Morphological Comparison of Progeny Derived from 4x‐2x and 4x‐4x Hybridizations of Lotus glaber Mill. and L. corniculatus L

Abstract

Unreduced gametes (2n gametes) from Lotus glaber Mill. (2n = 2x = 12) may aid intercrossing with L. corniculatus L. (2n = 4x = 24) to produce progeny with a greater heterotic advantage than progeny derived from colchicine‐induced {7‐acetamido‐6,7‐dihydro‐1,2,3,10‐tetramethoxybenzo[a]heptalen‐9(5H)‐one} tetraploid (4x) L. glaber The objective of this research was to compare progeny produced from 4x with 2x (4x‐2x) and 4x with 4x (4x‐4x) crosses and determine if 2n gametes had a heterotic advantage over normal gametes derived from colchicine‐induced tetraploids. Vegetative cuttings of the 2n‐gamete‐producing L. glaber genotype 204882‐1 (2x 204882‐1) were treated with colchicine and successfully yielded an autotetraploid (2n = 4x = 24) of 204882‐1 (4x 204882‐1). Three randomly chosen genotypes from the L. corniculatus germplasm MU‐81 were used as maternal parents in crosses to 2x 204882‐1 and 4x 204882‐1. Progeny produced from 4x‐2x crosses were intermediate to or larger than their parents in their leaf and flower morphology. Progeny from 4x‐4x crosses were intermediate to or smaller than their parents in leaf and flower size. Size of leaves and flowers of progeny from 4x‐2x crosses were similar to or larger than 4x‐4x progeny. Morphological comparisons demonstrated that heterotic expression of progeny from 4x‐2x crosses was greater than progeny from 4x‐4x crosses. The results indicate that the generation of interspecific L. corniculatus × L. glaber hybrids via 2n pollen to be effective, but a means of exploiting any heterotic advantage in these cross‐pollinated species needs to be identified.