CHAPTER ONE

INTRODUCTION

Maize (Zea mays L.) is one of the most important cereal crop grown principally around the world. Maize grain is used for both human consumption and animal feed. It has great utility in agro industry as a source of raw materials for many products. The crop has much higher grain protein content than our staple food like rice (Oyekan et al. 1989). Based on area and production, maize is the third most important cereal crop after wheat and rice in the world.

                       The yield of maize in Nigeria is very low as compared to other maize producing countries (Nasir 2002). One of the mPost important responsible factors is the non-application of optimal plant population and the fact that maize hybrids differ in their response to plant density (Xue et al. 2002). As maize do not have tillering capacity to adjust to variation in plant stand, optimal plant population for grain production is very important. Agronomic practices such as plant population is known to effect crop environment, which influence yield and yield components. Optimum population levels should be maintained to exploit maximum natural resources, such as nutrient, sunlight, soil moisture and to ensure satisfactory yield (Allard 2000). When plant density is high, it encourages inter plant competition for resources; then crop net photosynthesis will be affected due to less light penetration in the crop canopy as well as increase in competition for available nutrient which will affect grain yield(Sharrath and McWilliams, 2005). On the other hand if plant population is lower than optimum plant population, then per hectare production will be low and weeds will be more (Khan. 1972).

                    Maize is a crop that has wide adaptation to varied environments. Extra-early and early maturing varieties of maize are now available to expand production to marginal areas of production, particularly areas with low rainfall and sparse distribution. The early and extra early varieties can also be grown effectively in high rainfall areas as early and late season crop, or can go for a third cycle in one year.

                        Extra-early and early maturing maize varieties are usually smaller than the late and medium maturing varieties and also yield less than the former. Adjusting the plant population to higher rate than the recommended plant population for late and medium varieties and will improve grain yield of early and extra-early varieties.                         The objective of this study is therefore to determine the optimum spatial arrangement and plant population that will give the best agronomic response and performance of early and extra-early maturing varieties in the humid tropics environment.