| dc.description |
Leaf surfaces of seven genotypes of Sorghum bicolor, two of maize, Zea mays, and two pearl millet, Pennisetum americanum, were examined by scanning electron microscopy for possible morphological differences. Leaves 1, 3, 5 and 7 were photographed and prints were used to estimate waxiness, hairiness or pubescence and stomatal density. Glossiness was determined by spraying water, which adhered to the glossy leaves. Cuticular transpiration of detached third and fifth leaves was estimated from the rate of water loss after abscisic acid induced stomatal closure. Sorghum lines SC283, CSM63, CSM90, and pearl millets Souna and Tiotioni (all from Mali), were non-glossy, well covered with wax, and exhibited variable hairiness. Older leaves of sorghum varieties Martin and Redlan were glossy and, like older leaves of the other glossy lines SC1096 and SC90, had little or no wax deposits on their cuticles. The two maize cultivars, NB611 and N7A, were non-glossy with dense wax covering; no trichomes were observed until the 5 to 7 leaf stage. Thus, the glossy character was correlated with the reduction or absence of wax deposits on the leaf surfaces, while hairiness might occur in either glossy or non-glossy genotypes. Unlike sorghum and maize, in which all leaves after the fifth or seventh were glossy, pearl millet showed no glossiness through the ninth leaf. Measurements showed that cuticular transpiration of glossy leaves was often more than double that of non-glossy leaves. Comparisons among sorghums showed that non-glossy lines had higher stomatal densities than glossy lines. |
