[01] John Ochoche Okoh, Department of Plant Breeding and Seed Science, University of Agriculture, Makurdi, Makurdi, Nigeria. [02] Sunday Adesola Ajayi, Department of Crop Production and Protection, Obafemi Awolowo University, Ile-Ife, Nigeria.

The experiment was carried out in early and late cropping seasons of 2012 at the Teaching and Research Farm of the Obafemi Awolowo University Ile-Ife to determine the effect of season of production, and harvest date (HD) on cowpea seed quality. Three varieties of cowpea namely; IfeBPC, TVX3236 and IT97K-499-35 were used for the study. Seed production was carried out at the University’s Teaching and Research Farm. Pods were harvested from seed crop fields at 14, 21, 28 and 35 days after flower opening for each variety. Fresh pods were dried and seeds were extracted and dried to about 12% moisture content. Thereafter, seed quality evaluations were conducted in both laboratory and field. For seed quality assessments in the laboratory, seeds extracted at the various harvest dates in both seasons were subjected to standard germination, accelerated ageing and seedling evaluations. Field evaluations were conducted using 4- row plots laid out in a randomized complete block design (RCBD) replicated four times. Data were collected on emergence percentage (EPCT), emergence index (EI), growth rate (GR), relative growth rate (RGR), days to first flowering (DFI), days to 50% flowering (DF50) and seed yield (YD). All data collected were subjected to Analysis of variance to test the effect of season of production and harvest date on cowpea seed quality. Means were separated using Duncan’s Multiple Range Test. Seeds produced in late season had higher quality than those produced in early season. Seeds produced in early season had higher moisture content but lower hundred seed weight, and germination percentage. Harvest date influenced seed moisture content and hundred seed weight, germination, accelerated ageing germination and emergence percentages. Seeds harvested at 21 days after flower opening had the highest standard and accelerated aging germination percentages at moisture content of 45.71%. Therefore, cowpea seeds attained physiological maturity (PM) at 21 DAF. Thereafter, a week delay in harvest results in at least 30% percent decrease in germination. So harvest date is the main determinant of cowpea seeds.

