Agronomy and Horticulture Department


Date of this Version



Published in Physical Review Volume 179, Number 3, 15 March 1969. Copyright 1969. Used by permission.


Recent advances in crop physiology have given us some clues for analysis of the complex relationships of environmental factors, cultural conditions and genetic factors to crop yield. However, in order to accomplish this analysis, it is quite necessary to have concrete knowledge about the causal relationships and the time sequence of the processes of yield-formation.
In grain crops, the process of yield-formation may be divided into the following three phases:
1) Formation of organs for nutrient absorption and photosynthesis,
2) Formation of flower organs and "yield-container," and
3) Production, accumulation and translocation of "yield-contents."
The effect of nitrogen, which has been quite popularly used to promote the growth of crop plants, also will be expressed through these processes.
In the following presentation, an attempt has been made to demonstrate the pattern and meaning of physiological responses of crop plants, especially of rice plants (Oryza sativa L.), to nitrogen as associated with their grain production, putting emphasis on the second and third phases.