The experimental treatments consisted with two factors i.e. variety as planting materials and transplanting date (date) as experimental treatment.
The seeds of two T. aman rice genotypes namely BRRI dhan–46 and BINA dhan–7 were used as planting materials for the present study.
Four different transplanting dates viz. July 12, July 27, August 12 and August 27 were applied in this study as treatments of the present study. The two factors experiment were indicated as below
Factor A (Transplanting date)
D1: 12 July (1st transplanting)
D2: 27 July (2nd transplanting)
D3: 12 August (3rd transplanting)
D4: 27 August (4th transplanting)
Factor B (Varieties)
V1: BRRI dhan–46
V2: BINA dhan–7
So, the treatment combinations are (Factor A × Factor B)
D1×V1: 12 July × BRRI dhan–46
D2×V1: 27 July × BRRI dhan–46
D3×V1: 12 August × BRRI dhan–46
D4×V1: 27 August × BRRI dhan–46
D1×V2: 12 July × BINA dhan–7
D2×V2: 27 July × BINA dhan–7
D3×V2: 12 August × BINA dhan–7
D4×V2: 27 August × BINA dhan–7
The two factors experiment was laid out a two factors Randomized Complete Block Design (RCBD) with three replications assigning the dates of transplanting in the main plots and varieties in the sub plots. Each replication was divided into six unit plot. There were 18 unit plots (transplanting 3 × varieties 2 × Replication 3). The size of unit plot was 4.0 × 2.5 m where block to block and plot to plot distance was 1.0 and 0.5 m, respectively. Row to row and plant to plant distances were 20 × 20 cm (recommended spacing) in each plot. Sampling was done at 30 days interval from 30 DAT up to 90 DAT and at harvest for morpho–physiological data while yield and yield contributing data were recorded only at harvest.
Parameters studied
- Plant height (cm)
- Number of leaves per plant
- Leaf area per plant
- Leaf area index
- Number of total tillers per hill
- Number of effective tillers per hill
- Number of non– effective tillers per hill
- Panicle length
- Number of total grains per panicle
- Number of filled grains per panicle
- Number of unfilled grains per panicle
- 1000–grain weight
- Grain yield
- Straw yield
- Harvest index
-
Leaf area index
The leaf area of one hill was measured by an automatic leaf area meter. Leaf area of the rest five hills were calculated from the leaf dry weight of respective hills multiplying with the ratio of the leaf area of measured hills and its dry weight. Then the leaf area was expressed as average of five. Finally leaf area index (LAI) was calculated as follows–
Where, LA = leaf area (cm2), P = ground area (20 cm × 20 cm = 400 cm2 plant–1)
Harvest index
Harvest index is the ratio of the economic yield to the total biological yield of a crop. The harvest index was calculated by using the following formula:
Harvest index (%) =
Where,
Economic yield = Grain yield
Biological yield = Grain yield + Straw yield
Analysis of variance was done following the Randomized Complete Block Design with the help of MSTAT–C package programme developed by Russel (1986). The mean differences among the treatments were evaluated with the help of Duncan’s Multiple Range Test (DMRT) test at 5% level of probability (Gomez and Gomez, 1984).