Effect of time of introducing maize on yield of white guinea yam (Dioscoreae rotundata P.) minisetts in Makurdi, Nigeria

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1 AGRICULTURE AND BIOLOGY JOURNAL OF NORTH AMERICA ISSN Print: , ISSN Online: , ScienceHuβ, Effect of time of introducing maize on yield of white guinea yam (Dioscoreae rotundata P.) minisetts in Makurdi, Nigeria Ijoyah, M.O. Department of Crop Production, University of Agriculture, P.O. Box 2373, Makurdi, Benue State, Nigeria ABSTRACT A field experiment was conducted from May to October, during the years 2003 and 2004 planting seasons at the Research Farm of the University of Agriculture, Makurdi, Nigeria, to evaluate the effect of time of introducing maize on yield of White Guinea yam (Dioscoreae rotundata P.) minisetts. The experiment consisted of three maize introduction dates to yam-minisett plots. These were: maize planted same time as yam-minisetts, maize introduced 3 weeks after planting (WAP) yam-minisetts and maize introduced at 6 WAP yam-minisetts. The three maize introduction dates constituted the treatments, which were laid out in a randomized complete block design with three replications. The results obtained showed that the greatest number of tubers, tuber weight per plant and tuber yield were obtained from yam-minisett planted at same time as maize. In the year 2003, tuber yield obtained from yam-minisett planted at same time as maize was significantly (P 0.05) greater by 17.2 % and 31.0 % respectively, compared to that obtained from yam-minisett that had maize introduced at 3 and 6 weeks later. Similarly, tuber yield produced in 2004 was significantly (P 0.05) greater by 9.5 % and 19.7 % respectively, compared to that obtained from yam-minisett that had maize introduced at 3 and 6 weeks later. The implication of this study showed that the greatest tuber yield is obtained when yam-minisett is planted at same time as maize and could therefore be recommended for Makurdi location, Nigeria. Keywords: Maize, Planting dates, Yam-minisett, Tuber yield. INTRODUCTION Yam and maize are Nigeria s leading crops both in terms of land under cultivation and preferred major staple food crops contributing immensely to rural and regional economies (Agboola, 2000). The Southern Guinea savanna zone of Nigeria is a major yam and maize producing area. Yams and maize are the most important food crops in the zone (Osiru et al., 1987). Over 50 % of the yam (Dioscoreae spp.) and 75 % of the maize grown in Nigeria are produced under intercropping systems (Okigbo and Greenland, 1996). Recent studies in the zone have shown a high potential and suitability of the use of (D. rotundata) as minisetts in the rapid production of seed and ware yam (Kalu and Ortese, 1993). Unamma (1999), in his studies on intercropping, reported that maize when introduced at three weeks after planting yamminisetts depressed the yield of yam-minisetts by about 28 %. Madu and Nwosu (2001), in their work on the productivity of yam-minisetts as influenced by maize introduction dates reported that delaying the time of maize introduction did not improve yamminisett tuber yield. Makurdi, which falls within the Guinea savanna zone of Nigeria, is represented by a different set of climatic factors such as rainfall, temperature and relative humidity, therefore the degree of expression of such effects could be different. With the climatic factors typical in the district, it became necessary to evaluate the possible effects that different time of maize introduction would have on the yield of yam-minisetts with the objective of identifying the best time of introducing maize that will optimize yam-minisett yield. MATERIALS AND METHODS The experiment was conducted from May to October, during the years 2003 and 2004 planting seasons, at the Research Farm of the University of Agriculture, Makurdi, Nigeria, to evaluate the effect of time of introducing maize on yield of White Guinea yam (Dioscoreae rotundata P.) minisetts. The study location falls within the Southern Guinea savanna agro-ecological zone of Nigeria. The local variety of White yam used was Dan Onicha, while that of maize was the Downy Mildew Early Streak Resistance-White

