Bayesian random regression for genetic evaluation of South American leaf blight in rubber trees

Abstract

RESUMO -O mal das folhas causado pelo fungoMicrocyclus ulei é a doença mais séria dos seringais da América Latina. Com o objetivo de identificar clones de seringueira mais resistentes em diferentes ambientes ao longo do tempo, compararam-se diferentes modelos de regressão aleatória (MRA) ajustados via abordagem Bayesiana. Oito clones foram testados em campos clonais no delineamento em blocos completos casualizados com quatro repetições, utilizando-se 80 árvores por parcela. As duas fileiras centrais foram avaliadas a cada dois meses em relação às variáveis severidade (SEV) e índice de estroma em folha adulta (EFA). Foram incluídas como covariáveis nos modelos a circunferência do tronco e as variáveis climáticas de cada campo clonal. Os MRA foram comparados por meio do critério DIC (Deviance Information Criterion). O modelo M2 (que assumiu os efeitos aleatórios quadrático para clone e linear para planta) foi o melhor (menor valor de DIC) para descrever SEV e EFA em todas as localidades consideradas. Tal modelo permitiu inferir que os clones FDR 5788, CDC312 e CDC56 apresentaram maior resistência, enquanto o clone FX 3864 foi o que apresentou a maior suscetibilidade, em todas as localidades consideradas. Palavras-chave: Hevea brasiliensis. Microcyclus ulei. Dados longitudinais. Inferência estatística. Simulação estocástica.ABSTRACT -This model enabled also to infer that the clones FDR 5788, CDC312 and CDC56 presented high resitance, while the colne FX 3864 was the most susceptible in all studied locals. South American leaf blight caused by the fungus Microcyclus ulei is the most serious disease of rubber plantations in Latin America. With the aim of identifying more resistant rubber-tree clones in various environments over time, different random regression models (MRA) adjusted via a Bayesian approach were compared. Eight clones were tested in clonal fields in a randomised complete block design with four replications, using 80 trees per lot. The two central rows were evaluated every two months for the variables severity (SEV) and stroma index of the adult leaf (EFA). Trunk circumference and the climatic variables of each clonal field were included in the models as covariates. The MRA were compared by the deviance information criterion (DIC). The M2 model (which assumed quadratic random effects for clones and linear effects for plants) was the best (lower values for DIC) in describing the SEV and EFA in all the locations being considered. Such a model suggests that the FDR 5788, CDC312 and CDC56 clones displayed greater resistance, while the FX 3864 clone displayed the highest susceptibility in all considered locations.

Multi-Environment and Multi-Year Bayesian Analysis Approach in Coffee canephora

“…Another advantage is that credibility intervals are often reported as smaller than confidence intervals if an appropriate prior has been used, as observed in guava, another perennial fruit tree [ 14 ]. Due to the likelihood function, if a non-informative prior is used, a Bayesian performance at least similar to the frequentist is expected [ 21 , 22 , 23 ].…”

Foliar and flowering phenology of three rubber (Hevea brasiliensis) clones in the eastern plains of Colombia

“…Phenological evaluation -In each marked tree of clones RRIM 600, FX 3864 and IAN 873, foliar density was evaluated with a scale from 0 to 10, where 10 corresponds to 100% of leaves in the crown and 0 to the absence of leaves (Cevallos et al 2012;Rivano et al 2016), the percentage of leaves in stages A, B, C and D (Lieberei 2007), indicating that the D1 stage corresponds to mature leaves of the previous year, and D2 and D3 as the leaves formed in the refoliation cycles of the following years (Rivano et al 2016). Moreover, the flowering density was measured on a scale from 0 to 10, where 0 corresponds to the absence of flowering and 10 to the presence of inflorescences in 100% of the branches of the last floor of the trees, and finally, the where % X corresponds to the percentage of the crown that shows a certain foliar or inflorescence state development, and n is the percentage of leaves or inflorescences observed in a certain stage of development.…”

“…In P. ulei non-escape zones, susceptible clones have low levels of retained leaves during the defoliation and refoliation period and the level of foliar damage is probably associated with the duration and intensity of each clone´s phenological cycle (Sterling et al 2019). This study evaluates the foliar and flowering phenology of P. ulei susceptible rubber clones like FX 3864 (Cevallos et al 2017), IAN 873 (Sterling et al 2019) and RRIM 600 (Rivano et al 2016) under non-escape conditions (Castañeda 1997) in Meta (Colombia).…”