10.55, 10.06, 10.06, 9.93, 9.70 and 9.68 Mg ha-1, across the tested locations, respectively.

Inbred lines Nb.603b and Nb.556 had significant GCA effects for grain yield, in addition, these lines had favorable alleles for early maturity, short plants and low ear placement.

These lines are the most superior inbred line and may be recommended for further test.

For the testers, Cim.325 lines had favorable alleles for grain yield, earliness, short plants and low ear placement, therefore, Cim.325 was recommended as a good tester for determining the superior crosses.

Regarding SCA effects, the topcrosses of Nb.516c x Cim.325, Nb.575 x Gm.1002 and Nb.545 x Gm.1002 possessed high negative SCA values.

Results showed that both GCA and SCA effects should be taken into consideration when planning maize breeding programs for developing new inbred lines and crosses.