Yoshida - 1981 - Fundamentals of Rice Crop Science

90 FUNDAMENTALS OF RICE CROP SCIENCE
2.16. Schematic diagram showing shortwave
radiation balance of paddy field.
Photosynthetically active components
are indicated by hatched part. Leaf area
index = 5.0 at heading (Kishida 1973).
Table 2.12. Photosynthetic efficiency (( E µ ) of field rice crops.
Total dry matter
or grains E µ (%) Reference
Maximum Short-term Total dry matter 3.7 Murata et al (1968)
Maximum Short-term Total dry matter 3.32 Kanda (1975)
Mean Whole growth Total dry matter 1.25 Kanda (1975)
Mean Whole growth Grains 0.48 Kanda (1975)
(CGR) can be estimated if E µ , S, and K are known:
CGR (g/m 2 per day) =
E µ × S × 10 –4 ,
K
(2.9)
The heat of combustion values vary with plant parts (Table 2.13). In the IBP
report, a value of 3,750 cal/g was adopted for all plant parts. This value is perhaps
representative for vegetative parts. If 3,750 cal/g is adopted for K , along with the
highest mean E µ value of 3.00%, an expected maximum crop growth rate under
incident solar radiation of 400 cal/cm 2 per day would be:
Maximum CGR = 0.03 × 400 × 10 4 = 32.0 g/m 2 per day. (2.10)
3750
Thus, it is possible to estimate a maximum crop growth rate for rice when incident
solar radiation is known.
2.4.4. Estimation of maximum potential yields
Estimation of maximum potential yields is important in that it tells how far we can