Hybridization of Desmodium species

Summary

Under different light regimes, Desmodium canum (Gmel.) Schin. & Thell. responded as a long-day plant, D. intortum (Mill.) Urb. and D. uncinatum (Jacq.) dc. as short-day plants, and D. sandwicense E. Mey. as photoperiod-insensitive. Tripping method with anther removal, washing of stigmas and pollen transfer was simple and less time-consuming, gave an equal number of hybrids but more selfed progenies than the tedious method of emasculating prior to anthesis. A high percentage of selfing indicated that the four species are self-compatable and that foreign pollen did not show advantage over that from the same plant. Silver marking of the leaflet midrib of D. sandwicense and D. uncinatum in crosses with D. intortum was a useful dominant marker, but did not appear in the cross D. canum × D. uncinatum. Brown flecking of D. intortum leaflet was a dominant characteristic and occurred on the progenies from crosses with D. sandwicense and D. uncinatum along with the silver marking. Stem growth habit, leaflet form, and pubescence were helpful but less reliable for identifying hybrids. F₁ hybrids were readily verified by isozyme patterns of esterase and peroxidase, the zymograms having common and different bands of the parents.