2 (DMESR-W). Both varieties of crops are popularly grown by farmers and shows good adaptation to the local environment (Kalu and Erhabor, 1992). Intact ware yam tubers of variety Dan Onicha, free from bruises and rot were selected from the previous year s harvest. Minisetts weighing about 25 g were cut from the ware yam tubers. Yam-minisetts and maize were treated with Apron plus powdery chemical to prevent seeds from fungal infection after planting. The cut surface of treated yam-minisetts were air dried to allow for curing three days before planting (Unamma, 1999). The experimental area (900 m 2 ) which consisted of sandy-loam soil was ploughed, harrowed, ridged and divided into three main treatment plots. Each plot had an area of 100 m 2. The plot consisted of ten ridges, in which 40 yam-minisetts per ridge were planted at a spacing of 100 cm x 25 cm, giving a total plant population of 400 yam-minisetts plants per plot (40,000 plants per hectare equivalent). Yam-minisetts were planted about 6 cm deep, in single row on top of the ridges. Maize was planted at the same time as yam-minisetts in the first treatment and later introduced at 3 and 6 weeks respectively, for the second and third treatment plots. Maize was also spaced 25 cm apart in single row, by the side of the ridges to give a plant population of 400 maize stands per plot (40,000 plants per hectare equivalent). The three maize introduction dates to yam-minisett plots constituted the treatments, which were laid out in a randomized complete block design (RCBD) with three replications. Two top dressings with mixed fertilizer NPK (12:12:17) at the rate of 120 kg/ha was applied following the recommendation by Ekpete (2000) at 3 weeks after planting maize and repeated six weeks later for each plot. Weeding was done manually using the hoe as the need arose. Harvesting of yam tubers was done in mid-october when large portion of the leaves were dry. Data taken included the establishment count of yamminisett. The presence of two expanded leaves on a vine was used as an indication of stand establishment (Kalu and Erhabor, 1992). Others are leaf area index of yam-minisetts at 120 days after planting (DAP), frequency of tuber twining, number of tubers per plot, tuber weight per plant and tuber yield (t/ha). The data were subjected to Analysis of Variance (ANOVA) while the Least Significant Difference (LSD) was used to separate treatment means (Steel and Torrie, 1980). RESULTS AND DISCUSSION The meteorological information of the trial site at Makurdi, Nigeria for the growth period from May to October, 2003 and 2004 is presented in Table 1. The average monthly temperature over the years ranged from C C. The average relative humidity ranged from 71.3 % %. The temperature and relative humidity range were considered optimal for the growth and development of yam and maize. This view supports Okoli (2000) who reported that optimal temperature range of C and humidity range of % is ideal for yam and maize. Generally, rainfall recorded was optimal during the growth period of the component crops (Table 1). The table shows that the month of September recorded the highest amount of rainfall and highest number of rainy days. In Table 2, total nitrogen (N) value in the soil over the years was low (0.14 % and 0.07 %). The table shows that the soil had a medium level of phosphorus (P) (9.8 ppm and 10.1 ppm) with a corresponding low level of potassium (K) (0.22 % and 0.14 %) for the years 2003 and 2004 respectively. Relatively moderate amounts of exchangeable bases calcium and magnesium (Ca and Mg) were present in all the soil units. Over the years, organic matter was low (2.5 % and 1.4 %) while the ph in water was near neutral (Table 2). In Table 3, the yield performance of yam-minisett as affected by maize introduction dates during the 2003 and 2004 planting seasons is given. The establishment count of yam-minisett was not significantly affected when maize was introduced at the three different dates. Over the years, leaf area index (LAI) of yam-minisetts at 120 days after planting (DAP) decreased with later introductions of maize (Table 3). Planting maize same time as yam-minisetts produced the largest leaf area index of 3.27 and 3.16 respectively, in the year 2003 and This could be due to the fact that at this period, minisetts might have had an appreciable leaf growth with a sparse shading effect of maize, which might have prompted the yam-minisetts to make efficient use of a longer day length, thus, promoting the largest leaf area. This view, supports Okonkwo (2001), who reported a decrease in leaf area for yam-minisetts 483

3 with a delayed maize introduction date up to six weeks. Although, the frequency of tuber twining was not significantly affected by the three different dates (Table 3), however, the greatest number of tubers, tuber weight per plant and tuber yield were obtained from yam-minisett planted at same time as maize. The largest leaf area obtained from yam-minisetts planted at same time as maize might have also accounted for the greatest tuber yield. In the year 2003, the number of tubers, tuber weight per plant and tuber yield obtained from yam-minisetts planted same time as maize were significantly (P 0.05) greater by 2.9 %, 3.2 % and 17.2 % respectively, compared to those produced from yam-minisett plots that had maize introduced 3 weeks later and by 5.7 %, 4.6 % and 31.0 % respectively, compared to those obtained from yam-minisett plots that had maize introduced 6 weeks later. Similarly, in the year 2004, the number of tubers, tuber weight per plant and tuber yield produced from yam-minisett planted at same time as maize were significantly (P 0.05) greater by 3.1 %, 2.7 % and 9.5 % respectively, compared to those obtained from yam-minisett plots that had maize introduced 3 weeks later and by 7.5 %, 4.3 % and 19.7 % respectively, compared to those obtained from yam-minisett that had maize introduced 6 weeks later. This view agreed with the findings of Uzozie (2001) in a similar work on cassava-maize intercrop, who reported that best cassava yield was obtained when maize was planted at same time or not more than three weeks later. Table 1. Meteorological information for Makurdi, Nigeria (May-October) 2003, Average monthly Average monthly Average relative Months rainfall (mm) temperature ( 0 C) humidity (%) 2003 Max. Min. May 135.4(8) June 241.0(11) July 204.8(11) August 243.0(16) September 287.3(18) October 98.7(9) May 98.0(11) June 161.5(11) July 87.4(9) August 156.2(12) September 247.2(15) October 243.3(7) Values in parenthesis indicate number of rainy days. Source: Air Force Base, Makurdi, Meteorological Station. Table 2. Physico-chemical properties of the soil of experimental site before planting in 2003 and Quantity in Soil Parameters Method of analysis Organic matter 2.5 % 1.4 % Walkley-Black method Nitrogen 0.14 % 0.07 % Kjeldahl method P 2 O ppm 10.1 ppm Flame photometric K 0.22 % 0.14 % Oxidation method Ca 4.07 meq/100 g 3.80 meq/100 g A.A.S. Mg 1.45 meq/100 g 1.20 meq/100 g A.A.S. ph (H 2 O) ph meter ph (Cacl 2 ) ph meter Type of Soil: Sandy-loam. Source: Soil Science Laboratory, University of Agriculture, Makurdi, Nigeria. ppm: parts per million. A.A.S.: Atomic Absorption Spectrophotometer. 484

