Abstract
Two genotypes of kenaf (Hibiscus cannabinus L. : cv. Yuefeng 1 and a National Agriculture Research Center (NARC) strain) were cultivated in 1999 and 2001 to determine and compare growth and morphological features. NARC strains were harvested on October 28 and 29 in 1999, and on July 3, July 25, September 7 and October 11 in 2001. Yuefeng 1 plants were harvested on November 5 in 2001, and on July 3, August 9, September 7 and October 11 in 2001. In 2001, photosynthetic rates of upper leaves, and crude protein and mineral concentrations of all leaves were analyzed. In both years, plant height and the number of nodes were measured during the cultivation periods. Rates of increases in plant height and the number of nodes in the NARC strain declined at 120 days after sowing (DAS) and the number of main stem leaves decreased remarkably thereafter. Photosynthetic rates of the upper leaves of both genotypes measured under a photosynthetic photon flux density of 1600 μmol m-2 s-1 were markedly high for C3 species, with the NARC strain in particular attaining a rate of 39.4 μmol CO2 m-2 s-1. Leaf protein concentrations of both genotypes decreased with growth, with a marked decrease in the NARC strain from 80 DAS onward. The calcium concentration of kenaf leaves increased with growth, but concentrations of Na and K decreased. It is concluded that these leaf characteristics make kenaf a potentially valuable forage species.
