The present study was conducted at the Research Farm of Patuakhali Science and Technology University, Dumki, Patuakhali during the period from July 2013 to December 2013 to select the most optimum ages of seedling and most productive variety on the aspect of growth and yield of selected Moulata and Dudkalam varieties.The experiment treatments consisted with two factors i.e. variety as planting materials and seedling number per hill as seedling treatment. The seeds of two T. aman rice varieties namely Moulata and Dudkalam were used as planting materials for the present study as level factor A.
The selected T. Aman rice varieties are-
Factor-A (Variety)
V1: Moulata
V2: Dudkalam
Three different ages of selected T. aman rice seedling were used as treatment for the present study as level factor B. They are as follows:
Factor-B (Treatments)
T1: 30 day old seedling
T2: 45 day old seedling
T3: 60 day old seedling
So, the treatment combinations are (Factor A × Factor B)
V1×T1: Moulata × 30 day old seedling
V1×T2: Moulata × 45 day old seedling
V1×T3: Moulata ×60 day old seedling
V2×T1: Dudkalam × 30 day old seedling
V2×T2: Dudkalam × 45 day old seedling
V2×T3: Dudkalam ×60 day old seedling
Experimental design and layout
The experiment consisted of two rice varieties and three types of age of seedling treatments and was laid out a two factors split–plot (Variety in the main plot and seedling age in the sub–plot) in Randomized Complete Block Design (RCBD) with three replications. The size of 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 also 20 and 20 cm, respectively, in each plot. So, the total plots were 18 (varieties 2 × seedling age 3 × Replication 3).
Sampling and data collection procedure at different growth stages and harvest
Sampling was done at 15 days interval from 15 DAT up to 45 DAT for vegetative stages data and at harvest for yield and yield contributing data. At each sampling five random hills from each plot were uprooted avoiding border hills and washed them in running tap water. Then the plant samples were carried to the laboratory and necessary vegetative stages data were recorded. Yield and yield contributing data were recorded after harvest when 80–90% of the grains became golden in color and selected plants were cut at the ground level and were separately bundled and properly tagged for recording necessary data.
Data collection procedure at different growth stages
Plant height
The plant height was measured from the selected hills at 15 days interval from 15 DAT up to 45 DAT. The plant height was taken from the base of the plant (at soil level) up to the tip of the leaf. Plant height data was measured by a meter scale and converted into cm.
Number of leaves per plant
Number of leaves per plant was counted at 15 days interval from 15 DAT up to 45 DAT from the randomly selected plants of five hills of each plot where first simple leaf and the subsequent compound leaves were counted and converted in number of leaves per plant.
Number of tillers per hill
Number of tillers per hill was recorded from selected hills at 15, 30 and 45 DAT. Tillers which had at least one leaf visible were counted.
Dry weight of stem, leaf and root per hill
The plant parts such as leaves, stems and roots of five hills of each plot were detached and kept separately in oven at 82±20C for 72 hours. The oven dried samples were weighed for dry matter production.
Total dry matter
Total dry matter weight was measured by the sum of plant parts such as leaves, stems and roots.
Leaf area
Randomly collected six leaves per hill get five hills of each plot leaf area was measured by an automatic leaf area meter and manually through (length x breadth) of leaf blade. So, found adjustment factor from the ratio of leaf area meter and manual measurement of leaf blade. So, area of each leaf blade found through by the following formula–
Leaf area= K x L x W
Where: K= Adjustment factor (constant)
L= Length of leaf blade (cm)
W= Breadth of leaf blade (cm)
The value of K was 0.75 which was used for all stages of growth. Leaf area of each leaf was multiplied by the leaf number per hill to obtain total leaf area per hill at 15, 30 and 45 DAT.
Leaf area index (LAI)
Finally leaf area index (LAI) was calculated with the formula (Radford 1967; Hunt 1978) as follows-
Where, LA = leaf area (cm2), P = ground area (20 cm × 20 cm = 400 cm2 plant-1)