Florescimento e viabilidade de pólen de açaizeiros do Pará na Amazônia Ocidental

Abstract

Açaí (Euterpe oleracea Mart.), Arecaceae family, is a perennial palm appreciated by the Amazonian population. Its main importance is the use of the fruit that is processed and consumed in the drink called açaí. The product is expanding in the national market and among the native fruit trees is considered to have great potential to reach international markets. Much of the production of açaí still comes from extractivism which does not offer quality products. Obtaining basic information is still necessary for the domestication and genetic improvement of the species in order to obtain cultivars for planting. The objective of this research was to study flowering and to define an efficient method of analyzing the viability of Euterpe oleracea pollen. The study of reproductive biology and pollen viability was carried out on açaí plants from the experimental area of the headquarters (Manaus, Amazonas) and the Experimental Station of Rio Urubú (Rio Preto da Eva, Amazonas) of Embrapa Amazônia Occidental. Observations of inflorescence emission and fruiting in the field and analysis of the viability of pollen and germination were carried out in the laboratory. For descriptions for fruiting, flowering and pollen analysis were conducted using digital machines and stereoscopic microscopes. For the evaluation of the viability of pollen, three colorimetric methods were tested; Tetrazolium (0.1%), Cotton Blue (0.05%) and Triphan Blue (0.2%); three dye solutions with 3 replicates of three genotypes. The percentage of viable pollen was obtained by calculating the number of viable grains divided by the number of grains counted and then multiplied by 100, counting 200 grains / blade. The results were compiled through analysis of variance and later applying the Tukey Range test. Pollen viability of an inflorescence was also monitored over ten consecutive days. Additionally, the viability of fresh pollen after storage for one month was also studied. Pollen germination was studied through in vitro culture as well. The analyses were performed in the Genes software. The results showed that for E. oleracea, in Western Amazônia, flowering events were more frequent during the rainy season, while fruiting was prevalent in less rainy periods. All dyes allowed for the differentiation between the viable pollen grains of those not viable in E. oleracea. However, Cotton blue (0.05%) and Tetrazolium (0.1%) presented higher contrasts at the time of counting the number of viable pollen when compared to the Blue Triphan (0.2%), Cotton blue (0.05%) and Tetrazolium (0.1%). Furthermore, they were able to distinguish viable pollens from those not viable in E. oleracea because they presented a percentage viability rate above 70%. This percentage is considered satisfactory for improvement. Among the evaluated dyes, Cotton blue (0.05%) is recommended for pollen viability monitoring in E. oleracea. This is due to the association of the pollen viability percentage analysis results with higher qualities in the pollen contrast discrimination power making them feasible and unviable. The conservation and maintenance of pollen viability of E. oleracea genotypes can be performed in vitro at -20 ° C for at least 30 days.