Management of rice production systems to increase productivity

At low fertility levels such as at Zero and Low‐input application rates
there was stunted growth and wilting as well as high incidence of crop loss
due to termite attack. The plants growing under high and very high
application rates were significant more tolerant to wilting and termite attack.
Spikelet fertility (Table 9) was low at zero fertilizer application for all the
varieties with the exception of cv WAB 56‐125. The local check Peking was the
most affected at zero and low fertilizer application rates. Spikelet fertility was
low at very high fertilizer application rate due to blast infestation. Stover
weight at zero application, low‐input, and high‐input level were not
significantly different for all varieties. At very high input though, there was a
significant difference. Yields were highest for all varieties at high application
rate. WAB 56‐125 gave 2.9 t/ha, which is relatively the highest yield at the
different application rates. Yields were low at the zero and low‐input levels
because of poor plant stand due to termite attack. At low N application,
seedling vigor was poor, and the weak stems were highly susceptible to
termite infestation and damage. Precipitation was unevenly distributed
during the growing season. Seventy‐five percent of the rains fell during the
last decade in August and the first and second decades of September. Severe
drought was experienced between emergence and panicle initiation.
Development of the panicle is very sensitive to soil water availability, and the
rate of development is reduced with a small water deficit and ceases
completely with the development of severe drought.
Weed infestation was relatively lower in 2002 than in previous years.
It is apparent from the results that the low‐input varieties did much better at
the high fertilizer application rate of 80‐40‐40 kg/ha NPK. Under the drought
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