Journal of Applied Biosciences (J. Appl. Biosci.) [ISSN 1997 - 5902]
Volume 20: 1194 - 1202. Published August 7, 2009.
Response of two maize varieties to density and nitrogen fertilizer in the highland zone of Rwanda
Sallah P.Y.K.*, Mukakalisa S**., Nyombayire** A. and Mutanyagwa P**.
* Department of Crop Science, Faculty of Agriculture, National University of Rwanda (NUR), P.O. Box 117, Butare, Rwanda; **Institut des Sciences Agronomiques du Rwanda (ISAR), BP. 73, Ruhengeri, Rwanda
*Corresponding author email: pyksallah@yahoo.com
ABSTRACT
Objectives: To determine grain yield response to plant density and N fertilizer application in maize (Zea mays L.) and formulate appropriate recommendations for growers in the highland (1800 to 2400 m asl) zone of Rwanda.
Methodology and results: Two open-pollinated maize varieties, Mamesa (early maturing) and Tamira (late maturing) were evaluated at three densities (30 000, 50 000 and 70 000 plants ha-1, coded as D1, D2 and D3, respectively and three N levels (0, 80, 160 kg N ha-1) using a split-split plot design at Ruhengeri and Tamira in the highland zone during the 2007/08 growing season. Varieties were randomized in the main-plots, plant densities in the sub-plots, and N levels in the sub-sub plots with three replications per location. The density x nitrogen interaction was significant and optimum N rates for maximum grain yields from response curves were determined to be 107, 112 and 117 kg N ha-1 for D1, D2 and D3, respectively. Predicted yields at the optimum N levels were 5.90 t ha-1 for D1, 7.70 t ha-1 for D2 and 7.90 t ha-1 for D3, and were all not significantly different from yields at the usually recommended rate of 80 kg N ha-1.
Conclusion and application of findings: A population of 50 000 plants ha-1 and application of 80 kg N ha-1 gave the highest yields and is recommended for profitable maize production in the highland zone of Rwanda.
Key words: Plant density, nitrogen response, highland, maize cultivars
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