Genotype by environment interaction and teak (Tectona grandis L.) selection in Costa Rica

Abstract

A teak progeny trial was established with four replicates at different sites along the northern Pacific region of Costa Rica. The trials followed a randomized block design, with 28 open pollinated families and 36 seedlings per family per site. Data from 7 years-old trees was analyzed both for each test location separately and for all locations combined. High individual heritability was found for diameter, which translates to higher breeding potential. The all locations combined analysis showed high genetic variation, with individual heritabilities reaching up to 22 %. Genotype by Environment (GxE) interactions explained only 2.5 % of total phenotypic variation. The genetic correlation (rg) among all four sites was 0.69. Hence, it is concluded that GxE interactions are not problematic for breeding purposes since they are not complex in nature. This teak breeding population showed strong genetic stability and performed well in most environments in the study area. The Hojancha location showed high genetic correlation with all other sites; therefore, it should be chosen for future testing and selection of elite genotypes. Selection of the 20 best individuals, allowing for up to two individuals per family, would result in a 1.78 cm (11 %) gain in diameter. Furthermore, based on this selection the inbreeding coefficient (F) in the offspring would only reach 2.9 %, while the expected effective population size (Ne) would be16.97 individuals. This selection scheme could reduce rotation age by almost two years, since the diameter goal of 40 cm would be reached earlier than the usual 20 years cycle. The results suggest that the progeny trial can be maintained as a single breeding population, suitable for planting in any site along the Northern Pacific region of Costa Rica.

Productivity, adaptability, and stability in Guazuma crinita progeny tests across three environments in the Aguaytia River Basin, Ucayali, Perú

“…In this context, it is necessary to select productive genotypes that can be successfully used in conservation and improvement programs for reforestation. This requires an understanding of the interaction between genotypes and environments (GxE) in order to minimize or leverage the effects and increase efficiency in the selection of genotypes (Pupin et al, 2018;Murillo et al, 2019).…”

Genetic tolerance to Ceratocystis wilt in melina (Gmelina arborea Roxb.)

“…The clonal test was established following a randomized complete block experimental design developed by GENFORES (Murillo et al, 2019). Within the six blocks, 34 elite genotypes were tested, each represented by two pairs of ramets randomly distributed within each block, with the restriction of not planting two pairs of the same clone together.…”

“…To proceed with selection of genotypes scenarios, the genetic ranking of Pathogenicity Index and DBH growth were graphically compared, as suggested by Murillo et al (2019). Each of the two ranking was divided into three thirds: high, medium and low performance.…”

“…Subdivisions were obtained by (the difference between highest-lowest value)/3, as described by Resende et al (2018). Finally, a deviance analysis was performed, as suggested by Murillo et al (2019), to determine the existence of significant differences among genotypes.…”

Selección clonal de Tectona grandis L. f. para el Pacífico seco de Costa Rica

“…De esta comparación se obtuvo una ganancia genética de un 11% en volumen comercial, que es significativa y de alto impacto. Con un aumento en crecimiento de esta magnitud, una plantación clonal de teca lograría reducir en 1 a 2 años el turno de rotación en el Pacífico seco del país (Murillo et al, 2019).…”