Environmental Differences in Leaf Stomatal Frequency of Rice

Stomatal frequency (stomatal number per unit leaf area, abbreviated Sf) of a flag leaf was high at the middle of the leaf and low at the leaf margin. It was low at the leaf base and the leaf apex (Fig. 1, 2). Sf in a leaf in upper leaf position on a stem was higher than that in lower leaf position. Sf in lower leaf surface was higher than that in upper leaf surface (Fig. 3). 2. Sf of upland rice cultivars was lower than that of lowland rice cultivars (Fig. 3). Sf of Indica type rice was higher than that of Japonica rice (Fig. 4, 6). Sf of leaves grown in different years (Fig. 4), in different transplanting dates (Table 4) and in low-land and upland field (Table 3) correlated highly in positive way. Sf of L2 and Lf (Table 2) and Sf in lower and upper leaf surface (Table 3) correlated highly also in positive way. 3. Fertilizer application at lag stage caused an increase of Sf leaf size and total stomates of a flag leaf (Table 1, Fig. 5). Sf decreased with a shortening of the growing period (Table 5, 7). In comparison among cultivars of lowland rice, Sf of cultivars having a large leaf was high (Table 5). But in comparison among cultivars containing upland rice, Sf of cultivars having a large leaf was low (Table 7). Values of genetic correlation between Sf and leaf size (Table 6) explained this tendency quite well. Values of environmental correlation between them were low (Table 6). Sf of lowland rice grown in lowland field was higher than that in upland field. In case of upland rice, however, difference between Sf grown in lowland and upland field was not so clear (Fig. 3).