Tropical Grasslands (1989) Volume 23, 240249
YIELD, PERSISTENCE AND DRY MATTER DIGESTIBILITY OF SOME C3, C4 AND C3/C4 PANICUM SPECIES
KAREN HILL1, J.R. WILSON2, H.M. SHELTON1
1Department of Agriculture, University of Queensland, St. Lucia 4067
2CSIRO Division of Tropical Crops and Pastures, 306 Carmody Road, St. Lucia 4067
Three Panicum species of C3 type (non-Kranz leaf anatomy) and 1 species of C3/C4 type (intermediate anatomy) were compared in the field with 2 commercial C4 Panicum species (Kranz leaf anatomy) to determine whether any of the C3 or C3/C4 species have agronomic or nutritional characteristics which would make them prospective plants for use in tropical pastures. Parameters examined were total and seasonal yield, percentage leaf and dead material, density of inflorescences, persistence and weed invasion, and dry matter digestibility of young leaves. The species were grown in a sub-tropical environment under irrigation and high nitrogen fertilisation.
Panicum maximum var. trichoglume cv. Petrie and P. coloratum cv. Bambatsi (C4 types) were clearly superior for most agronomic attributes, and the former in nutritive value. Of the C3 type species, only P. laxum exhibited favourable agronomic qualities, forming relatively short, spreading and persistent, weed-free swards with cumulative dry matter yield over the 17 months about 65% of that of the C4 species; it also seeded freely. However, dry matter digestibility of P. laxum leaves was only 49–54%, comparable in level to that of P. coloratum but considerably lower than that of P. maximum var. trichoglume (60–73%). P. decipiens (C3/C4 type) was persistent, but it exhibited little spreading and its yield was only 80% of that of P. laxum. Leaf dry matter digestibility of P. decipiens was similar to that of P. laxum. The other C3 Panicum species exhibited very low yields, limited seeding ability, and poor persistence.
P. laxum was the only one of the C3 and C3/C4 species which may warrant further testing to assess its commercial potential.