Document Type : Original Article
Authors
1
. Res. Officer, Makien Hybrids, Egypt
2
Agron. Dept., Fac. Agric., Zagazig Univ., Egypt
3
Gen. manger and Head of R&D, Mid. Egypt Comp., Egypt
Abstract
Maize (Zea mays L.) is an important cereal crop due to its high forage and grain yield potential. The objective of this study was to assess mean performance and heterotic effects of 36 F1 hybrids with 4 checks under three planting densities, 24,000, 32,000, and 40,000 plants fed-1 at optimal sowing date (April 10th) and late one (May 28th) in the middle Egypt. Significant differences were recorded for all studied traits among maize hybrids in the six environments. The 2nd sowing date(SD) had negatively affected on all maize hybrids for all traits.The high plant density (HPD) and medium (MPD) one caused an increase in days to 50% tasseling (later in maturity), plant height (taller plants), and grain yield per feddan (increased by 17.77% and 1.01% in the 1st SD, and 14.8% and 8.65% in the 2nd SD under HPD and MPD, respectively). While, ear length, ear diameter, number of rows per ear, number of kernels per plant, 100- kernel weight, and grain yield per plant were reducedunder MPD and HPD. Grain yield varied from 16.6 to 44.89 ardabfed-1 in the 1st SD and varied from 11.55 to 35.40 ardab fed-1.in the 2nd SD. The hybrid L8×L9 had the highest average grain yield overall environments (35.13 ardab fed-1) followed by L1×L3, L1×L8, L3×L8, L3×L4, andL3×L5(32.65, 32.65, 32.5, 32.49 and 32.34ardab fed-1, respectively). Negative and significant desirable standard heterosis over check variety Pioneer 32D99 were recorded in crosses (L1×L4), (L1×L8), (L6×L7) and (L4×L8) for days to 50% tasseling and crosses (L3×L8), (L3×L9), (L5×L8) (L6×L7), (L6×L8), (L6× L9), (L7×L9) and (L8×L9) for plant height under most environments. Positive and significant heterosis estimates were recorded in crosses (L4 × L7) and (L4 × L9) for ear length in 2nd SD; cross (L1×L6) for ear diameter; crosses (L3×L8) and (L4 × L8) for number of rows per ear under most environments; crosses (L2×L6), (L2 × L9), (L4 × L7), (L6 × L9) and (L8 × L9) for number of kernels per row under all environments; cross (L8 × L9) for 100- kernel under all environments in the 1stSD and NPD in the 2nd SD as well as grain yield under HPD, it showed positive values.The percent heterosis for grain yield varied from -65.02 to 7.28%. Grain yield had positive and significant associations with plant height (0.672**), ear length (0.341*), ear diameter (0.375*), number of rows per ear (0.596**), and number of kernels per row (0.486**).The aforementionedpromising hybrids are recommended for further inclusion in the breeding program.
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