Rescue of Photoperiod/Freeze-Sensitive and Low Seed Producing Accessions of Lablab Purpureus Using Hydroponic Cloning and Aeroponics.

Hyacinth bean, Lablab purpureus is a legume used as a vegetable and the USDA, ARS, PGRCU conserves 137 hyacinth bean accessions from countries worldwide. Many accessions in this collection are photoperiod and freeze-sensitive due to their flower and seed production during November through March in the Byron and Griffin, GA environments. Other hyacinth bean accessions produce very few seed when regenerated in the field. To determine if hydroponic cloner/aeroponic systems are useful for regenerating seed from these types of environmentally sensitive and low seed producing hyacinth beans, more than 20 photoperiod and freeze-sensitive hyacinth bean accessions were directly seeded at the USDA, ARS, PGRCU research farm in Byron, GA during the 2011 summer growing season. Four woody and mature vegetative stem cuttings (15-20 cm in length)/accession with 3 true leaves/cutting were removed from plants that did not flower nor produce seed within each accession and placed in a hydroponic cloning system inside a greenhouse near the end of the field growing season during the Fall of 2011. Most of the stem cuttings developed very healthy root systems after 1-2 weeks of cloning. Two to 4 well developed stem cuttings/accession with healthy root systems were then transplanted to potting soil in plastic pots and placed in a greenhouse. One hyacinth bean accession which produces very low seed numbers in the field was evaluated for its regeneration capacity when grown in a high tunnel enclosed aeroponic system during the 2011 summer season at Griffin, GA. Fourteen 30 day old seedlings from this very low seed producing hyacinth bean accession growing in 6.4 cm x 7.0 cm jiffy pots containing potting soil/seedling were placed in an aeroponic system inside a high tunnel during the first week of May, 2011. Currently, high quality seed numbers reaching 200 seeds/accession have been regenerated from clones while more than 1,500 seeds were successfully regenerated from the aeroponically and normally low seed producing hyacinth bean accession (when grown in the field). These are excellent techniques to rescue photoperiod/freeze-sensitive hyacinth bean accessions for seed regeneration and to produce quality seed from field grown low seed producers. Hydroponic cloning and aeroponic systems such as these will provide useful tools that are applicable to many other crop species with similar environmental sensitivities and low seed producing accessions.