Stomatal Length, Frequency, and Distribution in Bromus inermis Leyss I 1

Octoploid (2n = 56) bromegrass ( Bromus inermis Leyss.) had significantly larger but fewer stomata than tetraploid (2n = 28) plants at all leaf positions sampled and on both leaf surfaces. Both ploidies showed a similar pattern of stomatal length and frequency at four positions on the culm and three positions on the individual leaf. Stomatal length increased and frequency decreased progressively from the top (LI) to lower (IA) leaves. The tip of the leaf had the largest but fewest number of stomata with the reverse for the base of the leaf. Seven bromegrass cultivars within the octoploid level differed significantly in stomatal length and frequency of adaxial and abaxial surfaces and at five different leaf positions on the culm. ‘Carlton’ and ‘Blair’ had consistently smaller stomata with greater frequency, whereas ‘Saratoga’ and ‘Red Patch’ had larger, but fewer, stomata. Stomatal length increased while frequency decreased from L1 to L3 and leveled off from L3 to L5 (fifth leaf below panicle). Varietal differences in stomatal length and frequency were mainly associated with the center position of a leaf surface. Correlations between the adaxial and abaxial surfaces of L1 showed highly significant positive values for both stomatal length and frequency. Stomatal length and frequency were negatively associated at either surface of LI. The ratio length ✕ frequency was affected more by stomatal frequency than length on the same leaf surface. The interrelationships among stomatal and leaf characters and tiller dry weight suggested that a cultivar with lower stomatal frequency is likely to have larger stomata, longer and wider leaves, and greater dry weight/tiller.