The growth of Bothriochloa pertusa and Dichanthium annulatum in relation to crowding and herbage removal [fodder grasses, feed grasses, yield]

The response of the two closely related sympatric fodder grasse, Bothriochloa pertusa (L.) A. Camus and Dichanthium annulatum (Forsk.) Stapf to increasing density and herbage removal has been compared. Both the species showed predominantly plastic reaction to density although at highest density (32 plants per pot of 25 cm diameter) some mortality, 9% in D. annulatum and 6% in B. pertusa, was also observed after 6 months growth. Increase in density from 1 to 32 plants per pot caused substantial decrease in production of tillers, leaves, above ground herbage and total biomass of both the species. There was also some delay in flowering, and the percentage of fertile tillers was greatly reduced owing to increasing density. In the case of D. annulatum, a great reduction was noticed in the number and length of rhizomes and allocation of dry matter to them at higher densities. In general, the plastic reduction in various growth parameters due to crowding was comparatively greater in D. annulatum. In both the grasses, the maximal yield was achieved when 4 plants per pot were grown. With an increase in density from 1 to 4, there was some increase in yield but this was never in proportion to increase in plant number per unit area. Any increase in density beyond 4 resulted in decreased yield per pot. Both the grasses recovered well from the single treatment of clipping at 5 cm height which was done to simulate grazing. In terms of aboveground biomass production, D. annulatum seems to have suffered greater setback due to clipping than B. pertusa. The effect of crowding on the production of aboveground herbage appears to have been minimised due to clipping treatment.