Conservation of the germination capacity of pollen grains in three varieties of maize (Zea mays L.)

Abstract

Maize pollen longevity is short under natural conditions, and the seed yield is hampered by poor synchronisation between pollen shed and ovule maturity. Hybridization during stress conditions could be improved if pollen is collected and stored for use at appropriate times. This study was initiated to determine the optimum conditions for in vitro maize pollen germination. The method of pollen conservation and its viability over time was also part of the study. The pollen from three Zea mays cultivars (Exp1 24 and 5057, two inbred lines, and Tuxpeño sequía which is an open pollinated cultivar) were used in this study. The conservation was evaluated using three different methods: room temperature, the refrigerator (+10°C), and deep‐freezing at −20°C. Two base culture media (Brewbaker & Kwack, Heslop‐Harrison) were used for in vitro pollen germination. The effects of saccharose concentrations, incubation and desiccation times, were also evaluated. Results from this study showed that, Heslop‐Harrison medium was better than Brewbaker and Kwack or and with pollen germination. Pollen stored in a refrigerator (+10°C) varying desiccation times, yielded the following findings: for a short conservation time (10 days maximum), there is no need for a prior desiccation. For a medium conservation time (between 16 days and 20 days), five to six hours desiccation time are needed to obtain maximum germination for inbred line Exp1 24 and for the composite variety Tuxpeño sequía respectively. It was also determined that, at room temperature, maize pollen could germination is longer than 24 hours. The use of deep‐freezer at −20°C did not yield any consistent result. In vivo germination test in a maize field will be necessary to confirm the above in vitro germination.