Análisis in vitro de la calidad del polen de diez ecotipos de chirimoyo (annona cherimola mill).

Abstract

Cherimoya (Annona cherimola Mill) has low production, originated by several factors, among them, low index of pollinating agents, frequent alternation of the floral cycles, the flowers present a closed structure, little noticeable to insects and a marked type of protogynous dichogamy. Exporting countries of this fruit, such as Spain, Chile, Peru and others, see the use of manual pollination as an alternative production, although in many cases this technique shows inefficient results in fruit set and fruit development, being necessary to investigate the possible existence of other factors that limit production, including the source and quality of the pollen used. In this study, the pollen quality of ten ecotypes of cherimoya existing in the ex-situ collection of the Austro Experimental Station of the National Autonomous Institute of Agricultural Research (INIAP), located in the canton Gualaceo, was determined in vitro. The pollen was carried to the Phytopathology Laboratory of the Agronomic Engineering Career of the Catholic University of Cuenca for evaluation. The culture medium used for pollen sowing contained 10% sucrose, 1% agar, 50 ppm boric acid and 625 mg / l calcium nitrate. The percentage of germination, length of the pollen tube at 2, 4, 8 and 24 hours in three phenological stages and the shape and size of the pollen grain were evaluated. The completely random design was used in factorial arrangement 10 ecotypes x 4 times x 3 phenological stages with four repetitions. For the statistical analysis, the variance analysis and Tukey's test 5% to mean separation were applied using the InfoStat software. In conclusion, the highest percentage of germination presented the Fino de Jete ecotype at 24 h, and the highest pollen tube length reached the Austro ecotype in the same period of time; in addition, the pollen must be collected in male phenological stage due to the greater pollen tube length.

Key words: Annona cherimola, phenological stages, pollen germination, pollen growth tube.