The field experiment was conducted at the Field Laboratory of the Department of Agronomy, Patuakhali Science and Technology University, Patuakhali during the period of March to July 2012.
Design and layout of the experiment
The experiment was laid out in a randomized block design with two varieties, four treatments and three replications. So the total number of plots was 24. The area of a unit plot was (4 × 2.5) m2. Replication to replicationof the field and plot to plot distance was maintained as 1 m. & 50 cm .
Experimental treatments
The experiment included the following nitrogen treatments:
T1 = 175 kg ha-1 urea application at 15 days after transplanting (DAT)
T2 = 175 kg ha-1 urea application in two equal splits, 1/2 at 15 DAT +1/2 at 30 DAT
T3 = 175 kg ha-1 urea application in three equal splits, 1/3 at 15 DAT + 1/3 at 30 DAT at + 1/3 at 45 DAT
T4 = Guti urea (Urea Supergranules - USG) application @ 50 kg ha-1 at 10 DAT
Planting materials
BR-26National Seed Board authorized it in 1993 as an early variety for Aus season. It obtain an average 115 cm height at full maturity. Its strong stems prevent from lodging. Grains are long slender, white in color. Life of this variety spans about 115 days. It may give an yield of 4.00 ton ha-1 under proper management practice. BRRI dhan27 It was permitted as a variety by National Seed Board in 1994. It is also an early variety for and is suitable for cultivation as both direct seeded and transplanted in non-saline flood plain soil of Barisal and Patuakhali District. Average plant height of this variety is 140 cm. Though the plant height is higher, it can resist lodging. Leaf sheath at the base of the plants of this variety is somewhat violet in color. Grain is fatty and contains protein about 7.8%. It takes about 115 days to complete its life cycle. BRRI dhan27 can give a yield of 4.0 t ha-1 under proper management practice.
Sampling and processing of the data
During weeding of different plots on different date weeds samples were collected to record the data on weed related parameter. Ten hills from each plot were randomly selected, uprooted and properly tagged before harvesting for recording the necessary data on crop characters. The crop of each plot was harvested at full maturity when 80% of the grains turned in golden yellow color.
Data collection
Data was collected on different weed properties and crop and yield contributing characters as following:
At 30 Days after transplanting-
- Plant height (cm)
- Number of tillers per hill
At maturity-
- Plant height (cm)
- Total number of tillers
- Effective tillers
- Non-effective tillers
- Panicle length (cm)
- Filled grains panicle-1
- Sterile spikelet panicle-1
- Thousand grain weight
- Grain yield
- Straw yield
- Biological yield
- Harvest index
Procedure of data collection
Data was collected on fourteen parameters of the experiment. A brief outline of data collection procedure is given below.
Plant height: Plant height was measured in cm from the ground level to the tip of the longest panicle.
Total tillers hill-1: Tillers which had at least one leaf visible were counted. It included both effective and non-effective tillers.
Effective tillers hill-1: The panicle which had at least one grain was considered as effective tiller.
Non-effective tillers hill-1: The panicle which had no grain was considered as non-effective tiller.
Panicle length: Panicle length (cm) was recorded from the neck-node to the tip of each panicle.
Filled grains panicle-1: Presence of any food material in the spikelet was considered as grain. Total number of grains of ten randomly selected panicle was counted. Average mean of filled grains of these ten panicles was taken as number of filled grains panicle-1.
Unfilled grains panicle-1: Grains lacking any food material inside the grain was considered as sterile spikelet and such grains present on the each panicle were counted.
Thousand grain weight: One thousand clean dried grains were counted from the seed stock obtained from the ten sample plants of each plot and their weight (g) was taken in by using an electric balance.
Grain yield: Grains obtained from each unit plot were sun dried and weighed carefully. The dry weights of grains from the plants of the ten sample hills were added to the respective plot yield to record the final grain yield of each plot. The grain yield was eventually converted to t ha-1.
Straw yield: Straw obtained from each unit plot including the straw of ten sample hills of respective unit plot was dried in the sun and weighed to record the straw yield of each plot and finally converted to t ha-1.
Biological yield: Biological yield (g) was measured by adding grain and straw yield and recorded.
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).
Harvest index (%) =
x 100