Yoshida - 1981 - Fundamentals of Rice Crop Science

PHYSIOLOGICAL ANALYSIS OF RICE YIELD 241
7.7. Changes in national average rice yields. average yields of
national demonstrations, and the highest yields of national demonstrations
in India during the period from 1968/69-1975/76 (Annual
Report 1976-77, national demonstration trial in India, ICAR).
Japanese weather and soil conditions. Agricultural scientists at the experiment
station, however, were able to produce 9.3–10.2 t/ha when they were allowed to
use the scientific technology at their disposal (Ishizuka 1969). These yields,
almost comparable to yields achieved in the Japan No. 1 yield contest, may imply
that the present rice technology has the same capacity to produce high yields as the
farmer’s long-time and site-specific experience.
A similar record of rice yields can be obtained from India from 1968 to 1975
(Fig. 7.7). Several conclusions can be drawn from the figure:
• The national average yield, slightly less than 2 t/ha, is about one-third the
average yield of national demonstration.
• The highest yield recorded is more than two times greater than the average of
national demonstration.
• The difference between India and Japan lies in the gap between the national
average yield and experiment station yields.
These conclusions indicate that a yield of 5 or 6 t/ha can be achieved with a
moderate amount of inputs and by adopting simple technology provided irrigation
water is available, and yields of 10–12 t/ha are possible under the present weather
conditions if the farmers use more advanced technology.
7.5. ANALYSIS OF HIGH YIELDING CULTIVATION
TECHNOLOGY
This section will first summarize the physiological requirements for high rice
yields based on crop photosynthesis, mineral nutrition, and yield components. It