Agricultural Science Digest

  • Chief EditorArvind kumar

  • Print ISSN 0253-150X

  • Online ISSN 0976-0547

  • NAAS Rating 5.52

  • SJR 0.156

Frequency :
Bi-monthly (February, April, June, August, October and December)
Indexing Services :
BIOSIS Preview, Biological Abstracts, Elsevier (Scopus and Embase), AGRICOLA, Google Scholar, CrossRef, CAB Abstracting Journals, Chemical Abstracts, Indian Science Abstracts, EBSCO Indexing Services, Index Copernicus
Submit

Full Research Article

Effect of Fruit Load on Seed Quality of Cowpea Varieties [Vigna unguiculata (L.) Walp. (Fabaceae)]

Any Olivier Komenan1,*, Adjoua Dorcas Kouakou2, Niambet Jean-Michel Koffi3, Mamadou Israël Diawara4, Kouamé Kévin Koffi4
  • https://orcid.org/0000-0003-1106-0976
1Jean Lorougnon Guédé University. Agroforestry Department. BP 150 Daloa, Côte d’Ivoire.
2Peleforo Gon Coulibaly University. Department of Biological Sciences. BP 1328 Korhogo, Côte d’Ivoire.
3National Centre for Agronomic Research, Bouaké (Côte d’Ivoire). Root and Tuber Crops Programme.
4Nangui Abrogoua University. Department of Natural Sciences. Unit of Phytotechny and Genetic Improvement. 02 BP 801 Abidjan 02, Côte d’Ivoire.

ABSTRACT

Background: The development of cowpea cultivation needs to be given priority because, in developing countries, cowpeas make up for many protein deficiencies. Producing quality seeds of this legume would be an essential objective if food security is to be achieved. This study aimed to establish the appropriate fruit load for optimum production of quality cowpea seed.

Methods: To achieve this, the impact of five different fruit loads (10, 20, 30, 40 and 50 pods per plant) on the yield of four cowpea varieties (KVx745-11P (V1), KVx775-33-2G (Tiligré) (V2), Gourgou (V3) and KVx780-6 (V4)) was assessed. The seeds’ germination capacity and the seedlings’ vigor were then assessed for each of the four varieties.

Result: Findings showed that seed length, width, thickness and weight changed significantly with increasing load in all varieties. The shortest time to emergence was recorded in the V1 variety for seeds from fruit loads of 20, 30, 40 and 50 pods per plant. For the ten pods per plant fruit load, the shortest emergence time was achieved with the V4 variety. The varieties V1, V2 and V4 studied produced excellent agronomic quality seeds when the pod was harvested with a load of 10 pods per plant. The fruit load significantly affected the seed quality and yield across all four varieties. Seeds from the minor C10 load for varieties V1, V2 and V4 and C20 for variety V3 exhibit high seedling vigour.

INTRODUCTION

Vigna unguiculata [L.] Walp. called cowpea is an important leguminous plants grown and consumed in tropical and subtropical areas of Africa, Asia, Europe and America (Taffouo et al., 2008). This legume has enormous agronomic and food potential. Compared to standard beans and soybeans, the principal interest of cowpeas is their heat resistance (Taffouo et al., 2008). It is a valuable source of protein, vitamins and minerals, making it an essential component of food security in developing countries (Dey et al., 2024; Kargiotidou et al., 2019).
       
According to FAO (2021), 8.9 million metric tons of cowpeas are produced yearly worldwide. In West Africa, cowpea accounts for 85% of the area under pulses and 10% of total cultivated land (Alene et al., 2006). In Côte d’Ivoire, cowpea remains a marginalized crop, despite its nutritional and cultural importance (N’gbesso et al., 2013). Production is around 36.310 tonnes/year, representing less than 2% of African production. In conventional cultivation, yields rarely exceed 500 kg of seed per hectare (Langyintuo et al., 2003). The low yields are a result of several constraints, including poor seed quality.
       
The seed is a productivity factor that alone could contribute to 40% of yield improvements (FAO, 2008). Quality seeds are necessary to meet food, nutrition and economic challenges. Thus, improving the living conditions of small producers through a sustainable increase in the performance of their farms requires implementing efficient seed systems that consider their needs (Djamen and Ouattara, 2017). Research has yielded significant results for yield improvement, but much remains to be done (Oumarou et al., 2017). It is in this perspective that the present study was initiated in the commune of Bédiala, Centre-West of Côte d’Ivoire, to set up a seed production system of acceptable quality, allowing rural producers to produce quality seeds.
       
