Phenology and morphological diversity of sweet potato (Ipomoea batatas) landraces of the Vale do Ribeira

Abstract

The phenotypic diversity of sweet potato (Ipomoea batatas) landraces was assessed using morphological traits, verifying how this diversity is distributed among the households and settlements of the Vale do Ribeira, Brazil. A total of 74 accessions, involving 53 landraces, collected from 30 households distributed among 18 settlements that practice traditional agriculture in the municipalities of Iguape, Ilha Comprida, and Cananeia, as well as four commercial varieties acquired in markets of Iguape and Piracicaba, were evaluated under an ex situ experimental condition in Piracicaba, SP, Brazil. Nine phenological and floral descriptors, nine morphological vegetative aerial descriptors and five storage root traits were recorded. The 14 aerial vegetative and root descriptors were evaluated as binary data, totaling 74 attributes. Cluster analyses were made using the Jaccard similarity index and the UPGMA (unweighted pair group method with arithmetic mean) agglomerative method. Binary data was also submitted to a variance analysis (AMOVA). No defined groups were observed, indicating that the diversity of the landraces is not structured in space, but considerable morphological variation was found in this area (Jaccard similarity index varying from 0.12 to 1.0). Most of the variability occurred within households (64.4%), followed by the distribution among households within settlements (27.1%) and among settlements (8.4%). Thus, the traditional agriculturists of Vale do Ribeira maintain a high morphological diversity for sweet potato within their households, which can be assumed to be produced by the outcrossing mating system of this species and somatic mutation events, as well as the exchange system at local and regional levels.

Collection and morphological characterization of sweet potato landraces in north of Rio de Janeiro state

“…However Veasey et al (2007) observed a predominance of very superficial lobe (40%) and a much lower frequency of moderate lobe than in the present study, of around 15.0%.…”

“…Daros et al (2002) reported the pink color as predominant (50%). However, Chávez et al (2006) and Veasey et al (2007) reported predominance of cream coloring while Ritschel & Huamán classified the skin color as white for 41.2% of the accessions, and the second greatest frequency was for the pink coloring, represented by 28.6% of the accessions studied.…”

“…These variables were also mainly responsible for the genetic divergence in the results obtained by Oliveira et al (2000) and Cavalcante et al (2009). On the other hand, Veasey et al (2007) that most contributed to diversity. In the present study the characteristics that contributed least to divergence were pulp coloring and secondary root pulp coloring, 93.5% of the accessions had cream-colored pulp and 76.1% did not have a secondary pulp color.…”

“…Augustin et al (2000) obtained 90% frequency for mature leaf green coloring. Veasey et al (2007) similarly classified for mature leaf coloring 60% of the genotypes with green coloring and 40% with purple nervures on the lower surface. For immature leaf coloring, 50% of the leaves were classified as green with purple edges 20%, as green leaves, other colorings were also obtained but at lower frequencies.…”

“…One of the main characteristics of the sweet potato is its high phenotypic and genotypic variability (Vilas Boas et al, 1999;Veasey et al, 2007) that confers adaptability to different edaphoclimatic conditions. The sweet potato has been cropped empirically by most farmers (Zero & Lima, 2005) and much of what is known about the sweet potato comes from popular knowledge.…”