Journal of Applied Biosciences (J. Appl. Biosci.) [ISSN 1997 - 5902]
Volume 48: 3270 - 3278. Published December 29, 2011.
Structural morphology of Cassava (Manihot esculenta Crantz) genotypes influenced yield and responses to weed management in the Guinea savanna zone of Nigeria.
1Agahiu, A. E; *Baiyeri, K. P. and R. O. Ogbuji
Dept. of Crop Science, University of Nigeria, Nsukka, Enugu State, Nigeria.
1Dept of Crop Production, Kogi State University, Anyigba, Kogi State, Nigeria
*Corresponding author: paul.baiyeri@unn.edu.ng; paulkayodebaiyeri@yahoo.com
ABSTRACT
Objective: The effects of nine weed management options on the yield and components of yield of two cassava (Manihot esculenta Crantz) morphological types were evaluated for two cropping seasons in a guinea savanna site of Nigeria.
Methodology and result: Field experiments were carried out during the cropping seasons of 2008 and 2009 at the Teaching and Research Farm of the Department of Crop Production, Kogi State University, Anyigba (Lat 70 29' N and Long 70 11' E), Nigeria. The experiment was laid out in a split-plot in randomized complete block design replicated three times. The main plots consisted of the two cassava morphological types - ‘NR 8082’ (short with profuse branching) and ‘TMS 30555’ (tall and non-branching). Nine weed management options including the application of 3.0, 3.5 and 4.0 kg a.i/ha of Primextra (atrazine x metolachlor), 2.0, 3.0 and 4.0kg a.i/ha of Taxastomp (atrazine x pendimethalin) [designated P3.0, P3.5, P4.0 and T2.0, T3.0, T4.0, respectively], three-time manual weeding, weedy and weed-free checks were the subplot treatments. The predominant weeds were Cynodon dactylon, Panicum maximum, Andropogon gayanus, Chloris pilosa and Bracharia deflexa constituting about 80% of the weed mass in the field. Except for the weedy check, weed fresh biomass (1.03 - 1.19 t/ha) and the dry matter (0.06 - 0.09 t/ha) were highestin plots to which 2.0 kg a.i/ha of taxastomp was applied. The two cassava morphotypes exhibited significant differences (P < 0.05) in plant height across the two-year trials and weed management systems, with the tallest stem height (153.5cm) obtained from the non-branching variety in the P3.0 treated plot. The highest cassava biomass (12.1 - 14.1 kg) was obtained from the P3.0 treated plots across morphological-types and year; and closely followed by plants in the T3.0 plots. However, harvest index was highest in the T2.0 treated plot irrespective of cassava morphological-types. Of all the treatments, P3.0 and T3.0 (i.e. 3.0 a.i. kg/ha) gave the highest root tuber yield (119.7 and 117.0 t/ha, respectively) from the non-branching type in both years as against 100.67 and 103.67 t/ha for the branching morphological type.
Conclusion and application of findings: Variable response pattern of the two cultivars to the weed management options evaluated suggested that morphological differences of the cultivars may have influenced effectiveness of herbicides applied. However, the application of Primextra and Taxastomp at 3.0 a.i. kg/ha seemed most appropriate for weed control in cassava fields in the guinea savanna zone of Nigeria.
Key Words: Cassava morphology, Yield and yield components, Weed management
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