Vergara - 1976 - Physiological and morphological adaptability of ri

38 CLIMATE ékND RICE
While there is a “grain” of truth in each of these common assertions about
rice, it is clear that a rice specialist could argue with and find exceptions to each
of the statements.
The geographer studying rice is. by definition. more concerned with questions
regarding the spatial pattern of suitable climates on the surface of the earth
than with precise definition of the optimum conditions for growth. A close study
of the tvorld map of rice production and maps of rainfall and temperature patterns
indicates that few rice-producing areas meet all of the criteria commonly
set forth, and that in some cases rice is being successfully raised in areas which
as recently as the 1950s tvere identified as "beyond the limit of nee production."
Can it be that breeding programs have been successful enough to extend the
range of climates suitable for rice production‘? Or perhaps technological i11-
novation has been responsible for the development of methods suitable for
overcoming the limits of problem climates? At any rate. the range of climates in
which rice was produced in I974 is very great indeed.
The map reveals that rice is cuirently raised in central Czechoslovakia at
latitude 50° north and in central Sumatra on the equator. It is raised at Akyab.
Bumia. during a growing season with over 4.500 mm of rainfall and at Al llufuf.
Saudi Arabia, during a growing season with 100 mm of rainfall. Success is also
achieved at Sukkur. Pakistan, where temperatures through the growing season
average 33°C and at Otaru. Japan where. according to Wadaehi (1958). the
growing season averages 17°C. Rice is also raised under a broad range of solarenergy
conditions, from Singapore where the crop is subject to only 50 kilolanglefrs
of solar radiation to the Nile Delta where Landsberg et al. (1963) indicates
a rice crop receives about 95 kilolangley-"s.
WHAT IS A RICE CLIMATE‘?
With rice being produced under such a wide range ofclimatie conditions. perhaps
“What is a rice climate?" is not the most important question to ask. Perhaps
we should redirect our attention to the site of the original domestication in
the hope that we can identity the climatic conditions best suited to the crop as it
was originally produced.
It has already been brought out that the weight of evidence points toward a
site in present-day’ Burma or Thailand. This site was most probably’ at an interior
location outside of the great delta regions of the Irrawaddy, Salween. and Chao
Praya Rivers. Primitive man did not have the technology to permit pennancnt
settlement and the development of agriculture on vast plain areas subject to periodic
flooding of considerable depth. The Oflglfliil settlements undoubtedly were
in areas tiffering a wide range of plant and animal associations within a limited
range. Such a site offered a variety of food ‘sources over a span of seasons to a
societyt dependent upon hunting and gathering for its food supply. Sauer (1952)
feels that a site close to the edge of the uplands but on gently rolling topography
and close to a river providing a reliable water supply appears most likely’. For