Seleção de progênies, repetibilidade, diversidade genética e viabilidade de pólen em Sacha-inchi (Plukenetia volubilis L.)

Abstract

Sacha-inchi (Plukenetia volubilis L., Euphorbiaceae) was introduced in Manaus, Brazil, with the intention of developing a market niche for an oil with very nutritious food characteristics. The introduction of a crop requires assessment of the species' adaptation to its new environment and planning for future development, including genetic improvement. The objective of this work was to introduce accessions of P. volubilis in Manaus, from Peru, to expand the existing germplasm aiming at genetic improvement. Progeny selection, repeatability analysis, genetic diversity and pollen viability in sacha-inchi were performed. Open pollinated progenies of sacha-inchi showed phenotypic genetic variability for fruit and yield characteristics. High genetic correlations between the number of fruits, fruit yield and seed weight per plant (r > 0.96) and high heritability values in the three mentioned traits (h2> 0.81) were observed. The characters number of fruits and fruit weight showed indirect genetic gains on seed weight yield (GS% = 23%). However, the fruit weight character is recommended to estimate seed production. Direct selection on average fruit weight showed a negative effect on genetic gains of seed production per plant (GS% = -15%), number (GS = -19%) and fruit production per plant (GS% = -12 %). The selection of large fruits, as has been done by producers, does not reflect good seed yields, which is also observed in the lack of direct and indirect effects of the average fruit weight on the weight of seeds per plant. Low direct selection intensity (42%) on the fruit yield per plant allowed significant indirect gains on the seed yield per plant (23%) and showed potential to maintain genetic variability. Accessions Cuzco, Dos de Mayo, Shanao, Aucaloma and AM-07 were selected for their high yields in fruits and seeds. For good accuracy of the repeatability parameter, in the Principal Components (CP) method, the use of the covariance matrix showed a better repeatability coefficient than the use of the correlation matrix for the characters number of fruits, fruit yield and yield of seeds per plant both for individual selection and for the selection of progenies. As the evaluation of the number of fruits is easier than the production of fruits and seeds, it is recommended to evaluate by the number of fruits. Thus, for the selection of progenies and individual plants, three and seven months of consecutive harvest are indicated, respectively. The use of Principal Components coordinates proved to be adequate to explore the phenotypic genetic diversity in sacha-inchi. According to the analysis of the phenotypic genetic diversity, the following hybridizations are recommended: Cuzco x Dos de Mayo, Cuzco x Aucaloma, Shanao x Cuzco, Shanao x Aucaloma, Shanao x Dos de Mayo, Shanao x Am07, Dos de Mayo x Aucaloma.germination In vitro, liquid culture medium with 10% sucrose and 0.03% Ca(NO3)2.4H2O is the best method to estimate the viability of sacha-inchi pollen.