Ethnobotanical Leaflets 11: 113-121. 2007.

Characterization Studies and Yield Attributes of Some Varieties of Cowpea (Vigna unguiculata L.)

Alege, G. O. and Mustapha, O. T.*

Department of Plant Biology, University of Ilorin, Ilorin, Nigeria

*Corresponding Author: Oba Mustapha

Issued 8 June 2007

ABSTRACT

Investigations were carried out on sixteen improved varieties of cowpea (Vigna unguiculata L walp) obtained from International Institute for Tropical Agriculture, Ibadan. These varieties were grown in the Department of Biological Sciences Garden, of the University of Ilorin. Qualitative and quantitative characters were observed for the study. Positive correlations were obtained between leaf number and stem diameter, leaf number and number of seeds per pod, number of branches and plant height. Negative correlation existed between number of pods per plant and number of seed per pod. Analysis of variance (ANOVA) showed significant difference in all the quantitative characters analyzed among the varieties. Each character was also analyzed using Duncan test and F-LSD. The result showed that IT99K-529-1, IT99K 429 2, IT97K 461 4, IT98K 506 1 and IT99K- 1122 were outstanding in term of vegetative and yield performances in Ilorin, Kwara State of Nigeria

INTRODUCTION

Differences between individual organisms have two causes: variation in the genetic material which all organisms possess and which is passed from generation to generation; and variation caused by environmental influence on each individual organism (Elrod and Stansfield 2003). Heritable variation is the raw material for both natural and artificial selection and is ultimately therefore the basis for all observable biodiversity. Genetic diversity is particularly important for agricultural productivity and development (Fadconer, 1989).

Cowpea contains about 25% protein, making it extremely valuable where many people cannot afford protein food such as meat and fish (IITTA 2002). Hall (2003), Ogbuiya (1997) and Adams (2003) also reported on the various uses to which different parts of cowpea can be put to. As reported by IITA (2002), the fast growth and spreading habit of traditional cowpea ensures maturity at the end of the rainy season, spreading the harvesting operation overtime and enable better and efficient use of family labour.

Johnson et. al. (1955) reported that it is very important in any breeding programme to select and evaluate varieties for quantitative and yield ability before such varieties can be introduced to a given local environment. The aim of this work is, therefore, to characterize these improved varieties and evaluate the yield with a view to determining the best variety(ies) for introduction into the locality where the experiment was conducted.

MATERIALS AND METHODS

Sixteen different improved varieties of cowpea (Vigna ungiculata) seed were obtained from International Institute for Tropical Agriculture (IITA), Ibadan Nigeria. The accessions ascribed on the sixteen varieties from IITA were used.

The work was carried out on a plot of land in the Biological Garden of the University of Ilorin Permanent site. Clearing was done and sixteen beds were made. Planting was done in a randomized block manner. Three rows of five columns were made for each treatment giving fifteen plant stands per bed. Three seeds were sown per hole at about 3cm deep. Spacing of 30 cm between rows and 20 am between column was maintained for each variety. Each seedling stand was reduced to two seedlings per stand and beds were labeled accordingly to avoid confusion during the study. Weeding was done twice within the first five weeks of planting after which the crops can compete favourably with in its environment. The crops were sprayed with pesticide, cypermethrin (Karate) made to a solution of 0.2ml per 150ml of water. Spraying was done using a hand sprayer with spraying nozzle. Spraying was done two weeks after planting and subsequent application was done at two weeks interval until flowering begins when the spraying was reduced to weekly application. Quantitative characters studied are plant height, numbers of primary branches per plant, maturity period, stem girth, number of leaves per plants, pod length, pod circumference, number of pods per plant, number of seeds per pod, seed weight. Qualitative characters studies were fruit colour, seed colour, leaf shape and size, seed shape, flower colour and hairiness of different parts. Pollen viability test was conducted by collecting mature flower of each variety from the plants, pollen grains from each variety were dusted on a clean glass slide and a drop of methylene blue stain was introduced onto the slide and covered with clean coverslip and focused under a microscope. In each case, at least 400 pollen grains were counted and the percentage pollen viability of each variety was determined. The values obtained were subjected to Analysis of variance (ANOVA), Duncan multiple test and Fishers Leaf significant Difference Test (F-LSD).

