Morpho-biometric characterisation of Brachiaria spp germplasm in the area of mount Cameroon

Abstract

Brachiaria grass has a major potential to relieve the polygastric livestock sector and support its growth in pastoral and extensive mixed systems where ruminants suffer permanent or seasonal nutritional stress from inadequate feed supply as an endemic problem. Morphological description of Brachiaria spp germplasm is helpful for the identification and delimitation of taxa that could lead to accession collections and selection of varieties with high agronomy value. The identification of potential accessions of Brachiaria in the mount Cameroon area was phenotypically based on twelve qualitative and eleven quantitative descriptors, data been collected using a structured questionnaire. The Brachiaria spp have light green coloured leaves (70.9%) which are mostly pubescent (34.5%), intermediate (29.1%) or glabrous (25.5%). The internodes are mostly yellow green (25.5%), the stigma is mostly white (40.0%) while the own panicle is mostly absent. The panicles are mostly open (61.8%) while the grains are mostly round shaped (74.5%). The glumella pubescence is mostly absent while the lemma and palea mostly have a straw colour and the apiculus and/or awn colour are mostly absent (74.5%). There is huge variability for the quantitative traits whatever the locality is. The traits varying most are the number of panicle per plant (146.86%), the grain weight (141.17%) and the number of spikelets per plant (135.10%). The correlation between measurements vary from weak to moderate, the highest positive significant (p<0.01) correlation coefficient (0.637**) was observed between the flag leaf length and the panicle length, while the significant native correlation (-0.283*) was found between the panicle fertility and the flag leaf width. The cumulative variance of the first five principal components explains 73.958% the genetic variability observed within the studied population. The flag leaf length, flag leaf width and culm length are components contributing most to that variability, with respectively 23.10%, 17.16% and 13.16%, giving a total cumulative genetic variability value of 53.43% of the whole Brachiaria spp population germplasm in the area of mount Cameroon. The hierarchical clustering revealed that there could exist four main clusters or accessions of Brachiaria spp germplasm in the area of mount Cameroon. Accession 4 is the most distant from the three others, while accessions 1 and 2 are the closest. The clustering into groups of accessions with similar morphological within the collection Brachiaria germplasm in this study will enable researchers interested in this grass to easily identify subsets of  accessions for further evaluation aimed at specific uses.  Morphological differences between these accessions and taxonomic differentiation to species level will need molecular characterization for confirmation.