GENETIC DIVERSITY OF Digitaria horizontalis Willd. IN BUILT ENVIRONMENTS IN BENIN CITY, NIGERIA

Abstract

The influence of humans on biodiversity at the genetic, species, community, and ecosystem levels is enormous. This is even more impactful on plant populations, which, being immobile, are at the mercy of their immediate environment. Digitaria horizontalis is a very common grass species in Benin City. Its ruderal nature accounts mostly for its widespread. The current study investigated the existence of possible genetic diversity of the grass in built environment in Benin City. Plant samples were randomly collected from 21 built environment locations within 6 Local Government Council Areas that make up Benin City. Test plants were allowed to acclimatize in experimental bowls and then allowed to grow for 4 weeks after which morphological characteristics were determined. Genetic diversity was determined by Random Amplification of Polymorphic DNA. Significant differences in plant height (33.0 – 59.0 cm) occurred when plants were compared based on location of collection. Changes in patterns of the association with weeds within the vicinity of the test plant was observed. The most prevalent plant species associated with the test plant was Pennisetum purpureum with a 12.18% prevalence. RAPD analysis using primer OPA 04 revealed a locus (about 600bp) that was absent in one or more of the locations with minimum disturbance. This 600pb fragment was however observed in most samples from highly built up and trampled environments. Primer OPA 03 showed monomorphic bands in 2 test samples with a band size of 400bp. It is therefore reported that there is an existence of the genetic diversity in a landscape of grass species (Digitaria horizontalis) found in different built environment in Benin City, Edo State, Nigeria.