Season of Production, Harvest Dates, Physiological Maturity, Hundred Seed Weight

[01] Akande, S. R., Olakojo, S. A., Ajayi, S. A., Owolade, O. F., Adetumbi, J. A., Adeniyan, O. N. and Ogunbodede, B. A. (2011). Planting date affects cowpea seed yield and quality at southern Guinea, savanna, Nigeria. Seed Technology. Pp 979-988. [02] Ali, I. M., Nulit, R., Ibrahim M. H. and Uddin, M. K. 2018. Effect of delay harvest on seed quality and germination of three varieties of soybean (glycine max) seedsPlant Archives18 (2): 1961-1966. Asio, M. T., Osiro, D. S. O. and Adipala, E. (2005). Multilocation evaluation of selected local and improved cowpea lines in Uganda. African Crop Science. 13: 239–247. [03] Asio, M. T., Osiro, D. S. O. and Adipala, E. Multiloactional evaluation of selected local and improved cowpea lines in Uganda. African Crop Science, 13: 239-247. [04] Ávila; M. R., Braccini, A. L., de Sá Motta. I., Scapim, C. A., and Braccini, M. C. L. 2003. Sowing seasons and quality of soybean seeds. Science Agriculture. (Piracicaba, Braz.) vol.60 no.2 Piracicaba. [05] Bailly, C. C., Audigier, F., Ladonne, M. H., Coste, F. C. and Come, D. (2001). Changes in oligosaccharides content and antioxidant enzyme activities in developing bean seeds as related to acquisition of drying tolerance and seed quality. J. Exp., Bot., 52: 701-8. [06] Bolina, C. C. (2012). Physiological maturation of the seed and determination of the appropriate harvest time of the bean (Phaseolus vulgaris L.). Scientific Journal Linkania Master, 2 (3), http://linkania.org/master/article/view/78/50 [07] Bornhofen, E., Benin, G., Galvan, D. and Flores, M. F. 2015. Sowing seasons and qualitative performance of soybean seeds. Pesquisa Agropecuaria Tropical. 45 (1): 46-55. [08] Botelho, F. J. E.; Guimarães, R. M., Oliveira, J. A.; Evangelista, J. R. E.; Eloi, T. A.; Baliza, D. P. (2010). Physiological performance of bean seeds harvested in different periods of development. Science and Agrotechnology, 34 (4): p.900-907. [09] Demir, I., Ashirov, A. M. and Mavi, K. (2008). Effect of Seed Production Environment and Time of Harvest on Tomato (Lycopersicon esculentum) Seedling Growth. Research Journal of Seed Science 1: 1-10. [10] Dandagi, M. R., Lakkundi, B. S., Patted, V. S., Merwade, M. N. and Tattimani, M. H. (2011). Evaluation of genotypes for seed qualitative parameters in Kharif and summer grown soybean [Glycine max (L.) Merril]. Advance Research Journal of Crop Improvement. 2 (1): 58-69. [11] Deshpande, V. K., Kulkarni G. N. and Kurdikeri, M. B. (1991). Storability of maize as influenced by time of harvesting. Curr. Res. 20: 205-207. [12] Elias, S. G. and Copeland, L. O. (2001). Physiological and Harvest Maturity of Canola in Relation to Seed Quality. Agronomy Journal 93: 1054 – 1058. [13] Eskandari, H. (2012). Seed quality changes in cowpea (Vigna sinensis) during seed development and maturation. Seed Science and Technology, v.40, n.1, Pp.108-112. [14] Gnyandev, B., Kurdikeri, M. B. and Salimat, P. M. 2019. Influence of harvesting stages on seed quality in chickpea varieties. Journal of Entomology and zoology Studies. 7(2): 314-317. [15] ISTA (2020). International Rules for Seed Testing. The Germination tests. Volume 2020(1):1-14 https://doi.org/10.15258/istarules.2020.05 [16] Kaya, Y., Demerci, M. and Evci, G. (2004). Sunflower (Helianthus annuus L.) breeding in Turkey for broomrape (Orobanche cernua Loeffl.) and herbicide resistance. Helia 27 (40): 199-210. [17] Krishnakumary, K. (2012) Pattern of fruit and seed development in vegetable cowpea varieties. Legume Research: An International Journal. 35: 53-55. [18] Leprince, O., pellizzaro, A. berriri, s., and Buitink, J. 2017. Late seed maturation: drying without dying. Journal of Experimental Botany, 68 (4), 827-841. [19] Loukou, A. L., Koffi, K. K., and Zoro, Bi Irie A. 2019. Effect of harvest time on germination power, seedlings vigour andyield of the oleaginous gourd Lagenaria siceraria seed in the rain forest of Côte d’Ivoire. Advances in Agricultural Science Volume 7 (01), 51-59. [20] Luis F. H., Adelina O. L., Lilia, I. L. and Liliana, B. I. (2008). Physiological maturity in sunflower. Correspondence between the quantitative and the visual definition. Proceeding of 17thInternational Sunflower Conference Córdoba, Spain. pp. 337-340. [21] Nautiyal, P. C.; Misra, J. B. and Zala, P. V. (2010). Influence of seed maturity stage on germinability and seedling vigour in groundnut. Journal of SAT Agricultural Research 8 Pp. 1-10. [22] Nogueira, N. W., Rômulo, M. O. de Freitas, Salvador, B. T., Caio, C. P. L. (2014) Physiological maturation of cowpea seeds. Journal of Seed Science, 36(3), 312-317. https://doi.org/10.1590/2317-1545v36n31007 [23] Ofori, K. and Klogo, P. Y. (2005). Optimum time for harvesting yardlong bean (Vigna sesquipedalis). International Journal of Agriculture and Biology 6: 324-327. [24] Singh, A. R. and Lachanna, A. (1995). Effect of dates of harvesting, drying and storage on seed quality of sorghum parental lines. Seed Science Research 13: 180-185. [25] Thant, P. S., A. B. Puteh, U. R. Sinniah and M. F. Ismail (2017). Physiological and chromosomal changes of delayed harvest soybean (Glycine max L. Merr.) seeds. Seed Science and Technology, 45 (2): 340-353.