Heritability of Stomatal Density and Distribution on Leaves of Grain Sorghum 1

Stomatal density was recorded on every leaf of plants sampled from six varieties of grain sorghum, Sorghum bicolor (L.) Moench, and their 15 F1 hybrids. The plants were grown in the field at two locations in Kansas. Stomatal density on abaxial leaf surfaces was highest at the basal portion of the leaves. Heterosis was not observed when stomatal densities of parents and hybrids were compared. Among the 15 uppermost leaves, the second leaf from top had the highest density, and leaf no. 15 had the lowest. Stomatal density was higher on abaxial surfaces than on adaxial sides. Heritability estimate for stomatal density was high. That high befitability and little heterosis were observed for stomatal density supports the general principle that traits showing little or no heterosis tend to have high heritabillties. Total stomatal number per plant was higher in hybrids than in parents; the difference was attributable to more leaf‐blade area. Stomata on abaxial surfaces were longerthan those on adaxial surfaces; hybrids tended to have longer stomata than did parents. Grain yield per unit leaf area and per 10 6 stomates showed a similar trend: the performance of progeny resembled that of their parents. However, neither leaf area nor total stomatal number was significantly correlated with grain yield. Stomatal density was negatively correlated with grain yield and with stomatal length; total stomatal number was positively correlated with total leaf blade area.