Phenological diversity of flowering and fruiting in cassava germplasm

Abstract

Genetic and environmental factors can influence the flowering and fruit setting performance of cassava varieties. The objective of this work was to assess the genetic variability of cassava germplasm for flowering and fruiting traits, as well as to cluster the genotypes based on based on its flowering performance. A total of 1032 accessions were evaluated monthly from 3 to 12 months after planting – MAP for flower and fruit production using a grade scale ranging from 0 absence or poor flowering to 3 full flowering, and the accumulated degree-days ADD was recorded for each period. The following traits were analyzed: a the mean flowering score MFS from 3 to 12 MAP and b a weighted average of the flowering scores that emphasizes early flowering WAS. The cassava accessions were clustered based on principal component analysis PCA. Seven clusters were identified via PCA, with very contrasting traits including a early flowering 8.5 % of the accessions, Group 4); b) consistent flowering after 2036 ADD (0.6 % of the accessions, Group 2); and c) accessions that do not flower (54 % of the accessions, Group 7). For most of the cassava germplasm, flowering occurred during the longest photoperiod (5–6 MAP). This study demonstrated that accessions belonging to Group 2 are very interesting for breeding programs and genomic studies due to their high flowering throughout the year. This is the first report of phenological diversity of flowering and fruiting performance in cassava germplasm.