Blossoming Characteristics in Black Cumin Genotypes in Relation Seed Yield Influenced by Sowing Time ()
1. Introduction
Black cumin (Nigella sativa L.; Family-Ranunculaceae) is an important annual herbaceous plant. Spice crop is cultivated in widely cultivated throughout South Europe, Syria, Egypt, Saudi Arabia, Iran, Pakistan, India and Turkey [1] -[3] . For successful production of any crop, appropriate planting time is very important. Especially for seed production, sowing time is very sensitive for quality seed production. Planting controls the phonological development which influences seed production [4] . Shortening of the growing cycle decreases the amount of radiation intercepted during the growing season and thus total dry weight of plant [5] [6] . With delayed sowing, development is accelerated because the crops encounter higher temperatures during the vegetative growth [7] and decreases seed weight and the number of umbrella per plant [4] [8] . Because of occurrence lack of suddenly winter chilling, delayed sowing date is better [8] [9] . Early sowing has been favorable for disease, and leads to early flowering, resulting poor quality of seed [4] . Optimum temperature for germination is 16.19˚C to 22.14˚C [10] , so black cumin is plenty during winter season in Bangladesh. To realize the full yield potential characteristics of black cumin, agricultural practices will have to be optimized for its production. Optimum sowing time of black cumin in Bangladesh has rarely investigated. This study aims 1) to assess the effect of various sowing time on flowering for seed production of black cumin genotypes, and 2) to determine the interaction effect of sowing time and genotypes.
2. Materials and Methods
The study was conducted at the Horticulture Research Field, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur during the winter season of 2011-12. The experiment having two factors was laid out in a randomized complete block design with three replications. The treatments were randomly allotted in each block. Each block consisted of 16 plots and the dimension of each plot was 1.2 m ´ 1.2 m (1.44 m2) having a plot to plot and block to block distances of 0.5 m and 1.0 m, respectively. Soil of the experimental field was silty clay loam and soil PH 5, 84. The experiment plots were manured and fertilized with Cowdung, Urea, TSP and MP at the rate of 10 t, 125, 95 and 75 kg/ha respectively [11] . The seeds were mixed with some loose soil to allow uniform sowing in rows. Then, seeds were sown in rows 15 cm apart continuously by hand @ 10 kg/ha [11] , maintaining a depth of one cm. Continuous line sowing was done to maintain plant to plant distance 10 cm by thinning later on [11] . The seeds were covered with loose soil properly just after sowing and gently pressed by hands. The crop was harvested when 50% of the capsules changed color from green to straw color.The experiment was two factorials. Factor A: 4 genotypes were V1: Exotic, Iran; V2: BARI kalozira-1; V3: Local, Faridpur and V4: Local, Natore. Factor B: Sowing date: D1: 16 October; D2: 1 November; D3: 16 November and D4: 1 December. Therefore, treatment combinations were 16 in total. So, in 3 replications total plot was 48. Data were collected from the inner rows of each plot to avoid the border effect. In each unit plot, 10 plants were selected randomly for recording data. The following seed yield and yield contributing characters were recorded. Days to 1st emergence: Number of days required for first emergence after seed sowing was calculated from all the plots separately by close observation after seed sowing. Days to 50% emergence: Number of days required for 50% emergence after seed sowing was calculated from all the plots separately by close observation after seed sowing. Days to 1st flower bud initiation: Days to 1st flower bud initiation was recorded by calculating the days from the date of sowing to bud initiation by observing the plants every morning. Days to flower bud initiation in 50% plants: Days to 50% flower bud initiation was recorded by calculating the days from the date of sowing to bud initiation by observing the plants every morning. Days to 1st flower blooming: Days to 1st flower blooming was recorded by calculating the days from the date of sowing to bud initiation by observing the plants every morning (1st opened flower in plot). Days to flower blooming in 50% plants: Days to flower in 50% plant was recorded by counting the days from the date of sowing to flower in 50% plants every morning (50% of the plant in a plot opened flower).Days to 1st capsule setting: Days to 1st capsule setting was recorded by counting the days from the date of sowing every morning. Days to capsule setting in 50% plants: Days to