Yam Tuber Yield Research Articles

Effects of Organic And Inorganic Manures on The Yield Of Yam Tubers In Termite Infested Soils

A study on the effects of different organic and inorganic manures on the yield of yam tubers in termite infested soil of Owerri Imo State, South Eastern Nigeria was carried out at the Teaching and Research Farm of the Federal University of Technology, Owerri in 2004 and 2005 cropping seasons respectively. The soil was naturally infested with three types of termite genera, namely: Microtermes, Ancistrotermes and Macrotermes. The variety of yam used was Dioscorea rotundata (white yam) cultivar (cv.) Obioaturugo, planted in May 2004 and 2005 respectively. The experiments were laid out in a randomized complete block design (RCBD) with three replications. The treatments were poultry manure at 1.5 tons ha-1 (PMI) and at 3.0 tons ha -1 (PM2), pig slurry at 1.5 tons ha-1 (PS1) and at 3.0 tons ha-1 (PS2), municipal waste at 1.5 tons ha-1 (MW1) and at 3.0 tons ha-1 (MW2), NPK 15:15:15, NPKMg 12:12:17:2, NPK 20:10:10 each at 400kgha-1 and control (no manuring). Result showed that highest fresh tuber yield was recorded in plots where NPK 15:15:15 and NPK Mg 12:12:17:12 were applied in both years while the least was in control plots. Also in both years of the experiment, plots treated with organic manures generally gave lower fresh tuber yield than inorganic but showed marked reduction in termite damage especially with municipal wastes when compared with other treatments. Similarly, plots treated with organic manures gave higher soil pH after tuber harvest than inorganic manures. Keywords : inorganic manure, organic manure, termites, and tuber yield. International Journal of Agriculture and Development Vol. 9 2007: pp. 66-71

EFFECT OF POPULATION DENSITY AND SOWING DATE OF PUMPKIN ON SOIL HYDROTHERMAL REGIME, WEED CONTROL AND CROP GROWTH IN A YAM–PUMPKIN INTERCROP

Pumpkin (Cucurbita maxima) is used for live mulch and edible apical shoots, seeds and fruits, and requires that a strategy for using it as ground cover in intercropping with food crops be developed while sustaining reasonable apical and fruit yields. Field experiments were conducted in 1999–2001 to investigate the effects of population density (5000, 10 000 and 15 000 plants ha−1) and sowing date (March, April and May) of pumpkin on the soil hydrothermal regime, earthworm casts, weed control, and crop growth and yields in a Yam–pumpkin intercrop. Growing pumpkin between yam mounds reduced maximum diurnal soil temperature by 4.3–8.1 °C, weeding frequency by 52% and weed dry biomass by 50–67%, while soil moisture was conserved by 48–62 g kg−1, earthworm casts were increased by 58–68% and yam tuber yield by 30–52%, irrespective of population density or sowing date, compared with yam monoculture. Intercropping had no effect on the growth and fruit yields of pumpkin, but leaf area index and apical shoot and fruit yields increased by 30–49% as the plant population increased to 10 000 plants ha−1, beyond which there was no further significant increase. Furthermore, apical shoot and fruit yields were remarkably reduced when pumpkin was sown beyond April. Increasing pumpkin population up to 10 000–15 000 plants ha−1 reduced soil temperatures by 0.7–1.2 °C, weeding frequency by 15–35% and weed dry biomass by 36–57%, conserved soil moisture by 46–63 g kg−1, and increased earthworm casts by 20% compared to 5000 plants ha−1 in both cropping systems. Although the sowing date did not affect earthworm casts and weeding frequency, pumpkin sown in March or April reduced soil temperatures by 2.6–4.0 °C and weeds by 27%, and conserved soil moisture by 15–37 g kg−1, compared with May-sown plants. Intercropping pumpkin up to 10 000 plants ha−1 with yam at an optimal sowing date target in March-April is recommended for maximum development and productivity, and when pumpkin is used for live mulch in yam plots to reduce supra-optimal soil temperature, excessive evaporation and weed growth.

Performance of seven crop combinations in two soils of different land-use history in eastern Nigeria

Crop yields obtained from crop mixtures grown in a newly cleared virgin forestland were compared with those from a previously cultivated farmland to assess the crops' performance between the two sites with­out additional soil amendments. Generally a greater number of soil physicochemical properties were considered agronomically better in the forest than in the previously cultivated land. These soil properties may constitute the driving force for significantly (p£0.05) higher crop yields in the forestland and include: macroporosity, bulk density, saturated hydraulic conductivity, coarse sand content, pH, soil organic matter, total N, exchangeable acidity and Fe as well as base saturation. In both years, the high­est cassava root yields were obtained from either cassava + maize + pigeon pea or cassava + maize intercrops (not from sole cassava plots) even though the only significant (p£0.05) difference obtained was between cassava + maize + pigeon pea and all four crops combined, and at the cultivated farm­land (UNN farm) only. This suggests that it is even disadvantageous to grow cassava as a sole crop in the area. Cassava root yield reduction in 1999 relative to 1998 was higher (70%) in the UNN farm than in the forestland (40%). There was no significant difference due to crop combination on yam tuber yield in both locations in 1998. However, in 1999 sole yam plots gave significantly higher yields than cassava + yam + maize +pigeon pea plots. Increase in tuber yields was obtained in 1999 over 1998 in both locations but it was smaller ( Key words: Land use, soil properties, intercropping, land equivalent ratio Agro-Science Vol.2(2) 2001: 70-80

EFFECTS OF SIZE AND SPACING OF MINITUBERS ON YIELD OF THREE SELECTED YAM CULTIVARS IN THE HUMID TROPICS OF NIGERIA

Studies were conducted in 2000 and 2001 at Umudike Nigeria Umudike (50 27'N; 70 32'E) to determine the best spacing arrangement for growing minitubers for seed yam production. Three yam cultivars (D.alata cv UM 680) and D.rotundata (cv Abi and Obioturugo),3 intra-row spacings on 1m ridges (50cm, 75cm, 100cm) and three minituber sizes (50g, 75g 100g) were arranged in 3 x 3 x 3 split-split plot factorial arrangement of RCB design and replicated three times. D.alata minitubers(6.91 t/ha) gave significantly (p=1%) higher seed yam tuber yield than the other two cultivars of D.rotundata,(2.08 t/ha for Abi and 1.99 t/ha for Obioturugo) irrespective of size of minituber or spacing used The results suggest that 50g minitubers should be spaced either 50cm apart on 1m ridges (4.63 t/ha) or 100cm apart (4.95 t/ha) while the 75g minitubers could be spaced at any of the three spacings evaluated (50cm=4.79 t/ha; 75cm=4.37 t/ha and 100cm=4.95 t/ha). Similarly, the 100g minitubers should be spaced at 75cm (4.95 t/ha) or at 50cm (4.74 t/ha). [Niger Agric. J. 34 (2003): 58-62]

Comparative evaluation of the contributions of soil physicochemical properties to variations in the yields of four major staple food crops in eastern Nigeria

