Evaluation of Cowpea Germplasm for Texas Double Cropping Systems.

Cowpea (Vigna unguiculata [L.] Walp) is a diverse legume that serves many purposes. The species varies by seed color, seed size, maturity, physical appearance and production traits. The objective of this study was to identify cowpea plant introduction germplasm lines with improved seed and biomass production in a double-cropping system with forage rye. Our target for cowpea maturity was mid to late September. In the first year of the experiment, 37 lines were grown in a greenhouse at Overton, TX, and were screened for maturity and seed yield. Based on these traits, 17 lines were selected for field evaluation. These selected lines and two check cultivars, ‘Iron and Clay’ and ‘Combine’, were grown in 2015 on a Darco loamy fine sand in a randomized complete block design at Overton, TX. Data collected included total dry matter production and seed yield. Data were analyzed using SAS^® PROC MIXED. Least square means were separated using the Tukey-Kramer adjusted LSD’s. When comparing the lines there was no difference in biomass production (μ = 10,372 kg ha^-1; P = 0.22). The entry that had the largest seed yield was entry 16 (2194 kg ha^-1) and it was different (P < 0.01) from intermediate lines; whereas, lines 19, 31, 32, 11, 30, 21, and 24 had the lowest yields (averaging 111 kg ha^-1). Iron and Clay and Combine did not produce high seed yields compared to other entries and had lower biomass contributions. The total production comparisons were the sum of the biomass and the seed yields, no significant (μ = 11,271 kg ha^-1; P = 0.20) differences among entries were noted. Cowpea plant introduction lines were identified with potential to improve Texas cowpea and forage rye double cropping systems.