4 Table 3. Yield performance of yam-minisett as affected by maize introduction dates during the 2003 and 2004 planting seasons. Establishment Leaf Frequency Tuber count of area index of tuber Number weight yam-minisett of yam-minisett twining of per plant Yield Dates of (No) at 120 DAP (No) tubers (g) (t/ha) maize Introduction Y+M (Same time) Y+M (3 weeks later) Y+M (6 weeks later) Means LSD(P=0.05) Cv (%) Y+M (Same time): Yam-minisetts planted same time as maize Y+M (3 weeks later): Yam-minisetts with maize introduced 3 weeks later Y+M (6 weeks later): Yam-minisetts with maize introduced 6 weeks later DAP: Days after planting 485

5 CONCLUSION From the results obtained, it can be concluded that for Makurdi location, Nigeria, the best tuber yield is obtained from yam-minisetts planted at same time as maize. This is associated with the greatest number of tubers, tuber weight per plant and tuber yield respectively. It is however recommended that further investigation be evaluated across Yield of yamminisetts as affected by maize introduction dates different locations with varied ecology within the Guinea savanna zone of Nigeria and across a wider combination of yam and maize varieties. ACKNOWLEDGEMENTS I thank the management of the University of Agriculture, Makurdi, Nigeria for the sponsorship of this study. I also thank the research technicians of the Department of Crop Production for their assistance in the field operations. REFERENCES Agboola, S.O. (2000). An Agricultural Atlas of Nigeria. Oxford University Press, Ibadan, Nigeria. Ekpete, D.M. (2000). Analysis of Responses to Fertilizer by Intercrops. Nigerian Agric J. 13: Kalu, B.A. and Ortese, J.T. (1993). Performance of White Guinea Yam (D. rotundata) Minisetts in Intercrop with Main Yam in the Nigerian Guinea Savanna. Agricultural System in Africa, 3(2): Kalu, B.A. and Erhabor, P.C. (1992). Production and Economic Evaluation of White Guinea Yam (D. rotundata P.) Minisetts under Ridge and Bed Production Systems in the Guinea Savanna Location. Trop Agric J, 69(1): Madu, F.O. and Nwosu, S.K. (2001). Effect of Fertilizer and Time of Interplanting Maize on the Performance of Yam-Maize Intercrop. Proceedings of the Second Annual Farming Systems Research and Extension Workshop in South Eastern Nigeria, Umudike, January 10-14, 2001, pp Okigbo, B.N. and Greenland, D.J. (1996). Intercropping Systems in Tropical Africa. In: Multiple Cropping. ASA Special Publication, No. 28, Madison, Pp Okoli, L.E. (2000). Climatic Effects on Field Crops. Proceedings of Agricultural Society, Nigeria, 12: Okonkwo, F.C. (2001). Studies in Intercropping. Journal of Agriculture, Food and Technology, 6: Osiru, S.O., Hahn, S.K. and Otoo, J.A. (1987). Outlook on Agriculture, 16(3): Steel, R.G.D. and Torrie, J.H. (1980). Principles and Procedures of Statistics, McGraw- Hill, New York. Unamma, U. P. (1999). Effect of Time of Interplanting Maize on the Performance of Yam-Maize Intercrop. Annual Farming Systems Research, Umudike, February 12-15, 2000, pp Uzozie, P.R. (2001). Effect of Time of Interplanting Maize on the Performance of Cassava-Maize Intercrop. J Agric Sci, 12: