Many of the research attempts made to revitalize agriculture especially our cropping systems in Nigeria and to create a sustainable rural livelihood have not given adequate emphasis to our traditional cropping systems and the land race legumes in particular. By means of diversification new in-roads have been made in the area of genetics and breeding and more recently in biotechnology of crop species especially the DNA marker-assisted crop improvement. However, not much effort has been made in improving the traditional farming systems using the landrace legumes, which exist in the cultivated and wild forms.
The advances made in agriculture in the past few decades have witnessed the
colonial research efforts on adapting some well known and highly researched
pulse species such as groundnut (Arachis hypogaea), soybean (Glycine
max (L.) Merr) and cowpea (Vigna unguiculata (L.) Walp) to high production
in the lowland humid belts with limited resources without any attempt on the
advancement of the landrace legumes. Our indigenous smallholder farmers who
produce majority of our food have not wholly adopted some of these exotic legumes
introduced into our farming environment. This poses serious challenge to researchers
in the humid tropics of Southeastern Nigeria because there are some landrace
legumes that could be upgraded through appropriate agronomic research. This
research tends to address this problem by intercropping these landraces with
yam; cassava based cropping systems to evaluate their performance. It is believed
that, these land races might even perform better than the exotic pulses. The
landraces are often preferred by our smallholder farmers due to considered fewer
production problems as they grow and yield well in the traditional age long
complex mixed cropping systems. These landraces include; the Lima bean (P.
lunatus L.) which locally is called Akidi-nwangwu, African yam bean
(Sphenostylis sternocarpa), locally called Okpa odudu, the velvet
bean (Mucuna pruriens var utilis) known locally as Agbiri and
are known to perform well in the highly leached infertile soils (Ultisols) of
Southeastern Nigeria. There has been limited research to identify their production
systems, potentials in nitrogen fixation, soil conservation and fertility and
documentation about their forage potentials. Also, there have been few trials
to improve these species as crop plants and more especially to explain the agronomy
required for their large-scale production either in sole or intercropping systems.
The lima bean is sporadically sown in mixed cropping systems after maize has
been harvested. The dry seeds are boiled and used for food in Nigeria. However,
it is a lesser-known legume crop in the low land tropics. Its intercropping
with vegetable crops in the tropics had been reported (Van
der Measeen and Sadikin, 1989). It is cultivated for its immature and dry
seeds like in Asia where the immature sprouts, leaves and pods are consumed
and because of its astringent qualities, is used as a diet for fever in traditional
Asian medicine and the dry bean is used to produce flour rich in protein in
the Philippines and also to enrich bread (Van der Measeen
and Sadikin, 1989).
The velvet bean (Mucuna pruriens) is a vigorously growing annual plant
that has a number of species and hybrids (Oudhia and Tripathi,
2001). It has trailing vine grown mostly for green manuring or temporary
pasture. The velvet bean is a perennial herbaceous climber mostly found in the
wild. It requires high temperatures and a humid climate but will grow on poor
sandy loams (Oudhia and Tripathi, 2001).
The African yam bean grown in several West African countries for their seeds
and tubers are not common and their cultivation is fast declining. In Nigeria,
the crop is known as Okpa Odudu or Girigiri. It belongs to the
family leguminoseae and sub-family papilliinoideae and can be seen in a variety
of ecological zones ranging from fertile highland areas to sandy leached areas
in the lowlands and also in swampy areas (Schippers, 2000).
The plant is a vigorous herbaceous vine that climb and twines to heights over
three meters with trifoliate leaves and leaflets being up to 14 cm in length
and 5 cm broad.
Yam production is an age long practice in West Africa and Nigeria in particular.
Yams rank second to cassava as the most important crop in Africa, In turn, Africa
accounts for nearly 98% of World yam production. A total of about 26 million
tones of yams are produced on the continent annually (Onwueme,
1989). This figure has almost doubled presently. According to a popular
Igbo saying, Yam was given to man by god and so believed to be closely linked
to the origin of mankind. Yam is part of the religious, social and cultural
heritage of many Nigerian tribes where yam still plays a key role in religious
ceremonies. In fact, it has been shown that most yam species originated from
West Africa (Onwueme and Sinha, 1991) hence yam is truly
an indigenous crop in the cultural and biological sense.
Maize has been involved in intercropping with many tuber and vegetable crops.
Maize/cassava intercropping system is popular with farmers in Nigeria (Ibeawuchi
and Ofoh, 2000). Maize (Zea mays L.) belongs to the family gramineae.
It is an annual monoecious plant and it is one of the most important agricultural
plants in the world. In many African countries, maize is the basic staple food
for subsistence farmers, miners and city dwellers.
Cassava is one of the principal plants of use to man because of the important
role it plays as food. It belongs to the Euphorbiaceae family the Manihot
gender and a dicotyledonous plant. It has numerous species but Manihot esculanta
has become of wide spread culture (Pierre, 1989). In Nigeria,
cassava is prepared as cassava fufu and served with vegetable soups. Boiled
cassava and cassava chips are eaten with coconut, groundnuts, fish or meat.
Salads made with cassava are usually well balanced and nutritious (Pierre,
It is believed that this study will fit well into the farmer oriented research programme currently adopted to benefit smallholder farmers that are predominant in the humid tropical zone of Southeastern Nigeria. These farmers are numerous and make a higher percentage of the farming population of Nigeria.
MATERIALS AND METHODS
The experiment was conducted at the teaching and research farm of the School
of Agriculture and Agricultural Technology, Federal University of Technology,
Owerri (FUTO), Nigeria; located between latitudes 5°23 8.7 N and longitudes
6°59 39.4 E at a height above sea level of 55 m (Hand held Global
positioning system). Owerri is in the tropical rainforest zone of southeastern
Nigeria which ecologicaly is characterized with more than 2500 mm annual rainfall,
27-29° annual temperatures and 89-93% relative humidity. The soils formed
from acid sands are classified as Ultisols (Eshett and Anyahucha,
1992). The Ultisols, (Acrisols in the FAO/UNESCO world soil map) are seriously
acidic, coarse textured, highly leached upland soils occurring further south
of the southeastern Nigeria. The soils have low mineral reserve and are, therefore,
low in fertility (Eshett, 1993).
Three landrace legumes endemic in the humid rainforest zone of southeastern
Nigeria were used namely: African yam bean-Sphenostylis sternocarpa;
Lima bean-Phaseolus lunatus and the velvet bean-Mucuna pruriens
var. utilis. Mucuna grows in the wild but the black seeds were collected from
the SAAT gene bank while lima bean and African yam bean were bought from the
rural markets in Owerri agricultural zone.
Other planting materials included: Cassava (TMS 30555); Yam (white) obiaeturugo-local cultivar; Maize-TZSR yellow. Cassava cuttings and maize were bought from the Imo ADP Headquarters along Okigwe road, Owerri.
For the repeat of the experiment in 2002, seed yams and cassava cuttings were got from the 2001 plantings while the saved 2001 maize were used.
Land preparation was done manually with machetes, spades and rakes since
minimum tillage was used. In each case, the site after clearing was left to
dry. The dry matter were later picked and removed from the site and thereafter
the field was marked out for planting.
The experiment was laid out in a randomized complete block design with 18 treatments replicated 3 times. This gave a total of 54 plots. Each plot measured 3x4 m with a space of 1m between each plot and 2 m between each block. There was a 1 m guard area round the experimental area, this gave a total of 1209 m2 or 0.121 ha. The treatments included sole crops of the individual crops and their combinations as follows:
Planting and Spacing
Planting was done in the first week of April 2001 as was also repeated in
2002. Seeds of the land race legumes were planted in holes at a depth of 2-5
cm at 50x50 cm spacing each. These were later thinned down to 1 per hole after
germination giving a plant population of 20,000 plants per hectare for sole
and intercropped plots of each of the three legumes.
Maize (TZSR-yellow), seeds were planted 2 per hole at a depth of 2-5 cm at 1x1 m spacing. This was thinned down after germination to 1 plant per stand giving a plant population of 10,000 plants per hectare.
Yam; Dioscorea rotundata (white) obiaeturugo local variety seed yams weighing 200-300 g were planted in holes measuring 30x30x30 cm at a spacing of 1x1 m on the flat. This gave a plant population of 10,000 plants per hectare.
Cassava (TMS 30555) cuttings measuring 20 cm long were planted on the flat at 1x1 m spacing giving a plant population of 10,000 plants ha-1.
No fertilizer or agrochemical was applied since the study involved legumes
for soil fertility enhancement.
The yams were staked as and when due. The land race legumes shared the same
stake with yam. In cassava-based system, the legumes utilized the cassava stems
as stake support.
Weeding was done 3 times with hoe at 4, 8 and 12 WAP for all the plots in
the experiment. In each case, the weed fresh weight was recorded.
Training of the yam and legume vines started immediately after staking and
continued up to 12 WAP.
Stand counts were taken from each plot before harvest was done.
Harvesting was done at the maturity of each test crop.
Dried maize cobs in the field were harvested at 15 Weeks after Planting
(WAP) when 99% of all the maize stands had dried. The cobs were sun dried and
dehusked, shelled and the grain weight was obtained.
African Yam Bean
The long pods of the beans ripened and dried at different intervals. Harvesting
of the dried pods were spread over a period of two weeks from 20-22 WAP. The
pods were further sun-dried and split open and the seeds collected. The seeds
were weighed with a Salter scale.
The dry pods of the bean ripened at different times. Harvesting was spread
over three weeks from 19-22 WAP. The pods were split, the seeds collected and
their weight obtained.
Velvet Bean (Mucuna pruriens)
The pods matured 17 WAP and drying started two weeks later. Harvesting of
the pods, which matured and dried at different intervals began from the 18 WAP
and lasted till 23 WAP. The pods were split open by applying some pressure with
a small stick. The black seeds were gathered and weight obtained.
The yams were harvest at 35 WAP with spade. The tubers were gathered and
weighed and the weight recorded.
The cassava stands were harvested at 60 WAP. The cassava cuttings were gathered
plot by plot at 20 cuttings/bundle. Cassava tubers per plot were weighed and
The data collected were collated and statistically analyzed using the Microsoft
Excel Packafe (2000) and SPSS (2004) packages. Wahua
1999 was used to help in data analysis and interpretation.
Maize Plant Heights (cm)
Results of Fig. 1 shows the maize plant heights (cm) as
affected by yam-based cropping systems. Results show that sole maize, yam/maize/lima
and yam/maize/African yam bean, had the highest maize plant heights that were
significantly different (p≥0.05) at 10 WAP from maize plant heights in Yam/Maize
and yam/maize/mucuna pruriens cropping systems. The maize heights at 3 and 7
weeks after planting were not significantly affected by the cropping systems.
Results indicated that there was uniformity in maize heights at 3 WAP (Fig. 2). However, at 7 and 10 WAP, the maize plant heights (cm) in all the other crop combinations were significantly higher (p≥0.05) than that in cassava/maize/mucuna crop combination.