RESULTS AND DISCUSSION

Table 1 shows coefficient of variation for characters studied and it was observed to be high for number of branches per plant, number of leaves per plant, number of seeds per pod and number of pod per plant ie. 34.13%, 34.00%, 31.61% and 31.21% respectively. This implies that the varieties were different from one another in terms of leaves, branches, seed and pod producing ability but low coefficient of variation was observed for characters such as pod length and pod diameter (13.10% and 12.28% respectively). The finding agrees with Wien and Ackahs (1978) conclusion. Result of qualitative characters studied showed that there are differences among the cowpea varieties (Table 2). This indicates that these varieties were of distinct genotype. Dulley and Moll (1969) stated that varieties of different qualitative characters are of distinct genotype and may breed for the manifestation of different traits in crop improvement.

Correlation Coefficient (Table 3) showed that there is a strong positive correlation between leave number and stem diameter and also a positive correlation between leaf number and number of seeds per pod. This implies that the more the number of leaves, the wider the stem girth and the more the number of seeds produced per pod on each plant. There also exists positive correlation between number of branches and height. According to Falconer (1989), the phenotypic variability of quantitative traits in a population usually has an environmental component. So, it is inferred that those characters with positive correlations are influenced and controlled by similar gene combinations and environmental factors.

There existed a negative correlation between pod number and number of seeds per pod. This implies that the more the pods on a plant, the less the number of seeds in a pod. So improvement on number of pod may contribute adversely to the number of seeds in such pods. This is in line with Dhagat et. at. (1978) who opined that negative genotypic correlation between characters selected for in breeding programme may result in reduction in the rate of improvement that could be attained if the correlation were positive or non-existing.

Analysis of variance table showed that there are significant differences in all the characters studied among the varieties. This is an indication that genetic variability existed for all the quantitative characters analyzed. This is because the basis of any crop improvement is the availability of genetic variability within a population (Henry 2004).

Multiple comparison for all the vegetative characters studied have shown that IT99K 1122 had the highest means for three out of the four vegetative traits analyzed i.e height of plant, leaf number, and number of branches. IT99K 429-2 had highest stem diameter (Table 4). This shows that these varieties (IT99K-1122 and IT99K-429-2) are the most adapted in term of vegetative performance in the environment of study. Faluyi (1978) stated that cowpea varieties with better vegetative characters can be used in the tropics for controlling erosion and as animal feeds. IT99K-316-2, which had the least mean values for leave number and stem diameter, is the least adapted variety in term of vegetative characters. These two varieties are recommended if the purpose of planting is for their vegetative parts.

IT97K-461-4, IT98K-506-1, IT99K-529-1 and IT99K-1122 had highest mean values which were significantly different from every other variety in term of pod number, pod length, pod diameter and seed per pod respectively (Table 5). This indicated that the four varieties were of outstanding performance in term of yield attributes. IT 99K-1122, though had least mean number of pod per plant, it distinguished itself by been significantly different from others in term of mean member of seeds per pod.

In conclusion, this work revealed the existence of genetic variability among the sixteen improved cowpea varieties studied. The work has also helped to select, evaluate and indicate those varieties that were of best performance in terms of quantitative and quantitative traits studied. Of all the sixteen varieties of cowpea used in this work, IT97K-461-4, IT99K-529-1, IT99K-429-2, IT99K-1122 and IT98K-506-1 were quite outstanding and thus, these varieties were recommended for cultivation in this part of Nigeria because they will perform better than other varieties studied.