The contributions of soil variables to the variations in the yields of cassava ( Manihot esculenta), yam ( Dioscorea rotundata), maize ( Zea mays) and pigeon pea ( Cajanus cajan) were evaluated over 2 years in this study. The data were from three replicates of two randomized complete block design experiments sited in a newly cleared forest and on previously cultivated land both in Nsukka, eastern Nigeria. The 28 soil physicochemical properties and six crop yield parameters measured were partitioned between location and year before applying a stepwise regression procedure to analyze them. The study showed that soil variables accounted for >70% of the variation in cassava root yields and harvest index. Both soil physical and chemical properties contributed but the former (particularly macroporosity, microporosity, total porosity and bulk density) contributed most. Selected soil variables also accounted for >70% of the variation in yam tuber yield and shape index of tubers especially in 1998. In both crop years chemical properties appeared to dominate over the physical ones. Soil variables accounted for between 51 and 99% of the variation in maize grain and stover yields. The only exception was the figure of 44% obtained at the forest location in 1998. Soil pH, total exchangeable acidity and microporosity were particularly important contributors to the variations in both maize yield parameters. The contributions of soil variables to pigeon pea yield parameters were low (<50%) except in 1999 at the forest location where seven soil variables accounted for over 85% variation in seed yield. It was obvious generally from the study that soil variables were important determinants of yield variations in the four crops. It was also shown that physical properties should always be included in this kind of analysis. Also the number of soil variables which were of significance generally increased when the level of soil properties was low, as was the case with the cultivated site versus forest site, and 1999 versus 1998 analysis. Thus increasing the number of soil variables used and partitioning them into more homogeneous units helped to improve the results obtained using the procedure.

Production and energy-use efficiency of greater yam (Dioscorea a1ata)-based intercropping system as influenced by intercrops and planting patterns

A field experiment was conducted at Bhubaneshwar during 2001-02 and 2002-03 on acid laterite soils under rainfed conditions, to assess the production and energy-use efficiency of various greater yam (Dioscorea alata) based intercropping systems. Greater yam was planted at normal (90 x 90 cm), paired (601120 x 90 cm) and skipped rows (901180 x 90 cm) with 1,2 and 3 rows of maize (Zea mays L.), sorghum [Sorghum bicolor (L.) Moench] and pigeonpea [Cajanus cajan (L.) Millsp.] respectively as intercrop. Sole greater yam was planted as control. The maximum tuber-equivalent yield (18.7 tlha), land-equivalent ratio (1.37) and production efficiency (89.2 kglhalday) were obtained with maize as an intercrop in greater yam (normal planting), followed by greater yam (paired row planting). Pigeonpea and sorghum were the next best intercrops in the order. Similarly, intercrop- ping with normal row and paired row planting irrespective of intercrops produced higher output energy (84.25- 100.70 x 103 MJlha). Skipped row planting, due to lower greater yam tuber yield, recorded lower tuber-equivalent yield, land-equivalent ratio, production efficiency and energy output than sole greater yam cropping. However, en- ergy output : input ratio and energy-use efficiency of greater yam + pigeonpea in skipped row planting was highest due to its lowest seed as well as manures and fertilizers energy inputs. Greater yam + maize (normal row planting) intercropping system was the next best in energy output : input ratio due to higher energy from the yields. Thus, maize was the best intercrop (1 row) with greater yam planted at normal rows (90 cm x 90 cm).

Effect of time of mulching on soil temperature and moisture regime and emergence, growth and yield of white yam in western Nigeria

Time of mulching can influence the growth environment and performance of white yam ( Dioscorea rotundata Poir). An on-farm trial was conducted during the 1988–1989 and 1989–1990 seasons (October–August) in Nigeria to determine the effect of time of mulching (October–February) on the hydrothermal regime and emergence, growth and tuber yield of white yam. Application of 12.5 mg ha −1 of dry Eupatorium odoratum L. (Syn. Chromolaena odorata L.) mulch on top of the mounds significantly improved soil moisture content of the 15 cm surface layer by 50–120 g kg −1 and decreased the maximum soil temperature by 2–7°C at 15 cm depth in the early growing season (March–April). The emergence and development of yam seedlings were significantly lower in unmulched plots than in mulch-treated plots. Mulching significantly increased tuber yield by about 10–15 mg ha −1 season −1. Plots mulched in October–December were more moist by 20–60 g kg −1 and cooler by 1–3°C, and had 27–44% greater emergence than those mulched in January or February. The number of leaves per plant, vine diameter and leaf area index were also significantly greater in plots mulched in October–December than plots mulched in January or February. Consequently, shoot dry weight was about 28–36% greater in yam mulched in October–December than in yam mulched in February. However, the time of mulching had no effect on soil moisture of the surface layer at the beginning of the rainy season (April), on yam emergence in May and on tuber yield and yield components. Although time of mulching did not significantly affect tuber yield, the increase (10–15%) in the tuber yield of yam mulched in December–February compared to the yam mulched in October or November was considerable. It was concluded that yam planted in October, just before the rain stops, can be mulched in January or February without detrimental effect on emergence, growth and tuber yield.