Figure 3 showed that at 3 and 7 weeks after planting, there were uniform maize plant heights. However, at 10 WAP, sole maize, yam/maize/cassava/lima and yam/maize/cassava/African yam bean had the highest heights, which were significantly taller than the other maize plants in the crop mixture.
||Maize plant heights (cm); at 3, 7 and 10 weeks after planting
as affected by yam-based cropping system, 2001 and 2002. LSD (0.05) = 2.75
||Maize plant heights (cm), at 3, 7 and 10 weeks after planting
(WAP), As affected by cassava-based cropping system LSD (0.05) = 2.40
Cassava Plant Heights (cm)
Figure 4a shows the cassava plant heights (cm) as affected
by cassava-based cropping system. The data after analysis showed no significant
differences. Figure 4b shows the cassava plant heights (cm)
as affected by yam/cassava based cropping system. Also, there were no significant
differences in heights. However, from the Fig. 4a and b presented,
there are some noticeable differences in height 12 WAP, but statistically not
Effect of the Landrace Legumes on the Performance of Yam, Cassava-Based
Table 1 shows maize dry grain yields t ha-1
and stand count as affected by yam-based cropping system. The result shows that
in 2001, sole maize, yam/maize/lima, yam/Maize/African yam bean and yam/maize
gave high yields and were significantly higher (p≥0.05) than the yield from
||Maize plant heights (cm); at 3, 7 and 10 weeks after planting
as affected by cassava-based cropping system, 2001/2002. LSD (0.05) = 4.67
Also, in 2002, the sole cropped maize and the other crop combinations had higher
maize grain yield than yam/maize/mucuna cropping systems. Spearman coefficient
of rank correlation was performed to understand the relationship between yields
and stand count. In both 2001 and 2002 yield a high rank correlation with stand
count of 0.925 and 0.950, respectively were recorded.
Table 2 shows the maize dry grain yield t ha-1 and stand count as affected by cassava-based cropping system. The results show that in both 2001 and 2002 maize grain yield under sole cropping and cassava/maize/African yam bean and Cassava/maize were higher (p≥0.05) than that for cassava/ maize/mucuna. The Spearman coefficient of rank correlation was also high showing a close relationship between stand count and yield in both 2001 and 2002.
Table 3 shows the maize dry grain yield (t ha-1) and stand count as affected by yam/cassava-based cropping system. The results show that the maize yield in 2001 was higher than that for 2002 in yam/cassava-based cropping systems. However in both years, the sole cropping of maize and maize intercropped with yam/cassava and either Lima or African yam bean had higher grain yield than maize intercropping with yam/cassava/mucuna and were significantly different (p≥0.05). The Spearman coefficient of rank correlation of 0.950 and 0.527 were obtained in 2001 and 2002, respectively indicating a close relationship between stand count and yield.
Table 4 shows the mean fresh tuber yield (t ha-1) and stand count of yam (Dioscorea rotundata- local cultivar) as affected by the cropping system. The results revealed that the sole planted yam still had the full number of stand count per hectare. Also, there were no significant differences between the sole yam cropping, yam/maize/lima, yam/maize and yam/maize African yam bean in yam-based cropping system. But these were different significantly (p≥0.05) from yam/maize/mucuna and all yam based and in the yam/cassava-based cropping systems in both 2001 and 2002. The Spearman coefficient of rank correlation was not high especially in 2002 with 0.296.
Table 5 summarizes the data on fresh cassava tuber yield
(t ha-1) and stand count of cassava (TMS 30555) as affected by the
cropping system. Yields were generally high in both 2001 and 2002. However,
sole cassava cropping (18.25 and 16.61 t ha-1) cassava/maize/lima
(12.80 and 12.69 t ha-1), Cassava/maize African yam bean (13.03 and
15.89 t ha-1), yam/maize /cassava/lima (11.64 t ha-1)
and yam/maize/cassava/African yam bean 12.00 t ha-1) gave statistically
higher tuber yields than the other crop combinations.
||Cassava plant heights (cm), at 4, 8 and 12 weeks after planting
(WAP), as affected by cassava-based cropping system
||Cassava plant heights (cm), at 4, 8 and 12 weeks after planting
(WAP), as affected by yam/cassava-based cropping system
|| Maize grain yield (t ha-1) and maize stand count
as affected by yam-based cropping system
Also, the spearman coefficient of rank correlation 0.725 and 0.96 for 2001
and 2002, respectively between yield and stand count showed a close relationship.
