Submitted to: Germplasm Release
Publication Type: Germplasm Release
Publication Acceptance Date: January 4, 2010
Publication Date: January 4, 2010
Citation: Harrison Jr, H.F., Fery, R.L., Thies, J.A., Smith, J.P. 2010. Notice of Release of US-1136, US-1137, and US-1138 Cowpea Gerplasm Lines with Potential For Use As A Cover Crop. Germplasm Release. U.S. Department of Agriculture, Agricultural Research Service, Washington, D.C. 20350, January 4, 2010. Technical Abstract: In 1998, field screening trials were initiated to identify cowpea (Vigna unguiculata L.) populations suitable for use as a weed-suppressing cover crop. After the preliminary field studies, eleven populations were selected for more detailed evaluations. After three additional years of evaluation, eight of the eleven populations were eliminated due to poor seed quality or disease susceptibility. The remaining three populations were identified for development for use as a cover crop. The three populations are land races that were collected in South Carolina. The three land race populations were grown in a 2006 field planting and each population was carefully evaluated for the following traits: rapid growth, good vigor, indeterminate growth habit, canopy height, and high seed quality. A pure-line selection procedure was executed, i.e., single plants were selected from each population. A single pure line population from each of the three original land-race populations was selected for release as germplasm lines. The selected plants were progeny tested in 2007 and found to be uniform in all important characteristics. The newly released lines, US-1136, US-1137, and US-1138 have relatively short photoperiods; flowering does not begin until day length is approximately 13 hours, and flowering and pod set continue in an indeterminate manner until plants senesce in late autumn or are killed by frost. The lines are homozygous for all important agronomic traits. They are resistant to the southern root knot nematode [Meloidogyne incognita (Chitwood) Kofoid and White], and all grow well without nitrogen fertilization. Iron Clay and other forage cowpea cultivars produce seeds with an impermeable seed coat. This trait enables viable seeds to overwinter in the soil, germinate the following spring, and become a weed in subsequent crops. The newly-released lines produce good quality seeds with high germination rates (>95%) and do not produce seeds with impermeable seed coats. The adoption of these lines for use as a cover crop will eliminate the weed problem caused by overwintering cowpea seeds. Samples of seeds of US-1136, US-1137, and US-1138 are available for distribution to all interested research personnel.