Response of Soyabean (Glycine max (l.) Merril) Varieties to Weed Control Treatments and Row Arrangement in the Nigerian Savannah

ABSTRACT

Field were conducted during the 2012 season at Samaru located 11⁰ 11‟N 07⁰ 38‟E, 686 metres above sea level in the Northern Savannah and during the 2012/2013 dry season at Kadawa located 11⁰ 39‟N 08⁰ 02‟E,

500 metres above sea level in the Sudan Savannah ecological zones of Nigeria, to study the effect of weed control treatments and row arrangement on soyabean varieties. The experiment consisted of five weed treatments which included application of Butachlor and Pendimethalin each at 2.5 kg a.i ha^-1,

one hoe weeding at 3 weeks after sowing, two hoe weeding at 3 and 6 weeks after sowing and a weedy check with two soyabean varieties; (TGx 1835-10E and TGx 1987-62F) and two row arrangement; (Single and double row).

The treatments were laid out in a split plot design with factorial combination of weed control treatments and row arrangement on the main plot while varieties were assigned to the sub-plots.

Results indicated that weed dry weight and weed cover score were significantly lower in the weed control treatments than the weedy check .

Plots treated with Butachlor at 2.5 kg a.i ha^-1 and those weeded twice at 3 and 6 WAS resulted to significantly higher values for crop vigour, plant height and canopy spread. At 6 and 9 WAS plots weeded once or twice had wider canopy spread at both locations.

There was significant increase in the crude protein (0.5%) and oil content (0.8%) with the application of Pendimethalin at 2.5 kg a.i ha^-1 compared to the other weed control measures and the weedy check.

Yield parameters including number of pods per plant, seeds per pod, dry biomass, 100 seed weight and grain yield were also significantly increased in plots weeded twice.

Double row arrangement of soyabean recorded the least weed dry weight, weed cover score and produced significantly more vigorous crops with wider canopy spread, heavier dry biomass and also improved the oil content of the crops compared to the single rows.

Variety TGx 1987-62F recorded lower weed dry weight and produced significantly taller and more vigorous crops with wider canopy though delayed flowering and produced more number of pods with heavier dry biomass and higher grain yield at Samaru,

however at Kadawa variety TGx 1835-10E produced significantly more seeds per pod, 100 seed weight and grain yield. There was positive and significant relationship between soyabean grain yield and parameters like plant height, crop vigour, canopy spread, dry biomass and number of pods per plant.

There was however negative and highly significant association between grain yield with weed dry weight and weed cover score.

In conclusion the results obtained from this study indicated that plots weeded twice at 3 and 6 WAS and double row arrangement of the two soyabean varieties resulted in effective long season weed control at both locations.

Variety TGx 1987-62F performed better during the rainy season at Samaru while TGx 1835-10E performed better at Kadawa during the dry season.

INTRODUCTION

1.1. Background to the Study

A city is said to be monocentric in nature when it is characterized by a unicentered Central Business District (CBD). The monocentric city model was formulated by Alonso in 1964 as an adaptation of Von Thunen‟s 1826 theory of agricultural land and land use to the urban case.

This idea was immediately expanded to include production, transport and housing and has been generalized in many ways (Mills, 1967, 1972; Muth, 1969; Fujita, 1989).

Moreover, the basic design model for monocentric city is envisaged as circular residential area or district surrounding CBD in which all jobs are located.

The model further distinguishes between an open city (with perfectly elastic population) and a closed city (with fixed population that is fairly inelastic) (Anas and Kim, 1996).

This city model has been the dominant view of urban land use structure since the early 90s by the urban economists, as it allows for easy generation of rent gradient in transportation friction for commuting or commerce between a city center and periphery (Wheaton, 2004).

However, when population and density of the city change, the gradient become steeper as travel distance to the CBD increases and speeds for accessing such facility deteriorate.

The monocentric urban spatial form has been the model most widely used to analyze the spatial organization of cities in the United State of America e.g. Chicago, New York and Los Angeles.

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