Kumara KHCH* and Hafeel RF
Rice Research Station, Department of Agriculture, Ambalantota, Sri Lanka
Abstract
Grain filling rate, yield and 1000 grain weight are very important traits to
determine the different nitrogen levels of response for different rice
varieties. This study will investigate the rate of grain filling, grain
yield and 1000 grain weight, and some quality parameters of one elite
breeding line (At 08 1078) and standard variety (At 362) grown at five
different nitrogen (N) levels (0, 50, 100, 150 & 200 kg N ha-1 ) under
irrigated water condition in the low country dry zone of Sri Lanka. A
split-plot experimental design was used in this experiment with three
replicates. The gross plot and net plot area were 18 m2 and 12.96 m2 of each
experimental unit. Main plots were separated by a ridge (40cm in width). The
thousand-grain weight of each experimental unit from heading to harvesting
was recorded at the 4-day interval to inspect the grain filling rate.
Irrespective of the variety, grain filling commenced after four days from
the day of heading and the rate of grain filling depended on the rate of
nitrogen application on each experimental unit. Rice fertilized with ≥100 kg
N ha-1 had a high grain filling rate and the period of grain filling
increased in both varieties. Application of 100 kg N ha-1 was recognized as
the optimum level for grain filling. Further increment of soil nitrogen (150
or 200 kg N ha-1 ) has not significantly affected the grain filling rate of
the paddy. In addition, the significant highest grain yield, grain hardness,
brown rice content, grain length and width were recorded at 100 kg N ha-1.
It can be concluded that the N level of 100 kg N ha-1 was found for yield
response and grain filling to be the best rate for both elite line At 08
1078 and the variety At 362.
Keywords:
Grain filling, Grain weight, Growth parameters, Nitrogen,
Rice
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