capsule setting in 50% plants was recorded by counting the days from the date of sowing every morning. Days to first capsule ripening: Days to 1st capsule ripening in each plot was recorded by counting the days from the date of sowing every morning. When capsule colour was changed from green to straw, then it was counted as ripened. Days to capsule ripening in 50% plants: Days to capsule ripening in 50% plants in each plot was recorded by counting the days from the date of sowing every morning. When capsule colour was changed from green to straw, then it was counted as ripened. This parameter indicates whether the genotypes was short-durated or late. The collected data were analyzed statistically using MSTAT-C computer package (Michigan State University, East Lansing, MI, USA) following the methods of [12] . The analysis of variance procedure (ANOVA), differences among treatment means were determined using the Least Significant Difference (LSD) at 5% level of significance
3. Results and Discussion
3.1. Results
The present investigation initiated to study the effect of planting time on the blossoming characters in black cumin genotypes. The results obtained are presented in tables and figures and discussed character wise under the following heads:
3.1. 1. Days to 1st Emergence
Variation among the genotypes was observed and the days to 1st emergence ranged from 7.42 to 8.58 days (Table 1). The V3 genotype took the highest days (8.58 days) to 1st emergence, which had no significance difference with genotype V2 (8.50 days) and V4 (8.42 days). The earliest emergence was recorded in the V1 genotype (7.42 days), which was statistically different to all. D1 and D2 took 7.67 and 7.83 days which was statistically similar. D3 (8.75 days) and D4 (8.67 days) were also statistically similar. In combined effect, statistically higher days were obtained from V2, V3 and V4 with D3 and D4 which was 9 days. The lowest days 7 were showed from V1D1 and V1D2.
3.1. 2. Days to 50% Emergence
Evident of significant different days required for 50% emergence were observed in main effect of genotypes, ranging from 9.83 days (V1) to 11.83 days (V4) (Table 1). V3 (11.75 days) was statistically similar to V4. V2 (10.75 days) showed moderate required days. Requiring the lowest days showed higher vigor of V1. Variation also observed in date of planting. D1 and D2 each took 10.25 days, D3 and D4 each took 11.83 days. In combined effect, statistically higher 12.67 days required for V3D4, V4D3 and V4D4. The lowest 9 days was observed in V1D1 and V2D2. In interaction days to 50% emergence ranged from 9.00 to 12.67 days. Lowest days required was observed in V1S2. All combination of spacing with V3 and V4 showed statistically similar as well as highest days required.
3.1.3. Days to 1st Flower Bud Initiation
There was clear significant different among genotypes in 1st flower bud initiation (Table 1). It was the highest (51.83 days) in V1, followed by V3 (49.08 days). V2 (47.92 days) and V4 (45.42 days) were significantly different from each other. It may be controlled genetically. In case of sowing date, early sowing took higher as well as late sowing took lower time. D1, D2, D3 and D4 took 56.92, 47.42, 46.08 and 43.83 days simultaneously, which each was significantly different from each other. In interaction, V3D1 took the highest days (59.00 days) to 1st flower bud initiation, where the lowest 39.33 days was obtained from V4D4.
3.1.4. Days to Flower Bud Initiation in 50% Plants
Days to 50% flower bud initiation significantly varied among genotypes (Table 1). It was the highest in V1 (60.00 days) and the lowest 54.67 days in V2. V2 was statistically similar to V4 (54.92 days). V3 (56.00 days) required statistically moderate days. On the other hand, early sowing D1 took the highest (65.58 days) and late sowing D4 took the lowest (50.75 days). D2 and D3 took 56.42 and 52.83 days. Each date was statistically different from each other. In interaction, V1D1 needed the highest (66.33 days) and V4D4 needed the lowest (48.33 days).
3.1.5. Days to 1st Flower Blooming
Significant variation was observed in V1 with other genotype in days to 1st flower blooming (Table 1). V1 took maximum days (61.75 days) which was statistically different from V2 (60.33 days), V3 (59.75 days) and V4 (59.33 days). V2, V3 and V4 were statistically similar. A clear different was found in various date of sowing. Maximum (70.67 days) was observed in D1, where minimum (53.17 days) from D4. D2 (61.17 days) and D3 (56.17 days) showed moderate time. Each sowing date was significantly different from each other. In interaction between genotypes and date of sowing, V4D1 took the highest (71.33 days) and V4D4 (51.67 days) took the lowest time for 1st flower blooming.
