Agriculture Reference
In-Depth Information
can expedite the bridging of yield gaps, thus improving the
productivity and effi ciency of rice production (Dunayri et al.
1998) (Table 23).
Table 23 Comparative national average yields, irrigated rice yields and
experimental station rice yields, Asian countries, 1991.
Countries
National average
rice yield (t/ha)
Irrigated rice yield
(t/ha)
Average Potential rice
yield (t/ha)
Bangladesh
2.6
4.6
5.4
China
5.7
5.9
7.6
India
2.6
3.6
5.9
Indonesia
4.4
5.3
6.4
Nepal
2.5
4.2
5.0
Myanmar
2.7
4.2
5.1
Philippines
2.8
3.4
6.3
Thailand
2.0
4.0
5.3
Vietnam
3.1
4.3
6.1
Rice production is affected severely due to cold from place
to place and year to year, ranging from 10 to 50%. The yield
reduction is mainly due to reduction of one of the main yield
components namely the spikelet fertility which minimizes the
number of fi lled grains in the spike. It is also noted that the
other yield components such as panicle number per m² and the
panicle length were affected due to panicle exsertion problems.
Grain fi lling is also affected, as there are partially fi lled grains
reducing the average 1000 grain weight. It is well known that
the relationship of yield and yield components for rice may
be given as Yield (g per m²) = panicles per m² X number of
spikelets per panicle x grain fertility % x 1000 grain weight(g) X
10 -5 . The yield components are often positively and negatively
correlated with the yield depending on the situation. It is well
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