Effects of tropical weeds on yield in white yam (Dioscorea rotundata Poir)

SummaryThe effects of tropical weeds on the yield of while yam were studied outdoors in wooden boxes. When the foliage and roots of weeds were in physical contact with the crop until harvest (full interference), tuber yield of yam was reduced by 76–79% of that obtained under weed‐free conditions over 3 years of study. When there was no physical contact between roots of crop and weeds, the leachate from the weed zone caused tuber yield reductions of 42, 40 and 38% in 1978, 1979 and 1980, respectively, when it was applied to the yam zone. This leachate also reduced leaf area index (LAI) in the yam crop but the adverse effects on yam root and shoot biomass were less pronounced. This technique made it possible to separate competitive interference from allelopathic interference of tropical weeds with the yam crop.

Effects of no-till and disc plowing with and without residue mulch on tropical root crops in southeastern Nigeria

Fields experiments were conducted on an Ultisol in southeastern Nigeria to study the effects of no-tillage and disc plowing, with and without residue mulching, on soil properties and the growth and yield of cassava and yam. Plowing to a depth of 10 cm and then applying mulch decreased soil bulk density. Of the no-till plots, those with mulch had the greatest soil moisture retention at low suctions; those without mulch had low moisture retention for suctions exceeding 0.1 bar. Cassava plants in plowed plots were more vigorous than those in no-till plots, and mulching decreased plant height of cassava in the initial stages and increased plant height at about 38 weeks after planting. In the first 10 cm, yam root length density was 0.31 cm cm −3 for no-till plots vs. 0.27 cm cm −3 for plowed plots. Mulch application increased root length density of yam. The root length density of cassava was 0.32 cm cm −3 for no-till plots versus 0.16 cm cm −3 for plowed plots. Mulch application, however, significantly increased root length density of cassava in no-till plots only. Yield of yam tubers was more for plowed plots than no-till plots — 12.4 vs. 10.9 t ha −1. The increase in yam tuber yield due to mulching was 21% for no-till and 28% for plowed treatments. The cassava tuber yield was more in no-till than in plowed plots, and application of mulch increased cassava tuber yield.

Influence of method of mulch application on growth and yield of tropical root crops in southeastern Nigeria

The effects of four methods of mulch application on growth and yields of yam ( Dioscorea rotundata) and cassava ( Manihot esculenta) were studied for an Ultisol at Onne, Port Harcourt, southeastern Nigeria. Treatments consisted of three different methods of applying 12 t ha −1 of dry mulch which were compared with an unmulched control. The three methods were complete surface mulch, row zone mulch and mulch incorporated in the top 10–15-cm layer with the second hoeing. Mulching had a significant effect on soil bulk density under cassava but not under yam. Application of mulch in the row zone and mulch incorporation in the top layer decreased soil bulk density of the 0–10-cm layer by 9 and 4%, respectively, in comparison with the unmulched control. The least infiltration rate, however, was observed for the mulch incorporated treatment due to formation of surface seal. During the dry season, the cumulative water loss from the soil was least for the complete surface mulch treatment. Soil chemical properties were also more favorable for complete surface mulch treatment. Density of feeder roots of cassava was high for the complete surface mulch and mulch incorporated treatments. Feeder root density of yam was lower than that of cassava and mulching had no effect. The highest tuber yield of yam was obtained for surface mulching. Cassava tuber yield, however, was not significantly affected by mulching.