The study aims to enhance food security by creating a technical process for producing high-quality cowpea seeds. More specifically, this study aims to determine the variety and the appropriate fruit load for good agronomic quality of cowpea seeds.

MATERIALS AND METHODS

Experimental site and plant material
 
The work was conducted by Nangui Abrogoua University, specifically in the West-Central Region of Côte d’Ivoire from 13 April 2022 to 29 July 2023.
       
Seeds from four different cowpea varieties (Table 1) were collected from the Institute for Environment and Agricultural Research (INERA) in Burkina Faso. Seeds used for germination tests were obtained after three months of cultivation (from April to June).

Table 1: Descriptions of the four cowpea varieties from INERA, along with their morpho-phenological characteristics.


 
Methods
 
The study of the fruit load was conducted on a completely randomized plot that included 20 boards of dimension 13 m x 6.25 m. The boards of 0.75 m equidistant plots comprised two lines of five seed sowing spaced 0.5 m apart. Each row was seeded with points that were 0.4 meters apart. The seeds were planted with two seeds per seed pot at a depth of 3 cm. Then, a dismarriage was carried out at the five-leaf stage, leaving only one vigorous plant per seed sowing. In total, 200 plants were retained. Five levels of fruit loads have been pre-defined for this study: specifically, 10, 20, 30, 40 and 50 fruits per plant. Once a given plant’s desired fruit load level was reached, new flowers were systematically eliminated until the retained fruits matured. This elimination was done manually by destroying the flower buds.
       
A completely randomized experimental plot was used for germination tests. This plot contained 20 boards of 0.6 m x 0.45 m each. The ploughed and levelled boards had 20 seed points, each equidistant 10 cm. For germination tests carried out on the four varieties of cowpea (V1, V2, V3 and V4), seeds in good physical and sanitary condition from five fruit load levels (10, 20, 30, 40 and 50 pods/plant) were used.
 
Data collection and analysis
 
Seventeen agro-morphological parameters were evaluated in this study (Table 2). These result from several previous works (Vaggar et al., 2022). For each variety, a batch of 10 pods and five seeds randomly selected per plant were selected for each fruit load for the eight yield parameter measurements. Vigor and viability were assessed regarding seed germination and normal seedling production (Egli and Tekrony, 1995) on three weeks after planting.

Table 2: Cowpea variety evaluation parameters and measurement methods.


       
An initial multivariate analysis of variance (MANOVA) was conducted to evaluate the significance of the overall effects of variety and fruit load on various agro-morphological parameters. ANOVA tests were performed to compare the means of each parameter against each other based on the factors considered. When a significant difference (P< 0.05) has been observed at the risk level α=0.05, the Kruskal-Wallis test was used. The data collected was analyzed using R version 4.2.1.

RESULTS AND DISCUSSION

Evaluation of yield parameters based on fruit load
 
Overall effect of factors on performance parameters
 
Multiple variance analysis (MANOVA) showed a very significant influence (P<0.001) of variety, fruit load and their interaction (fruit load variety) on yield parameters (Table 3). Therefore, only the effect of the interaction was considered for analysis and interpretation of results. The analysis of variance (ANOVA) revealed that the combination of fruit load and variety leads to better performance of the evaluated yield parameters.

Table 3: MANOVA results demonstrate the significant impact of fruit load, cowpea variety and their interaction on yield parameters.


 
Combined effect of fruit load and variety on yield parameters
 
The analysis of variance (ANOVA) showed that the variety load interaction had a highly significant influence (P< 0.001) on the evaluated yield parameters (Table 4). According to the Kruskal-Wallis test, high fruit weight (PFr), number of seeds per fruit (Ngr/Fr), weight of seeds per fruit (Pgr/Fr), weight of seed (Pgr), length of seed (Lgr) and seed thickness (Egr) and low values at the seed width (lgr) and weight of 100 seeds were observed in seeds from the C20 fruit load. The average observed shows that V2 varieties recorded the highest fruit weights (PFr) at 20 pods per plant (C20) and 30 pods per plant (C30). The fruit load affected the number of seeds per pod (Ngr/Fr) and the highest value was obtained with the V1 variety at 20 pods per plant (C20) and 50 pods per plant (C50). As for the weight of seeds per fruit (Pgr/Fr), the most important value was obtained in the V3 and V4 varieties at the C20 load. About the weight of the seed (Pgr) and the length of the seed (Lgr), the variety V4 recorded the maximum values at load C10. For seed width (lgr) and seed thickness (Egr) the V2 variety recorded maximum values at loads of 30 pods and 50 pods per plant. The V3 variety recorded the highest weight of 100 seeds (P100) for the C50 load.

