Abstract:
Maize is an important cereal crop grown in Sri Lanka. Hybrid varieties are popular
among farmers and the extent cultivated with hybrids has increased over the last few
years. Department of Agriculture released the first local hybrid maize variety
(Sampath) in 2004. Agronomic practices recommended for open pollinated varieties
are not appropriate for highly input responsive hybrids. Therefore, a study was
undertaken at Field Crops Research and Development Institute, Mahailluppallama
for two consecutive seasons to determine a suitable plant density for hybrid maize.
Four densities namely, 55555 (present recommendation), 74074, 88888 and 111111
plants/ha were tested with two varieties (Pacific 984 and Sampath) at 200kg ha-1 N,
100 kg ha-1 P2O5 and 50 kg ha-1 K2O. Grain yield increases observed in maha
2004/05 for 74074, 88888 and 111111 plants/ha were 88 kgha-1 (2%), 1114 kgha-1
(21%) and 1708 kgha-1 (30%) respectively and 247 kgha-1 (4%), 1434 kgha-1 (24%)
and 1958 kgha-1 (33%) in yala 2005. Two varieties gave the same yields and
variations in leaf area, plant height, ear length and 100 seed weight were found not
significantly different. Seed number per ear was reduced by 10-16% at higher
densities. Economic analysis revealed that profitability increased by Rs.7000.00-
11,000.00/ha both at 88888 and 111111 plants/ha densities.
