The experiment was conducted at the Agronomy field of Sher-e-Bangla Agricultural University, Dhaka, Bangladesh during June to November, 2008. Geographically, the experimental area is located at 23077' N latitude and 90033' E longitude at the elevation of above 18 m of the sea level. The soil of the experimental field belongs to the Shallow Red Brown Terrace Soils. The experiment was carried out with 10 different treatments were as follows:
T1 = Control,T2 = Green manure @ 15 t ha-1,T3 = Green manure @ 15 t ha-1 + N40 P6 K36 S10 (50% NPK) ,T4 = Poultry manure @ 4 t ha-1,T5 = Poultry manure @ 4 t ha-1 + N40 P6 K36 S10 (50% NPK), T6 = Cowdung @ 12 t ha -1, T7 = Cowdung @ 12 t ha-1 + N40 P6 K36 S10 (50% NPK) ,T8 = Vermicompost @ 8 t ha-1,T9 = Vermicompost @ 8 t ha-1 + N40 P6 K36 S10 (50% NPK), T10 = N80 P12 K72 S10 (100% NPK) The experiment was laid out in a randomized completely block design (RCBD) with 3 replications. The unit plot size was 12 m2 . The experiment was laid out a randomized completely block design with 3 replications. The unit plot sizw was 12 m2
The experiment was carried out with rice variety ‘BRRI dhan40’. A common pocedure was followed in raising of seedlings in seed bed. Seedlings of 25 days old were uprooted from the nursery beds carefully. Seedlings were transplanted according to the treatments in the well-puddled experimental plots. Spacings were given as 20 cm ×15 cm. Organic manures were applied before land preparation as per treatments. Thirty-days-old Sesbania rostrata green plants were incorporated as green manure. Others manures were used as decomposed. Chemical fertilizers were applied as per treatments during final land preparation. Urea, triple superphosphate, muriate of potash and gypsum were applied as sources of N, P, K and S. In case of N one-third urea was applied as basal dose at the time of final land preparation and incorporated well into the soil. Rest two-third of urea was applied in two equal splits at 30 and 60 days after transplanting (DAT). All intercultural operations were done carefully. The first weeding was done at 15 days after transplanting (DAT) followed by second and third weeding was done at 15 days interval after first and second weeding. Irrigation was applied by alternate wetting and drying from transplanting to maximum tillering stage. From panicle initiation (PI) to hard dough stage, a thin layer of water (2-3 cm) was kept on the plots. Water was removed from the plots during ripening stage. The crop of each plot was harvested separately on different dates when 90% of the grains become golden yellow in colour.
The first plant height was measured at 30 DAT and continued up to harvesting period with 20 days interval. Plant height was determined by measuring the distance from the soil surface to the tip of the leaf before heading and to the tip of the flag leaf after heading. The collected data were finally averaged. Number of tillers hill -1 was counted at 20 days interval starting from 30 DAT and continued up to harvest from 10 pre-selected hills and finally averaged them to have tiller number hill-1. Ten hills from each plot were uprooted and oven dried at 85 ± 50C for 72 hours from which the dry matter weight was recorded at 20 days interval up to 90 days. The dry matter accumulation of the crop per unit land area in unit of time is referred to crop growth rate (CGR), expressed as g m-2 d-1. The mean CGR values for the crop during the sampling intervals were computed using the formula of Brown, (1984).
CGR= [W2-W1/SA(t2-t1)] gm-2 d-1
Where, SA= Ground area occupied by the plant at each sampling. W1 and W2 are the total dry matter production in grams at the time t1 and t2 , respectively. The relative growth rate at which a plant incorporates new material into its sink is measured by Relative Growth Rate of dry matter accumulation and is expressed in g g-1d-1. Relative growth rate was worked out by following the formula of Radford (1967).
RGR= (LnW2-LnW1/T2-T1) gg-1d-1
Where, W1 and W2 is initial and final dry matter weight at the time T1 and T2, respectively. Ln refers to Natural Logarithm. The grain weights for each plot were recorded after proper sun drying and then converted into t ha-1. The grain yield was adjusted at 12% moisture level.
The data was analyzed using CoStat software programme. The mean differences among the treatments were compared by multiple comparison tests using Duncan’s Multiple Range Test. Regression analysis was done by using SPSS software package.