Agriculture Reference
In-Depth Information
(Murayama 1967). In other words, the effi ciency of producing
spikelets per unit nitrogen or dry weight is much higher in
cool regions than in warm regions. In a controlled environment
experiment where light intensity was kept high and plant
nutrients were abundantly supplied lower temperature during
the reproductive stage produced more spikelets (Yoshida
1973b).
Low temperature is a cause of sterility in cool regions.It
is evident that air temperature as low as 15ºC to 19ºC at the
meiotic stage of pollen mother cells formation causes very high
sterility. This occurs in areas at high altitude in the temperate
region and also at high altitudes of the tropics. Temperatures
lower than the optimum may delay ripening and eventually
fi ll grain percentage (Wada 1969).
In Ethiopia along the altitude at 3 places viz. Eladale (1616
masl, 28.4/12.4ºC), Gomma² (1497 masl, 29.5/13.5ºC) and Shebe
(1420 masl, 30/14ºC) 14 varieties of rice are being grown. Yield
and yield components suggest that there is a drastic reduction
in grain yield at Eladale along with the panicles per plant and
grains per panicle as well as 1000 grain weight. However,
grains per panicle are strongly and positively correlated with
the grain yield (0.847) only (Tables 36 & 37).
Table 36
Yield and yield components in three locations in Ethiopia.
(Mean value)
**
Location Panicles per plant Grains per panicle 1000 grain wt (g) Grain yield(Kg/ha)
**
Eladale 6.01
22.49
23.82
749.98
Gomma 2 7.01
77.07
25.00
3092.38
Shebe
10.52
123.38
28.35
5184.44