|| Maize dry grain yield (t ha-1) and Maize stand
count as affected by cassava-based cropping system
|| Maize dry grain yield: t ha-1 and stand count
as affected by yam/cassava-based cropping system
||Mean fresh tuber yield (t ha-1) ans stand count
of yam (D. rotundata-local cultivar) as affected by the cropping
|| Mean fresh cassava root yield (t ha-1) and stand
count of cassava (TMS 30555), as affected by the cropping system
Table 6 shows the mean dry grain yield of the landrace legumes
(t ha-1) as affected by the cropping system. Results show that, in
both 2001 and 2002, yields of the sole legumes were higher than those in intercropping
systems at p≥0.05. Yields of sole Phaseolus lunatus and Sphenostylis
sternocarpa cropping and in intercropping with yam had higher yields and
were higher than those intercropped with yam/cassava-based mixture. However
the yields of Lima and African yam bean under cassava-based cropping system
did not show any significant differences between them compared with those of
yam-based and yam/cassava-based cropping systems.
|| Dry grain yield of the landrace legumes (t ha-1)
as affected by the cropping system, 2001/2002 cropping seasons
Maize Plant Heights (cm)
The non-significant effect of the maize heights at 3 and 7 WAP in yam-based
and yam/cassava-based cropping system could be as a result of little or no competition
for growth resources (light, water, nutrients) among the crops in the combinations.
Possibly the growth factors were in sufficient amount and were shared by the
different plant species (Ibeawuchi and Ofoh, 2000) in
yam-based and yam/cassava based cropping systems.
The morphology (canopy cover) of the associated crop species yam/maize/land
race legumes, cassava/maize/land race legume or yam/maize/cassava/landrace legumes
may have covered up after 7 and 10 WAP to initiate shading of the maize plant
within the new microenvironment. Since maize thrives well under high light intensity
(Ustimenko-Bakumovsky, 1983) and has high demand for soil
nutrients especially nitrogen (Onwueme and Sinha, 1991)
the canopy cover affected light interception with time, thus reducing the rate
of nutrient assimilation. Conover and Rex (1996) similarly
reported that plants grow slower in less optimum light and use less fertilizer
compared to when grown under optimum condition. It may therefore, be that as
the canopy cover becomes heavy in most plots of the trial, maize plants grew
slowly as a result of less nutrient uptake. This again depends on the extent
of shading that must have occured, since plants respond to environmental factors
such as periods of long or short day length, varying nutritional levels and
Cassava Plant Heights
Cassava plant heights were not affected by the cassava-based cropping systems
at 4, 8 or 12 WAP. The cassava Cultivar TMS 30555 had uniform heights at up
to 12 WAP. Such uniformity in height could be attributed to genetic make up
of the plant (Gardner et al., 1981).
Maize Grain Yield (t ha-1)
Inter-cropping maize with yam/Lima or African yam bean, cassava/lima or
African yam bean and yam/maize/cassava/lima or African yam bean did not significantly
depress maize grain yield in any of the two trial years. This is an indication
of the principles of complementarities of component crops as reported by Ibeawuchi
et al. (2005).
Yam Fresh Tuber Yield (t ha-1)
Yam yield was low and this low performance of yam could be attributed to
high number of component crops per plot coupled with heavy canopy cover of Mucuna
which resulted in shading of sun light in plots associated with mucuna. This
agreed with Onwueme and Sinha (1991) that the present
commercial yields of yam fall far below the potential yields obtainable as a
result of growing yams on poor soils.
