The experiment was conducted at Agronomy Field Laboratory, Patuakhali Science and Technology University (PSTU), Dumki, Patuakhali during the period from April 2013 to August 2013 to investigate the effects of sowing method on different varieties of Aus rice under tidal ecosystem of Bangladesh.
Six rice varieties (BR 2, BRRI dhan 27, BRRI dhan 48, Kalihaita, Kaliboro and Tepu) were used as planting material.
Seed collection
Seeds of BRRI dhan48 and BRRI dhan27 were collected from Bangladesh Agricultural Development Corporation (BADC), Barisal, Bangladesh and those of Kalihaita and Kaliboro; BR2 and Tepu were collected from the local market of Dumki and Mirzagong, respectively
Data recording
Plant height and tiller number were counted at 15 days after interval from 60 days after sowing to harvesting. Five consecutive hills from each plot exclude the border hills and harvest area were uprooted avoiding border hills and washed them in running tap water. Then the plant samples were carried to the laboratory and plant height and number of tiller were recorded. The following data were collected.
- Crop growth characters
- Plant height (cm)
- Number of tiller hill-1
- Phenological character
- Leaf Area Index (LAI)
- Dry Matter
- Lodging score
- Number of internodes
- Length of lower two internodes (cm)
- Dry weight of lower two internodes (g)
- Diameter of lower two internodes (mm)
- Thickness of lower two internodes (mm)
- Yield and other characters
- Number of effective and non-effective tillers hill-1
- Panicle length (cm)
- Number of fertile spikelets and sterile spikelets panicle-1
- Number of total spikelets panicle-1
- Thousand grain weight (g)
- Grain yield (t ha-1)
- Straw yield (t ha-1)
- Biological yield (t ha-1)
- Harvest Index (%)
- Flooding depth (cm)
- Crop growth characters
- Plant height (cm)
Plant height was measured in cm from the ground level to the tip of the longest leaf or panicle from 60 DAS at 15 days interval from 5 selected consecutive hills. Plant height data was measured in cm.
- Number of tiller hill-1
Number of tiller was counted from 60 DAS at 15 days interval from 5 selected consecutive hills.
- Phenological character
It includes 50% flowering and physiological maturity. These were measured by the visual observation in the field.
- Leaf Area Index
Six random hills plot-1 were selected making sure that the hills were surrounded by living hills. Soil was removed from the hill, taking precautions to keep the leaves from drying and curling before the leaf area was measured. From each hill, the second topmost tiller was used as the simple tiller. The leaf area of all leaves on the sample tiller was determined by Leaf Area Meter. Other green leaves were removed from the hill. The sample leaves and other leaves were dried and weighted separately. Then the leaf area was calculated by the following formula (Yoshida et al., 1976).
Where dry weight of all leaves = dry weight of sample leaves + dry weight of remaining leaves.
- Lodging related parameters
Lodging related parameters were measured from 3 hills collected for measuring LAI. There medium tillers were selected from each selected hill and data were collected from these selected individual tillers. The final data represented the average value of nine selected medium tillers from each plot (Mahabub et al., 2006).
- Number of internode
Internodes number was counted from the base of culm to the panicle neck node.
- Lengths of lower two internode
Length of lower two internodes were measured in cm by using scale.
- Fresh weight of lower two internode
Fresh weight of lower two internode of nine tillers were measured in gram by digital electrical balance.
- Diameters of lower two diameters
Outer and inner diameters of lower two internode were measured in mm by slide calipers.
- Dry weight of lower two internode
Internode of nine tillers were oven dried at 70 0C untilled the constant weight was obtained for recording dry weight.
- Thickness of lower two internode
Outer diameter minus inner diameter of lower two internode gave the thickness of those internodes.
Thickness = outer diameter – inner diameter.
- Dry matter at 50% flowering stage
The plant collected for measuring LAI was used for recording dry matter. The culm of all sample plants was oven dried at 70 0C until the constant weight was obtained for recording dry weight. Then the sum of culm and leaf weight was calculated, to record total dry mater.
- Lodging at 50% flowering, milk stage and maturity
Lodging score at 50% flowering, milk stage and maturity was measured by 1-9 scale as suggested by IRRI (1988) as follows:
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Lodging condition
|
score
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No plants were lodged
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1
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Less than 20% plants were lodged
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2
|
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20-40% plants were lodged
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3
|
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41-60 plants were lodged
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5
|
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61-80% plants were lodged
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7
|
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>80% plants were lodged
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9
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- Yield and yield contributing characters
Yield and yield contributing characters were recorded from 10 randomly selected hills plot-1 outside the harvest area excluding border rows and plants.
- Number of effective tillers hill-1
The panicle which had at least one grain was considered as effective tiller.
- Number of non-effective tillers hill-1
Only the non-bearing tillers were counted from each sample and then average of five samples was taken.
- Panicle length
Length of panicle was measured from each panicle from the first node to the tip of the panicle and then average five of samples was taken & measured in cm.
- Number of grains panicle-1
Presence of any food material in the spikelet was considered as grain. Total number of grains of ten randomly selected panicles was counted. Average mean of grains of these ten panicles was taken as number of grains panicle-1.
- Number of sterile spikelets panicle-1
Grains lacking any food material inside the grain were considered as sterile spikelet and such grains present on the each panicle were counted.
- Number of total spikelet’s panicle-1
The number of grains panicle-1 plus the number of sterile spikelets panicle-1 gave the total number of spikelets panicle-1.
- Thousand grain weight
One thousand grain cleaned dried seeds were counted randomly from the five sample plants of each plot and weighed by using a digital electric balance at the stage the grain retained 12% moisture and the mean weight was expressed in gram.
- Grain yield
Grain yield was recorded from central 5 m2 area of each plot. The grain yield was adjusted to 12% moisture content. Grain moisture content was measured by using a digital moisture tester.
- Straw yield
The fresh weight of straw of 5 m2 was recorded and then representative sample of straw was taken. The sample was oven dried at 70 0C for 72 hours. Then the oven dry weight of straw was calculated in t ha-1.
- Biological yield
Grain yield and straw yields were all together regarded as biological yield. Biological yield was calculated with the following formula and expressed as percentages (%).
Biological yield = Grain yield + Straw yield
- Harvest index
Harvest index is the ratio of economic yield (i.e. grain yield) to biological yield and was calculated with the following formula (Gardner et al. 1985).
- Flooding depth
Depth of water was measured in cm from first flooding to harvesting at 3 days interval by meter scale.