Implications of the age of Hevea progenies in the precocious yield

Abstract

The objective of the present study was to promote a better understanding of the rubber yield of young progenies of Hevea brasiliensis evaluating the stability and the repeatability of early rubber yield test employed in a genetic breeding programme. The genetic material consisted of 30 open pollination progenies evaluated in the Colina county, Sao Paulo state, Brazil, in a randomised block design. Rubber yield was evaluated by the Hamaker Morris-Mann early rubber yield test in 5-year-old plants and the modified Hamaker Morris-Mann test in 3- and 4-year-old plants. The mixed linear model procedure Reml/Blup (Restricted Maximum Likelihood/Best Linear Unbiased Prediction) was used in the statistical analyses. The progeny effect was significant and indicated favourable conditions for selection. The rubber yield trait was highly influenced by the environmental conditions in the different measurements. The predicted genetic gains indicated favourable conditions for selection. The repeatability coefficient ( $$\hat{p}$$ = 0.42) showed a moderate capacity of the genotypes to repeat the expression of the trait in the same manner from one measurement to another. Selection made on the criterion of temporal stability for early rubber yield coincided better with progenies selection in the fifth year than with selection in the third year. The predicted genetic gains indicated favourable condition for progenies selection using early yield tests at different ages. Early selection of high yield progenies in the third year, selects partially promising progenies. Therefore, when early selection is made in the third year, selection in the following years is recommended.