Cassava Fresh Tuber Yield (t ha-1)
The significant differences obtained in cassava fresh root tuber yield among
the intercropping systems being higher in 2002 than in 2001 could be attributed
to changes in climatic and environmental conditions since uniform growth in
height was observed for the cassava 30555 in the two trial years. This agreed
with Ayoade (1993) who reported that any agricultural
system is a man made ecosystem that depends on climate to function just like
the natural ecosystem and that weather is the most important variable in agricultural
productions affecting crop yields. However, cassava had higher fresh root yields
in all the crop combinations with Lima and African yam bean than with Mucuna
Dry Grain Yield (t ha-1) of the Landrace Legumes
The Velvet Bean (Mucuna pruriens var. utilis). The Velvet Bean had
higher yields in sole cropping system (5.25 and 4.30 t ha-1) in 2001
and 2002, respectively. This was higher than what was reported by Peace Corps
(1990) of a yield average of 700 to 900 kg ha-1. However, the report
agreed with Singh et al. (1995) and Farooqi
et al. (1999) that grain yield of 5000 kg ha-1 have been
recorded from well managed irrigated crops having supports. This may be why
farmers preferred to grow Mucuna as a sole crop instead of inter-cropping it
(Mucuna News 2001, 1st Edn.).
The grain yield of Lima in pure stands was 0.63 and 0.64 t ha-1
in 2001 and 2002, respectively. For the yam based, cassava based and yam/cassava
based cropping systems the yields were 0.53, 0.44 and 0.37 t ha-1
in 2001 and 0.46, 0.55 and 0.26 t ha-1 2002. This report agreed with
Van der Measeen and Sadiku (1989) who reported a grain yield of 200-600 kg ha-1
throughout the tropics and observed that it may reach up to 2000-2500 t ha-1.
Also, the result agreed with Rice et al. (1990)
that yields of up to 1500 kg ha-1 dried bean may be obtained. However,
lima bean performs better in association with yam/maize, cassava/maize or sole
cropping than with yam/maize/cassava, cropping systems.
African Yam Bean
The grain yield of African yam bean planted sole performed better than those
intercropped. This could be as a result of its slow establishment in crop combinations
involving more than three component crops as observed by Ibeawuchi
and Ofoh (2003) that African yam bean could not compete effectively for
growth resources in highly combined crop components. However, the average yield
for sole cropping in 2001 and 2002 was 0.58 t ha-1 while 0.46, 0.43
and 0.25t ha-1 was recorded as average for yam based, cassava based
and yam/cassava based cropping systems respectively in the two trial year. The
range of the average yield of 0.43-0.58 t ha-1 agreed with the report
of 0.6 t ha-1by Ibeawuchi and Ofoh (2000).
There were high cassava root yield in the two cropping years for cassava-based crop mixtures and in yam based for 2001 cropping season. Yam and maize yields were depressed as a result of heavy canopy cover of mucuna due to shading effect and light interception, which helped in reduced photosynthesis and nutrient uptake, by the component crops. Farmers are encouraged to plant mucuna in plots and for proper use incorporate it into the soil for green manure to be followed by maize and yam cropping. This should be done year after year by planting mucuna at the harvest of maize when yam had already established. This will help improve the essential nutrient elements in the soil especially nitrogen since mucuna fixes large quantities of N in the soil. Researchers should gear efforts towards improving the three-landrace legumes genetically to make them candidate legumes for the lowland humid tropics. Finally, since the lima bean and African yam bean are already in use in our cropping systems by resource poor farmers, the farmers should be encouraged to cultivate mucuna for its numerous uses outside Nigeria.
Mucuna is a crop of the future therefore more effects should be placed on its research as human food and in health industries since it has found a place in the animal feed production industry as a replacement for energy and protein supplies.
We acknowledge Dr. Christopher Ugochkwu Akujuobi formerly of the Department of Agricultural Economics, Federal University of Technology Owerri for his contributions in the statistical analysis using his personal computer. Also we thank immensely Mr. C.I. Akaerue the Chief laboratory and Mr. Simon Nti of the Department of Soil Science Laboratory, Federal University of Technology, Owerri, Nigeria, for helping us in soil and plant tissue analysis during and after the experiments.