Table 1. Days to emergence and flowering characteristics in black cumin genotypes as influenced by sowing time.
Means followed by the same letter(s) in a column are not significantly different. Variety: Exotic (V1); BARI kalozira-1 (V2); Faridpur local (V3); Natore local (V4). Date of sowing: 16 Oct, 2011(D1); 1Nov, 2011 (D2); 16 Nov, 2011 (D3); 1 Dec, 2011 (D4).
3.1.6. Days to Flower Blooming in 50% Plants
There was significant variation in V1 with other genotype in days to 50% flower blooming (Table 1). V1 take maximum days (68.17 days) which were statistically different from V2 (65.25 days), V3 (64.75 days) and V4 (64.83 days). V2, V3 and V4 were statistically similar. A clear different was found in various date of sowing. Maximum (76.08) days was observed in D1, where minimum (59.00 days) from D4. D2 (61.17 days) and D3 (61.75 days) showed moderate time. Each sowing date was significantly different. In interaction between genotypes and date of sowing, V1D1 took the highest (77.00 days) and V4D4 (58.33 days) took the lowest time for 50% flower blooming.
3.1.7. Days to 1st Capsule Setting
Variation in days to 1st capsule setting was observed in genotypes (Table 2). V1 obtained 81.83 days which was maximum and statistically different from other genotype, where V2 took 75.08 days which was minimum. V3 take 78.83 days followed by V4 (76.42 days). Each genotype was statistically different. On the other hand, sowing date D1 obtained 87.42 days to 1st capsule setting, followed by D2 78.83 days. D3 took 74.33 days which was statistically different from the minimum days (71.58) obtained by D4. In interaction, V1D1 showed 90.33 days
Table 2. Days to fruiting and maturation characteristics in black cumin genotypes as influenced by sowing time.
Means followed by the same letter(s) in a column are not significantly different. Variety: Exotic (V1); BARI kalozira-1 (V2); Faridpur local (V3); Natore local (V4). Date of sowing: 16 Oct, 2011(D1); 1Nov, 2011 (D2); 16 Nov, 2011 (D3); 1 Dec, 2011(D4).
which was maximum, where V2D4 took minimum (67.67 days).
3.1.8. Days to Capsule Setting in 50% Plants
Days to 50% capsule setting was statistically varied in genotypes (Table 2) ranging from 94.58 days (V4) to 98.58 days (V1). V2 (94.33 days) was statistically different from V1 and V3 (96.50 days), but similar with V4. Days to 50% capsule setting clearly distinguished by spacing. It increased with increasing spacing, ranged from 88.58 days (D4) to 105.42 days (D1). D3 showed 94.83 days and D3 95.17 days, which each was statistically similar. In combination effect, it ranged from 86.00 days (V1D1) to 110.33 days (V1D1). Gradually less time required from D1 to D4 with interaction with all genotypes.
3.1.9. Days to 1st Capsule Ripening
In days to first capsule ripening, V1 (114.33 days) was statistically different from V2 (110.92 days), V3 (111.17 days) and V4 (110.50 days). V2, V3 and V4 were statistically similar (Table 2). In date of sowing, the highest days (124.83 days) were obtained by D1, as well as lowest (100.67 days) by D4. D2 and D3 take 113.08 and 108.33 days simultaneously. Each date was significantly different. In combined effect, V1D1 took maximum time (128.00 days), where minimum (103.67 days) obtained from V4D4.
3.1.10. Days to Capsule Ripening in 50% Plants
There was significant different in days to first capsule ripening (Table 2). V1 (121.33 days) was statistically different from V2 (118.42 days), V3 (118.50 days) and V4 (118.58 days). V2, V3 and V4 were statistically similar. In date of sowing, highest days (132.92) were obtained by D1, as well as the lowest (106.92 days) by D4. D2 and D3 take 121.58 and 115.42 days simultaneously. Each date was significantly different. In combined effect, V1D1 took maximum time (134.33 days), where minimum (109.33 days) obtained from V4D4. The finding was nearly supported by BARI (2007) describing 135 to 145 days for ripening.
