ISSN: 0974 – 3987 IJBST (2020), 13(2): 18-33 DOI: http://doi.org/10.5281/zenodo.4019163 International Journal of BioSciences and Technology (2020), Volume 13, Issue 2, Page(s): 18 – 33 18 GT biplot analysis of shoot traits indicating drought tolerance in cowpea [Vigna unguiculata (L.) Walp] accessions at vegetative stage Abiola T. Ajayi 1 , Alaba E. Gbadamosi 2 , Victor O. Olumekun 3 , Precious O. Nwosu 4 1-4 Department of Plant Science and Biotechnology, Adekunle Ajasin University, Akungba-Akoko, Nigeria 4 Registry Department, Kings Polytechnic, Ubiaja, Nigeria toyin.ajayi@aaua.edu.ng, alaba.gbadamosi@aaua.edu.ng, victor.olumekun@aaua.edu.ng, nwosup1991@gmail.com ABSTRACT The present study was done to analyse trait association and genetic variation in cowpea under drought stress at vegetative stage by GT biplot analysis. Ten accessions of cowpea were grown in pots filled with 7 kg of top soil in 3 replicates in completely randomised design (CRD). Each pot was applied 500 ml of water every other day for 5 weeks; then drought was imposed for 3 weeks by withholding watering. Data were collected on wilting parameters, stomata conductance and morphological characters. Plants were re-irrigated after 3 weeks of stress for another 2 weeks; collection of data on recovery parameters and number of pods were done. Data were subjected to analysis of variance and GT biplot analysis. Biplot revealed that wilting parameters excluding leaf wilting index, recovery traits and number of pods were very important traits to be considered for breeding for drought tolerance in cowpea. The highly susceptible accessions were AC08, AC10 and AC03, while the most tolerant accessions were AC06 and AC07. Key words: GT biplot, drought tolerance, cowpea, wilting index, recovery INTRODUCTION Cowpea plays a significant role in the protein requirements of humans and animals making it one of the most important legume crop in the sub-Saharan Africa (SSA) and most especially in Nigeria. Small scale farmers depend on the crop for its nutrition potential, enhancement of soil fertility and income drive [1], [2], [3]. Cowpea grains are rich in calcium (826 mg/kg), magnesium (1915 mg/kg), phosphorus (5055 mg/kg), potassium (14,890 mg/kg), protein (25% content), iron (53.20 mg/kg) and zinc (38.10 mg/kg). It has the capacity to fix about 70 to 350 kg of nitrogen per hectare of soil making its projected potential impact between the periods of 2011 to 2020 lies around 77,320 tons [4]. Africa accounts for 83% of the worldwide cowpea production (6.5 MT/annum), more than 80% of Africa’s production come from West Africa with 55% accounted to Nigeria being the world’s largest producer at 45% estimated global production [1]. Despite the efforts of many workers at improving cowpea productivity against any known constraint, its productivity is hampered significantly by drought stress especially if exposed to drought at seedling stage, vegetative stage or terminal drought [3], [5]. Drought is one of the misfortunes associated with climate change as evident on plant growth and development, thereby propelling input of researchers in the direction of developing genotypes with