Table 4: Effect of fruit load × cowpea variety interaction on yield parameters.


 
Assessment of vigor and viability parameters based on fruit loads
 
Overall effect of factors on vigor and sustainability parameters
 
The multiple variance analysis (MANOVA) revealed a highly significant (P<0.001) impact of variety and fruit load factors, as well as their interaction (fruit load variety) on seed vigour and seedling viability (Table 5). Only the variance analysis (ANOVA) based on the fruit load variety interaction was performed to elucidate the combination of fruit load and variety that leads to a better performance of the vigor and viability parameters studied. 

Table 5: Result of MANOVA indicating the overall effect of factors on vigor and viability parameters.


 
Combined effect of fruit load and variety on seed viability
 
The analysis of variance (ANOVA) indicates that the fruit load and variety interaction showed a highly significant influence (P<0.001) on all viability parameters. The Kruskal-Wallis test indicated that variety V1 had high values for crop loads C10, C20, C40 and C50. However, for the C30 load, the highest value was obtained by the variety V2. The V3 variety achieved its best potential for viability at the C20 load. The best potential for viability of V4 is obtained at C20 and C40 (Table 6).

Table 6: Average values of seed viability parameters for cowpea based on fruiting loads and variety.


 
Combined effect of fruit load and variety on plant vigour
 
The ANOVA revealed a highly significant influence (P< 0.001) of the fruit load variety interaction on all parameters of seedling vigor (Table 7). The V1 variety recorded the lowest values for plantlet height (HaP: 23.42 mm), leaflet length (LFo: 9.53 mm), leaflet width (lFo: 3.91 mm), leaf surface (SFo: 25.06 mm) and collar diameter (Dcol: 2.81 mm) in seeds from the fruit load of 30 pods per plant (C30). Conversely, higher values (LFo: 14.35 mm; lFo: 5.38 mm; SFo: 49.34 mm; Dcol: 5.84 mm) respectively of these parameters were obtained with the seeds of the V4 variety for the C10 load, with a high value of plant height (HaP: 41.2 mm). For the V2 variety, the highest values of plant height, leaflet length, leaf area and collaring diameter were observed at load C10, while for these same parameters, the V3 variety performed best with a C20 load (Table 7). These results related to young plant vigour revealed that the V1 variety has the lowest values. The highest load is C10 with the varieties V2 and V4.

Table 7: Mean Value±standard deviation of vigor parameters under the influence of fruiting load and cowpea variety interaction.


       
High-quality seed production is crucial for ensuring food security, especially for directly seeded plants (Copeland and McDonald, 2001). The study aimed to assess how fruit loading affects seed quality in four cowpea varieties. The species or variety of a plant, the treatments applied and the timing of application can influence its morphological and phenological behavior (Chaves et al., 2002). To this end, the study showed that seed treatments applied to cowpea varieties affected them both quantitatively and qualitatively.
       
All yield parameters recorded for the four cowpea varieties were influenced by fruit load. To this end, work has shown that the resulting fruit is significant when the load is reduced (Choi et al., 2010). In this fruit load study, the expression of yield parameters under the effect of applied fruit loads differed for each variety. For instance, at the lowest plant load (C10) at the load (C20) and the load (40), the V4 variety produced the most giant seeds (length, width and thickness) of seeds and average weight of seeds. At C30 and C50 the variety V2 presented larger seed sizes. The V1 variety has small seed sizes from the lowest (C10) to the highest (C50) plant load, while the V3 variety has intermediate-sized seeds. This agronomic potential inherent to each variety could result from genetic factors. Pod size, seed size, weight of 100 seeds and number of seeds per pod in cowpeas are highly heritable genetic traits (Khanpara et al., 2016; Singh et al., 2016; Amusa et al., 2019).
       
Based on our results analysis, the fruit load interaction influenced all yield parameters. Except for the number of seeds per fruit and the weight of 100 seeds, which did not show a regular evolution, the average values of the length, width and thickness of the seed and the average weight of the seed tended to decrease linearly with the increase in fruit load for all varieties. Indeed, the higher C50 load indicates a decrease in size (length, width and thickness) and weight of seeds per fruit. This may mean that the more fruit a plant bears, the less resources it has to provide for seeds (Kumari et al., 2020). These results show that a reduction in fruit load per plant is compensated by producing large seeds with a high average weight for all varieties. This would likely result from the fact that the threshold load at which resources become a limiting factor has not been reached. The fruitful profile indicates that the weight of 100 seeds was higher in fruits with lower seed yield. This result may be attributed to the fact that early harvest densities during the fruit cell growth period may decrease fruit growth rate, affecting carbohydrate availability and reducing final fruit size. These data indicate that seed production requires a variety-specific fruit load for improved yield.
       