3.1.11. Plant Height (cm)
Genotypes were significantly different in plant height (Table 3). Maximum height 51.83 cm was obtained from V1 and minimum 44.13 cm from V4. V2 (46.81 cm) and V3 (46.46 cm) was statistically similar. Date of sowing was also significantly different from each other. Maximum height was found in D2 (50.78 cm), and minimum (44.15 cm) from D4. D1 and D3 showed 48.31 and 45.98 cm simultaneously. In combined effect of genotype and date of sowing, V1D2 showed 55.83 cm which was maximum, and minimum (41.20 cm) from interaction of V4 and D4.
3.1.12. Number of Primary Branches per Plant
Primary branches per plant are an important yield contributing character (Table 3). It was the highest 4.73 in V4, which was statistically similar to V1 (4.63). Also V1 and V2 (4.53) was statistically similar. Significantly the lowest primary branch 4.30 was obtained from V3. In case of V2, date of sowing was statistically different from each other. D1 (4.81) and D2 (4.82) was statistically similar, followed by D3 (4.35). D4 obtained 4.20 which were the lowest among dates. In interaction number of primary branch 5.00 was the highest in V1D1, as well as the lowest (4.00) in V3D4.
3.1.13. Number of Secondary Branches per Plant
It was the highest in V1 (8.89), followed by V2 (8.68) (Table 3). V4 obtained 8.07 which was statistically different from V3 (7.83), the lowest number of secondary branch. In case of date of sowing, D1 (9.68) and D2 (9.81) was statistically similar, followed by D3 (7.27). D4 obtained the lowest number of secondary branch (6.70) which was statistically different from D3. In interaction, V1D2 (10.73) gave the highest number of secondary branch, and V3D4 (6.10) showed the lowest.
3.1.14. Number of Tertiary Branches per Plant
The number of tertiary branch was the highest in V1 (20.23), followed by V2 (17.48) (Table 3). V4 obtained 16.43 which were statistically different from the lowest number of tertiary branch (15.62) which obtained from V3. In case of date of sowing, D1 (19.46) and D2 (19.82) was statistically different, followed by D3 (15.78). D4 obtained the lowest number of tertiary branch (14.69) which was statistically different from D3. In interaction,
Table 3. Plant height and branching characteristics in black cumin genotypes as influenced by sowing time.
Means followed by the same letter(s) in a column are not significantly different. Variety: Exotic (V1); BARI kalozira-1 (V2); Faridpur local (V3); Natore local (V4). Date of sowing: 16 Oct, 2011(D1); 1 Nov, 2011 (D2); 16 Nov, 2011 (D3); 1 Dec, 2011(D4).
V1D2 (22.00) gave the highest number of tertiary branch, and V3D4 (13.00) showed the lowest.
3.1.15. Length of Leaf (cm)
There was no significant different among genotypes in leaf, ranged from 3.03 cm (V4) to 3.05 cm (V1) (Table 4). V2 and V3 showed 3.04 and 3.06 cm simultaneously. In case of date of sowing, it was the highest in D2 (3.27 cm) which was statistically similar to D1 (3.23 cm), followed by D3 (2.93 cm). D4 showed the statistically the lowest leaf length (2.75 cm). In interaction, it was the highest (3.27 cm) in V1D2 and the lowest (2.67 cm) in V4D4.
Table 4. Leaf, capsule and pedicle characteristics in black cumin genotypes as influenced by sowing time.
Means followed by the same letter(s) in a column are not significantly different. Variety: Exotic (V1); BARI kalozira-1 (V2); Faridpur local (V3); Natore local (V4). Date of sowing: 16 Oct, 2011 (D1); 1 Nov, 2011 (D2); 16 Nov, 2011 (D3); 1 Dec, 2011 (D4).
