Yoshida - 1981 - Fundamentals of Rice Crop Science

20 FUNDAMENTALS OF RICE CROP SCIENCE
1.18. Cross sections of the leaf blade: A-overview of the cross section of the
blade; B-cross section of large and smallvascular bundles; C-cross section of
the midrib (adapted from Hoshikawa 1975).
other hand, weakly photoperiod-sensitive Peta develops 16–21 leaves and
strongly photoperiod-sensitive BPI-76, 13–23 leaves, depending on the planting
season.
Leaf length increases as leaf number advances. In most varieties, the second or
third leaf from the last is the largest. The last leaf is called the flag leaf.
In cross section (Fig. 1.18), the blade contains many large and small vascular
bundles; stomates are on both sides of the leaf surface, and large air spaces are
developed in the midrib.
In the sheath (Fig. 1.19), large, well-developed air spaces are found between the
vascular bundles. These air spaces are connected to stomates and to air spaces in
the culm and roots, constituting an efficient air passage system from shoot to root.
1.4.2. Growth of single leaves
At a given time, the rice plant is composed of leaves that are physiologically
different in age and activity. Before the initiation of panicle primordia, a leaf
emerges about every 4–5 days; afterwards about every 7–8 days. The rate of leaf