General experimental details: The experiment was conducted in 2004-05. A total of forty rice germplasm composed of 32 local aromatic, five exotic (V4, V27, V29, V37 and V38) and three nonaromatic (V8, V10 and V30) rice varieties as standard checks, were selected for this research (Table 1). Among the three nonaromatic varieties used, BR28 is a modern Boro, BR39 a modern T.Aman variety and the third one, Nizersail was used as a standard photoperiod sensitive genotype. Exotic genotypes were collected from Pakistan (Basmati PNR346), Nepal (Sarwati and Sugandha- 1) and Iran (Khazar and Neimat). The rest of the materials are representing their distribution throughout Bangladesh. Forty rice genotypes formed the treatment variables and were assigned randomly to each unit plot of 5 × 2 m dimension. Seedlings 930 days old) were transplanted in three sets of Aman season and 45 dayold seedlings in Boro season with a spacing of 20 × 20 cm. A fertilizer rate of 25–35–10–3 kg ha-1 of P–K–S–Zn in the form of triple super phosphate, muriate of potash, gypsum and zinc sulphate, respectively, was applied as basal dose at final land preparation. The nitrogen was top-dressed as urea in 2–3 splits to the contrary of a common dose with fixed time routine. The amount of urea and time of application were determined with the help of a leaf colour chart (Ladha, et al., 1998). A single hill was selected in each plot for plant height data. It was measured as a distance from ground level to the tip of the tallest panicle (Gomez, 1972). Environmental conditions: The four locations in different parts of Bangladesh were as follows: B = Benarpota Farm, BRRI Regional Station, Satkhira (22.72°N, 89.08°E). C = Charchandia Farm, BRRI Regional Station, Sonagazi, Feni (22.84°N, 91.39°E). D = Domar Seed Production Farm, BADC, Sonaroy, Domar, Nilphamari (26.10°N, 88.84°E). H = Headquarter Farm, Bangladesh Rice Research Institute, Gazipur (24.00°N, 90.42°E). Seed was sown in four dates, 3 in T.Aman (with an interval of 20 days) and 1 in Boro season: 1 = 1st planting in T. Aman (Sowing in seedbed on 16th July 2004), 2 = 2nd planting in T. Aman (Sowing in seedbed on 5th August 2004), 3 = 3rd planting in T. Aman (Sowing in seedbed on 25th August 2004), 4 = Planting in Boro season (Sowing in seedbed on 5th November 2004). The combination of locations × planting times resulted in 16 environmental conditions viz. B1, B2, B3, B4, C1, C2, C3, C4, D1, D2, D3, D4, H1, H2, H3 and H4. Statistical analysis: Stability analysis was done according to the regression model of Eberhart and Russel (1966).