REFERENCES

Adams, M.W. (2003) Beans/cowpea collaborative Research support, Program, Field Crops Res. 8:81-85.

Dhagat, N.K. Goswami, U and Inghani, V.G. (1978) Genetic variability, character Correlation and path analysis in Barnyard Millet, Indian Journal of Agricultural Science 48(4): 211-214.

Dulley, J. W and Mol, R. H (1969) Interpretation and uses of estimates of heritability and genetic variability in plant breeding. Crop science, 9:257-262

Elrod,s. L.a nd stanfield W.D (2003) Genetics: Tata mcGram hill publication, New Delhi. India.

Falconer, D. S. (1989) Introduction to Quantitative Genetic, 3^rd ed. Longman Science and technical. England.

Faluyi, M. A. (1987) Investigation on the relationship between yield and vegetative traits in cowpea in a tropical rainforest environment. Nigeria Journal of Agronomy 2(2): 55-60.

Hall, A. E. (2003) future directions of bean/cowpea Collaborative research program. Field crops Res. 82:233-239.

Herry, R,J. (2004) plant diversity and correlation: genotypic and phenotypic variations In higher plant: edit by Wallingford: CABE publishing, New York.

IITA (2002) Cowpea in sub-Sahara Africa: Ibadan, Nigeria. IITA.

Johnson, H.W, Robinson, H. F. and Comstock, R. E. (1955) Genotypic correlation in Soyabean and their implication in selection. Agronomy Journal 47:477-485.

Ogbuiya, P. O. 1997) Advances in cowpea Research. Biotechnology and Development Monitor 33:1012-1018.

Wien, H. C. and Ackah, E. E. (1978). Pod development period in cowpeas: Varietal differences and related to seed characters and environmental effect, Crops science 78:791-794.

CV- means Coefficient of Variation

NL - Number of Leaves Per Plant

NB - Number of Branches Per Plant

PH- Plant Height At Flowering

SD - Stem Diameter

PL - Pod Length

PP - Number of Pod Per Plant

PD - Pod Diameter

SP - Number of Seeds Per Pod

LEAVE

BRANCH

STEM

HEIGHT

POD

PODIAMET

SEED

PODLENGT

LEAVE Pearson Correlation

P. Value

No of Observation

1.000

80

.720

.000

80

285+

.010

80

367+

001

80

.216

.054

80

.349+

.002

80

.261+

.019

80

.062

.584

.80

BRANCH Pearson Correlation

P. Value

No of Observation

.720*

.000

80

1.000

80

169

134

80

278+

.013

80

.065

.566

80

.207

.066

80

.125

.268

80

.189

.094

80

STEM Pearson Correlation

P. Value

No of Observation

.285

.010

80

.169

.134

80

1.000

80

325+

.003

80

.015

.895

80

.041

.590

80

.061

.590

80

167

139

80

HEIGHT Pearson Correlation

P. Value

No of Observation

.367*

.001

80

.065

566

80

325+

003

80

1.000

80

.080

.482

80

.090

.429

80

.090

.429

80

.095

.403

80

POD Pearson Correlation

P. Value

No of Observation

.216*

.054

80

.005

566

80

.015

895

80

.080

482

80

1.000

80

.224+

.046

80

.224+

.046

80

.006

.957

.80

PODIAMET Pearson Correlation

P. Value

No of Observation

.349*

.002

80

207

.096

80

.041

717

80

088

438

80

.210

.002

80

.300+

.007

80

.300+

.007

80

.085

.467

.80

SEED Pearson Correlation

P. Value

No of Observation

.261

.019

80

125

268

80

.061

590

80

090

429

80

.224+

.046

80

1.000

.007

80

1.000

80

.151

.183

.80

PODLENGT Pearson Correlation

P. Value

No of Observation

.062

.584

80

189

268

80

167

139

80

095

403

80

.006

.957

80

.083

.462

80

.151

.183

80

.080

+

80