EFFECT OF CHEMICAL WEED CONTROL AND INTRA-ROW SPACING ON THE GROWTH AND YIELD OF POPCORN (ZEA MAYS L. VAR. EVERTA) IN THE NORTHERN GUINEA SAVANNA OF NIGERIA
A.K. GANA, J.A. ADIGUN, K.O. ADEJONWO, B.W. NDAHI, L.D. BUSARI
Abstract
Field trials were conducted to study the effect of
herbicide treatments and intra-row spacing on the growth and yield of popcorn
(Zea mays L. var. everta) at the Institute for Agricultural Research Farm, Samaru
(11 °11', 07°38'E) in the northern Guinea Savanna of Nigeria in 1995
and 1996 wet seasons.
In both years of experimentation, the use of herbicides (except metolachlor
plus me-tobromuron at 1.0 + 1.0 kg a.i./ha) and hoe-weeding consistently resulted
in significantly lower weed cover score, weed dry matter production and higher
grain yields compared with the weedy check. However, the most promising herbicide
treatments (interms of weed control and popcorn grain yield) in this study were
pre-emergence application of metolachlor at 2.0 kg a.i./ha and its combination
with atrazine at 1.0 + 1.0 and 1,25 + 7.25 kg a.i./ha, each followed by supplementary
hoe-weeding at 7 weeks after sowing (WAS). These treatments resulted in higher
popcorn grain yield than other herbicide treatments and were comparable to the
hoe-weeded control. Unrestricted weed growth throughout the crop life cycle
resulted in 83.3 and 72.9 % reduction in popcorn grain yield compared to the
maximum obtained in 1995 and 1996 wet seasons respectively. In both years, crop
planted at intra-row spacing of 15 cm on 75 cm ridges resulted in significantly
lower weed cover score than those of 30 and 45 cm spacing at 6 and 9 WAS. Similarly,
weed dry matter production was significantly reduced at 15 cm intra-row than
those of 30 and 45 cm spacing. Crop vigour and plant height at 6 and 9 WAS,
and popcorn grain yield increased significantly at 15 cm than 30 cm and 45 cm
spacing. The interaction between weed control treatments and intra-row spacing
on weed cover score at 9 WAS, weed dry matter production and grain yield in
both years were significant. In this, interaction mixture of metolachlor plus
atrazine at 1.0 + 1.0kg a.i./ha applied pre-emergence under the intra-row spacing
of 30 cm combined effective weed control with high popcorn grain yield comparable
to the hoe-weeded control.
Key words:
Zea mays L., popcorn, chemical weed control, intra-row
spacing, Nigeria.