Selection for increasing 2n gamete production in red clover

Three selection cycles were performed in the red clover cultivars Quiñiqueli, Redland and Keenland to increase the 2n gamete production. Unreduced gamete production was estimated by the giant pollen grain (GP) production. Plants with more than 1% of GP were selected as progenitors from the original population; plants with at least 2% and 3% of GP, respectively, were selected and crossed for the second and third cycles. The GP production ranged from 1.4 to 7.5% in the first, 2.0 to 51.0% in the second, and 3.0 to 46.7% in the third cycle. Considering the three cultivars together, there was a significant increase in GP production from the first (4.0%) to the third (8.9%) cycles. ‘Redland’ presented higher GP percentages in each cycle and significant and steady GP production increases along the three cycles: 4.8, 13.4 and 19.7%, respectively, and should be included in further attempts to obtain sexual polyploids.