Heritability for resistance to Puccinia psidii Winter rust in Eucalyptus grandis Hill ex Maiden in Southwestern Brazil

Abstract

The climates of the central and southern regions of Sao Paulo state in Brazil favor pathogens such as Puccinia psidii Winter, which causes a common and severe disease in Eucalyptus plantations under 2 years old. We studied genetic parameters including genotype by environment interaction (G × E) of resistance to P. psidii rust in Eucalyptus grandis at nine sites in Sao Paulo State. Open-pollinated progeny from ten ‘provenances’ were established in a randomized complete block design; at individual sites there were from 134 to 160 progenies, from four to eight blocks, and five to six trees per plot. Significant provenance and progeny(provenance) differences were detected, as was G × E involving progeny(provenance). However, the G × E involved little if any rank changes, indicating that selection can be done efficiently at a single site, if the disease level is sufficient. The estimated coefficient of genetic variation among the progeny within provenances $$ \left( {{{{\widehat{\mathrm{CV}}}}_{\mathrm{g}}}} \right) $$ was high and variable among the sites (ranging from 11 % to 36.7 %), demonstrating different expression of genetic variability among the sites. The estimated heritability at the individual-tree level $$ \left( {{{\widehat{h}}^2}} \right) $$ and within a plot $$ \left( {\widehat{h}_{\mathrm{w}}^2} \right) $$ ranged from low to intermediate (ranging from 0.04 to 0.46) and was high at the progeny-mean level $$ \left( {\widehat{h}_{\mathrm{f}}^2} \right) $$ (ranging from 0.30 to 0.86). Our study shows good prospects of controlling this disease by selection among and within progenies in a single site.