Defoliation of panicled tick-clover, tweedy's tick-clover, and tall bush-clover: i. Winter survival and yields of Nitrogen, herbage, and seed
Few native herbaceous perennial warm-season legumes are available for cultivation in the southern United States. Additional germplasm would be useful for pastures, biomass production, wildlife plantings, rangeland reseeding, or native prairie restoration. Three native perennial legumes were selected from an initial screening of north-central Texas germplasm for potential domestication based on successful establishment, ease of seed harvest, and herbage production. Response to herbage removal was evaluated by measuring forage yield when clipped at 10-, 20-, and 40-cm height (whenever regrowth exceeded 20 cm) over three seasons in 2- by 2-m plots with 0.5 m between plants. Tall bush-clover (Lespedeza stuevei Nutt.) was the slowest to establish but was as productive (P > 0.05) as panicled tick-clover [Desmodium paniculatum (L.) DC.] by the third year (28 g plant–1 at the 10-cm clipping). Panicled tick-clover produced 160 g plant–1 during the second year at the 20-cm harvest, the height at which the greatest (P < 0.05) yields were measured; by the third year at this harvest intensity, the same plants only yielded 27 g. Panicled tick-clover clipped at 20 cm in Year 2 produced the greatest amount of harvested N, 4.44 g plant–1, compared to other entries (average of 0.90 g). Seed numbers, measured in Years 2 and 3, were greatest (P < 0.05) for no-clip bush-clover plants (2470 seed plant–1) during the second year and lowest (4–506 seed) for the panicled tick-clover regardless of clipping or year. These three native North American legumes show some tolerance to herbage removal and potential for both forage and seed production in their region of origin.