Yoshida - 1981 - Fundamentals of Rice Crop Science

GROWTH AND DEVELOPMENT OF THE RICE PLANT 27
1.25. Cross section of an upper internode
Several plant height characteristics are measured in agronomic investigations:
plant height, culm height, and crop height. Plant height refers to the longest
distance between the plant base and the tip of the highest leaf (or panicle,
whichever is longer). Rice leaves, usually bent, are stretched along the culm axis
for plant height measurement. Culm height is the length between the plant base and
the panicle necknode. It is considered a more meaningful measure than plant
height when lodging resistance is to be examined. Crop height may be defined as
the length between the ground surface and the highest point of the crop canopy.
1.5.2. Internode elongation
Internode elongation is closely associated with growth duration (Hosoda and
Iwasaki 1960, Vergara et al 1965). In early- and medium-maturing varieties, it
usually starts around panicle primordia initiation. In late-maturing varieties, it
starts before panicle primordia initiation. In photoperiod-sensitive varieties,
extended photoperiod increases the number and total length of internodes. In
photoperiod-insensitive varieties. it has no influence on internode elongation.