Management of rice production systems to increase productivity

This causes fluctuation in both yield and area under cultivation from
year to year. Yields of rice in rainfed systems are always subject to the
vagaries of the monsoon. Their yields are invariably lower than for irrigated
rice, and the magnitude of yield lost due to water shortage depends on the
degree of stress and on the time at which the water stress occurs (Greenland,
1997).
Environmental concerns and increasing human density have led to
research on permanent cropping of the land. One strategy to facilitate
cultivation of the same piece of upland rice field without high input of human
and fossil energy, nutrients, and chemicals is the use of low‐input rice
varieties. This is a major challenge for research because upland rice often
needs a higher level of fertilization than does lowland rice. Nitrogen is most
often the limiting nutrient and is required in the greatest quantity for rice
production. The nitrogen effect is manifested quickly on plant growth and
ultimately on crop yields. Hence, the fertility status of a soil depends to a
great extent on the nitrogen status of the soil (Sinha and Prasad, 1980).
High input costs, low yields and low prices for rice constrain upland
rice production in The Gambia and other West African nations. Low prices
for rice have in fact placed farmers all over the world in a cost‐price squeeze.
There is an urgent need for cultivars and production technologies that will
help increase yield at lower monetary cost (De Datta and Broadbent, 1988).
Drought tolerance and nitrogen‐responsiveness are recognized as desirable
characteristics of crop plants in breeding for high‐yielding cultivars in semi‐
arid regions (Otoo et al., 1989).
African rice varieties are generally well adapted to the major stresses
found in upland areas. When grown under non‐intensive management these
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