The fruit load treatment significantly affected the average germination time, germination rate, emergence time and emergence rate.  According to Moravcova et al., (2005), this phenomenon is related to the quantity of nutrient resources in seeds. The number of seeds in fruits affects their nutrient mobilization and can increase seed germination capacity (Marcelis and Hofman-Eijer, 1997). The amount of reserves accumulated in seeds is essential when a fruit contains a high number of seeds. The high viability of V1 seed from treatments is due to many available resources in the V1 seed. However, the low viability of V3 seeds from C10, C20, C30 and C50 treatments is due to a small amount of available resources in these seeds at these treatments. We find a variation when we observe the impact of the variety load interaction on the plant vigor parameters. Seeds from the minor C10 load for varieties V1, V2, V4 and C20 for variety V3 have high seedling vigor. Beyond this specific load, the seeds of all four varieties produced seedlings of relatively low vigor.
       
These results suggest that a load optimum linked to each variety would allow the production of quality seeds capable of producing seedlings with greater vigor at emergence. Higher load levels than this optimum would, therefore, lead to seeds whose quality at maturity would negatively affect the vigor of seedlings at emergence.

CONCLUSION

Our focus was to assess the impact of fruit load on the seed quality of four cowpea varieties to determine the most suitable harvest stage. In conclusion, the fruit load significantly affected the seed quality and yield across all four varieties. The varieties V1, V2 and V4 studied produced excellent agronomic quality seeds when the pod was harvested with a load of 10 pods per plant. Seed viability and seedling vigor changes were closely related to seed weight. Thus, the weight of harvested cowpea fruit is a reliable indicator for seed selection and is closely related to the stage of maturation.

ACKNOWLEDGEMENT

The study was supported by the African Union funds and implemented by three African institutions: Université Nangui Abrogoua University (UNA) in Côte d’Ivoire, Bangui University (UB) in Central Africa and the Institute for Environment and Agricultural Research (INERA) in Burkina Faso.

DISCLAIMERS

The views and conclusions expressed in this article are solely those of the authors and do not necessarily represent the views of their affiliated institutions. The authors are responsible for the accuracy and completeness of the information provided, but do not accept any liability for any direct or indirect losses resulting from the use of this content.

INFORMED CONSENT (WE WORK ON PLANT MATERIAL)

All animal procedures for experiments were approved by the Committee of Experimental Animal care and handling techniques were approved by the University of Animal Care Committee.

CONFLICT OF INTEREST

The authors declare that there are no conflicts of interest regarding the publication of this article. No funding or sponsorship influenced the design of the study, data collection, analysis, decision to publish, or preparation of the manuscript.

REFERENCES


  1. Alene, A.D. and Manyong, V.M. (2006). Farmer-to-farmer technology diffusion and yield variation among adopters: the case of improved cowpea in northern Nigeria. Agricultural Economics. 35(2): 203-211.

  2. Amusa, O.D., Ogunkanmi, A., Adetumbi, A., Tayo, A. and Ogundipe, O. (2019). Morpho-genetic variability in F2 progeny cowpea genotypes tolerant to Bruchid (Callosobruchus maculatus). Journal of Agricultural Sciences. Belgrade. 64(1): 53-68.

  3. Chaves, M.M., Pereira, J.S., Maroco, J., Rodrigues, M.L., Ricardo, C.P.P., Osório, M.L. and Pinheiro, C. (2002). How plants cope with water stress in the field? Photosynthesis and growth. Annals of Botany. 89(7): 907-916.

  4. Choi, J.H., Law, M.Y., Chien, C.B., Link, B.A. and Wong, R.O. (2010). In vivo development of dendritic orientation in wild-type and mislocalized retinal ganglion cells. Neural Dev. 5(1): 29.

  5. Copeland, L.O., McDonald, M.B., Copeland, L.O.and McDonald, M. B. (2001). Seed vigor and vigor testing. Principles of Seed Science and Technology. pp. 165-191.

