Vergara - 1976 - Physiological and morphological adaptability of ri

40 Guitars AND RICE.
In the study of phenomena which are uneven in their distribution it is often
easy to identify the core area or center of focus. It is also relatively easy to
identify the outer limits or the fringe areas-problems of classification are most
difficult in the traditional zones between the extremes. For example, in a drive
from the IRRI compound to the Manila Hotel. when does one enter the urban
area? Clearly the Manila Hotel is at the heart of the city, the core area, and
IRRI is outside of the city, but where are the intermediate boundaries?
The same kind of problem is involved in the study of climate and rice. The
core area can be identified, as has been attempted above. and the location of
climatic analogues the ‘WDTld around can be mapped. In these areas rice can be
raised without reliance on energy inputs other than for traditional farming
practices such as plowing. planting. and harvesting. The climate is such that a
crop can almost alvrays be brought to harvest without the addition of water other
than that provided by the rainfall. Temperature ranges are almost never so great
as to destroy a crop. The growing season is of ample duration to allow the use of
varieties requiring 180 days or more. Rainfall decreases sharply at the end of
the season to provide good conditions for the ripening and harvest periods. In
such areas and under the conditions provided by nature alone, yields are modest
but the important point is that they are reliable year after year. Failure of the
crop is uncommon. It is true that in areas such as this, man and his technology
can provide nature with a great deal of help, but record crops have never been
achieved in such areas and perhaps never will be achieved largely; because of the
relatively’ low levels of solar radiation.
At the opposite end of the continuum are areas such as the Nile Delta, Pakistaifs
Sind, northem Hokkaido, and Manchuria. In these areas rice production
would be impossible in most years without man's intervention through
major engineering works and the expenditure of great amounts of energy. In the
Nile and in Sind nature is so stingy with her precipitation that rice cultivation
(and in fact cultivation of any kind) tvould be impossible if man did not find
wayts to provide adequate water. Temperatures are high, relative humidities are
ltnv. and the potential evapotranspiration rates are the highest in the world.
Water demands for a rice crop in such areas are almost double the needs of the
same crop in the core area.
To provide the sorely needed water, man must intervene and modify the conditions
provided by nature. Water is provided by diverting the flow of extitic
rivers. themselves out of place in such an environment. and dependent for their
flow on moisture provided by nature in sharply coiltrasting ecosystems hundreds
or even thousands of miles from the irrigated area. Water is moved to the paddy
fields ihrough a complex system of dams, reservoirs, canals, siphons, and
ditches, all of vahich were built and are maintained through the expenditure of
vast amounts of energy’. chiefly’ derived from fossil fuels. In other desert environments
the ‘water is pumped from underground supplies many of which have
been accumulated over eons of time and which are non-renewable in the life of
man.