The Approach in Selecting the Best Genetic Resistance against Invasive Aphid for Indigenous Tropical Pinus merkusii Jungh. et de Vriese in Indonesia

Pinus merkusii, a natural tropical pine species of Indonesia, is cultivated as the second most important artificial forest for the industry in Java, after teak, to produce oleoresin. Its genetic improvement began in 1977 because of its critical role in raising community incomes. Meanwhile, the effort for genetic improvement in aphid (Pineus boerneri) resistance has just recently started since its spread was only found broadly in Java by 2004. The second-generation progeny trial for this purpose was established in 2010, with materials from the best growing 34 families of the first generation. This study aimed to obtain the best pine genotypes through screening the existing natural variations found on important characters. The reported incidence of the trigger was when the experiment was attacked significantly at 30.7% after four years, while some 67 individuals were unexpectedly still performing well after six years. The results show that blocks affect differences for all traits of diameter, aphid resistance, and oleoresin productions, and all families differ except for the west-side yield of oleoresin production. Furthermore, heritability values at individual and family levels were moderate for the diameter (h2i = 0.16; h2f = 0.53) and eastern oleoresin (h2i = 0.14; h2f = 0.42). The gain is 4.3% when 30% of families with the best diameters are retained, while the genetic gain reaches 11% for oleoresin production. As one of the important traits in the breeding program, aphid resistance has a weakly inherited trait (h2i =0.07; h2f =0.29). Interestingly, this trait shows positive moderate genetic correlations with the two essential economic values of diameter (rg = 0.66) and oleoresin production (rg = 0.40). Therefore, the selection of the diameter and oleoresin production will not substantially affect the resistance.