Relative growth and nodulation of tropical legume species with contrasting persistence and seedling vigor
1998
Pitman, W.D. | Lai, Z.Q.
Carpon desmodium [Desmodium heterocarpon (L.) DC.] has proven to be a useful perennial pasture legume for some sites in peninsular Florida. However, slow seedling growth rates have made commercial plantings vulnerable to competition from gasses and weeds and to even short periods of drought. Other, less persistent, legumes establish more dependably in the region. Three legume species with contrasting seedling vigor and plant development were evaluated in plantings of mixtures of the three legumes and bahiagrass (Paspalum notatum Flugge). Plant development was monitored to determine if nutritional limitations associated with root development or nodulation impair establishment of carpon desmodium. Every two weeks through the growing season, six plants of each legume in each of four replications were dug to determine shoot dry weight, root dry weight, nodule number, nodule dry weight, and shoot to root ratio. Nitrogenase activity was also assayed by acetylene reduction. Shoot, root, and nodule weights and nodule number were substantially lower for carpon desmodium during early seedling development than for phasey bean [Macroptilium lathyroides (L.) Urb.] or aeschynomene (Aeschynomene americana L.). Nitrogenase activities per gram of nodule were highly variable with no differences detected among species or sampling dates. Nodules were much slower to develop on carpon desmodium than on the other two species, and this delayed nodulation is suggested to be a major limitation in development of seedlings of this species.
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