  6. Dey, J.K., Debnath, A., Das, P., Sarkar, S., Das, R., Chakraborty, A., Mandal, A.K. and Debbarma, P.  (2024). Energy Budgeting and Economic Analysis of Cowpea Varieties under Rainfed Condition. Legume Research. doi: 10.18805/LR-5251.

  7. Djamen, P. and Ouattara, S. (2017). Secteur semencier au Burkina Faso: Recommandations pour une meilleure intégration des producteurs.Technical Report. pp 39.

  8. Egli, D.B. and Tekrony, D.M. (1995). Soybean seeds germination, vigor and fiel emergence. Seed Science and Technologiy. 23(3): 595-607. 

  9. FAO. (2008). L’état de l’insécurité alimentaire dans le monde. http:/ /www.fao.org/3/a-i0291f.pdf.

  10. FAO. (2021). Crop Production and Trade Data. http://www.fao.org/ faostat/en/#data/QC. (accessed April 15, 2021).

  11. Kargiotidou, A., Papathanasiou, F., Baxevanos, D., Vlachostergios, D.N., Stefanou, S. and Papadopoulos, I. (2019). Yield and stability for agronomic and seed quality traits of common bean genotypes under Mediterranean conditions. Legume Res.-An Intern. J. 42: 308-313.

  12. Khanpara, S.V., Jivani, L.L., Vachhani, J.H.and Kachhadia, V.H. (2016). Genetic variability, heritability and genetic advance studies in vegetable cowpea [Vigna unguiculata (L.) Walp.]. Electronic Journal of Plant Breeding. 7(2): 408-413.

  13. Kumari, R., Hamal, U. and Sharma, N. (2020). Resource Allocation in Flowering Plants: Concept and Implications. In: Tandon, R., Shivanna, K., Koul, M. (eds) Reproductive Ecology of Flowering Plants: Patterns and Processes. Springer, Singapore. pp 157-171. 

  14. Langyintuo, A.S., Lowenberg-DeBoer, J., Faye, M., Lambert, D., Ibro, G., Moussa, B.and Ntoukam, G. (2003). Cowpea supply and demand in West and Central Africa. Field Crops Research. 82(2-3): 215-231.

  15. Marcelis, L.F.M. and Hofman-Eijer, B.L.R. (1997). Effects of seed number on competition and dominance among fruits in Capsicum annuum L. Annals of Botany. 79(6): 687-693.

  16. Moravcova, L., Perglová, I., Pys¢ek, P., Jaros ¢ík, V. and Pergl, J. (2005). Effects of fruit position on fruit mass and seed germination in the alien species Heracleum mantegazzianum (Apiaceae) and the implications for its invasion. Acta Oecologica. 28: 1-10.

  17. N’Gbesso, F.D.P.M., Fondio, L., Dibi, B.E.K., Djidji, H.A.and Kouamé, C.N. (2013). Étude des composantes du rendement de six variétés améliorées de niébé [Vigna unguiculata (L.) Walp]. Journal of Applied Biosciences. 63: 4754-4762.  

  18. Oumarou, H.I., Soumana, B., Toulou, A.and Yamba, B. (2017). Evaluation des rendements en graines et fanes des variétés améliorées et locales de niébé [vigna unguiculata (L.) walp.] en champ école et en champ de multiplication de semences à KARMA (NIGER). Agronomie Africaine. 29(1): 19-27.

  19. Singh, A., Singh, Y.V., Sharma, A., Visen, A., Singh, M.K.and Singh, S. (2016). Genetic analysis of quantitative traits in cowpea [Vigna unguiculata (L.) Walp.] using six parameter genetic model. Legume Research-An International Journal. 39(4): 502-509. doi: 10.18805/lr.v0iOF.10285.

  20. Taffouo, V.D., Etamé, J., Din, N., Nguelemeni, M.L.P., Mounga, Y., Eyambé, R.F.T.and Akoa, A. (2008). Effets de la densité de semis sur la croissance, le rendement et les teneurs en composés organiques chez cinq variétés de niébé [Vigna unguiculata (L.) Walp]. Journal of Applied Biosciences.  12: 623-632.

  21. Vaggar Sanjeev, Kumar Udit, Prasad K., Yadav L.M., Pramila, Sinha B.M. (2022). Study of Genetic Divergence for Yield and Quality Traits in Cowpea [Vigna unguiculata (L.) Walp.]. Legume Research. 45(4): 410-414. doi: 10.18805/LR-4297.
Reviewed By

Download Article
In this Article
    Contact us
    Follow us

    Editorial Board

    View all (0)