Abstract
Abstract: The objective of this work was to evaluate the divergence among genotypes of Desmanthus sp. regarding morphological, productive, and qualitative characteristics, as well as to estimate the number of observations necessary to predict the real value of these characteristics. The experiment was conducted in the semiarid of the state of Pernambuco, Brazil, using 26 genotypes of Desmanthus sp. from different locations in the region. Seven evaluations were carried out from July 2013 to July 2014. Tocher’s grouping method and standardized average Euclidean distance were used. The coefficients of repeatability (r) and determination (R2) were estimated using two models of the analysis of variance, principal components based on the correlation or covariance matrix, and structural analysis based on the correlation matrix. The variables with the greatest weights were stem diameter, leaf area index, and forage yield, with frequencies of 22.05, 17.57, and 14.58%, respectively. Morphological, productive, and qualitative variability was observed among the genotypes of Desmanthus sp. All characteristics presented r and R2 of high magnitude in the methods of analysis. Up to four evaluation cycles are required to predict (R2=95%) the real value of stem diameter, peduncle length, plant height, leaf length and width, number of leaves, and pod length.
Highlights
The Desmanthus genus is composed of 24 legume species naturally distributed in tropical and subtropical regions of the Americas (Muir et al, 2014)
The objective of this work was to evaluate the divergence among genotypes of Desmanthus sp. regarding morphological, productive, and qualitative characteristics, as well as to estimate the number of observations necessary to predict the real value of these characteristics
Repeatability coefficients were estimated based on five different methods described by Cruz et al (2014): two models of the analysis of variance (ANOVA 1 and 2), principal component analysis (PCA) based on the correlation (PCACOR) or covariance (PCACOV) matrix, and structural analysis based on the correlation matrix (SACOR)
Summary
The Desmanthus genus is composed of 24 legume species naturally distributed in tropical and subtropical regions of the Americas (Muir et al, 2014). It should be noted that genotypes of Desmanthus may show variability regarding morphological, productive, and qualitative characteristics, as is the case of those collected in the Brazilian semiarid region (Calado et al, 2016; Diniz, 2016). It is essential to expand knowledge on the variability of naturally occurring genotypes as the basis for future forage breeding programs, especially with native plants that still require additional information to improve the efficiency of their use. This is important since the genetic breeding of tropical forages is still a very recent activity compared with that of temperate forages (Jank et al, 2014). The gradual degradation process of Brazilian native biomes highlights the need to obtain more information on available plant genetic resources, an aspect of great interest for germplasm collection and assessment activities
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