Mitotic Activity in Cowpea ( Vigna unguiculata (L.) Land Race “Olaudi” Walp) in Nigeria

Abstract

Cowpea, Vigna unguiculata is a major staple for millions of households in the tropics. A cowpea land race, “Olaudi” collected from South-Eastern Nigeria was investigated for mitotic indices during cell division. Root tips were pre-treated with 8-hydroxyquinoline for three hours, fixed in Carnoy’s solution (alcohol-acetic acid solution 3:1 v/v) for 24 hours, hydrolysed in 1 NHCl and squashed in aceto-orcein. Various stages of mitosis were recorded to determine mitotic activity in dividing cells. Results obtained showed that active cell division occurred between 7.00 AM and 2.00 PM but peaks between 11.00 AM and 1.00 PM. Although cells at the prophase stage were in a continuum, they became observable between 8.00 AM and 3.00 PM, but greater proportion of cells was observed at 12.00 PM. Cells at metaphase were generally observed during a six hours period between 8.00 AM and 1.00 PM, but the peak period was 11.00 AM. Mitotic activity at anaphase commenced around 10.00 AM late morning but plateaus for two hours early afternoon between 12.00 PM and 2.00 PM. Telophase activity was mostly observed at 11.00 AM within a five hour period between 9.00 AM and 2.00 PM. Mitotic index peaked at 1.00 PM with 65.3% of cells in active cell division, with a concomitant high mean germination percentage (63.5%). This study provides useful basic information to guide further cytogenetics research in the genetic improvement of this local cowpea landrace.