3.1.16. Breath of Leaf (cm)
In breath of leaf, Genotype V1 (2.57 cm) was significantly different (Table 4) from V2 (2.24 cm), V3 (2.32 cm) and V4 (2.28 cm). There was no significant different among V2, V3 and V4. In case of date of sowing, D1 (2.58 cm) and D2 (2.59 cm) was statistically similar, followed by D3 (2.19 cm). D4 (2.05 cm) obtained the significantly the lowest leaf breath. In combined effect, the highest leaf breath (2.73 cm) was obtained from interaction of V1 with D1 and D2, and the lowest leaf breath (2.00 cm) was found in V4D4.
3.1.17. Length of Capsule (cm)
Genotypes were significantly different from each other in capsule length (Table 4), where the highest obtained from V1 (1.17 cm), and the lowest (1.00 cm) from V3. Second highest capsule, length was observed in V2 (1.10 cm), followed by V4 (1.02 cm). Date of sowing also effect significantly in capsule length, where maximum was in D2 (1.12 cm), followed by D1 (1.09 cm). 1.05 and 1.03 cm capsule length were found in D3 and D4 simultaneously, which was statistically different. In interaction, V1D2 (1.21 cm) gave the highest and V4D4 (0.95 cm) gave the lowest capsule length.
3.1.18. Capsule Diameter (cm)
There was significant different among genotypes in capsule diameter (Table 4). It was maximum (0.82 cm) in V1, followed by V3 (0.77 cm), which was statistically different. V2 (0.75 cm) and V4 (0.74 cm) showed no significant different. Capsule diameter also varied in various sowing date. D2 (0.80 cm) showed the highest followed by D1 (0.78 cm). No significant different was observed in D3 (0.75 cm) and D4 (0.74 cm). In combined effect of genotype and date of sowing, capsule diameter was highest (0.85 cm) in V1D2 and lowest (0.71 cm) in V4D4.
3.1.19. Length of Pedicle (cm)
Genotypes showed significant different in pedicle length (Table 4). Genotype V1 (7.81 cm) gave maximum pedicle length, where minimum was observed in V3 (5.54 cm). No significant different was found in V2 (5.55 cm) and V3. V4 (5.81 cm) showed moderate pedicle length. Pedicle length was also effected significantly by various date of sowing. D2 (6.83 cm) showed maximum pedicle length, where D4 (5.71 cm) showed the minimum. D1 (6.26 cm) and D3 (5.92 cm) showed moderate pedicle length. Each date of sowing was significantly different from each other. In combined effect, V1D2 showed (8.53 cm) highest and V3D4 (4.93 cm) showed the lowest pedicle length.
3.1.20. Fresh Weight per Plant (g)
It indicates plant size and vigor (Table 5). There was significant different among genotypes in fresh weight per plant (Table 5) which varied from 9.39g (V4) to 13.87g (V1). V2 showed 10.11g and V3 9.76g. Each genotype was significantly different from each other. Shah (2011), in India reported less fresh weight per plant 3.36 ± 0.27g. Date of sowing was also effect on fresh weight per plant. D1 (12.95 g) gave the highest and D4 (9.47 g) the lowest. D2 and D3 gave moderate fresh weight per plant which was 10.83 and 9.88g. Each date of sowing was statistically different from one another. In interaction, maximum fresh weight was obtained from V1D1 (16.15 g) and minimum from V4D4 (8.40 g).
3.1.21. Number of Seeds per Capsule
Different was found among genotypes in number of seed per capsule (Table 5). V1 (95.77) and V4 (95.51) showed higher and significantly similar number of seed per capsule. V2 (93.53) and V3 (89.58) were significantly similar. In date of sowing, D4 (98.24) was higher followed by D1 and D2 which each was 95.35. D3 (89.58) was significantly lower in number of seed per capsule. In combined effect of genotypes and date of sowing, maximum number of seed per capsule was obtained from V1D4 (100.67) and minimum from V3D3 (88.73).
3.1.22. Number of Capsule per Plant
Among yield contributing characters, number of capsule per plant is one of the most important. There was significant different among species in number of capsule per plant (Table 5), which was maximum 20.28 in V1 and minimum 16.61 in V4. V2 (17.38) and V3 (17.22) was statistically similar. On the other hand, date of sowing also effect on capsule per plant. It was maximum in D2 (22.06) followed by D1 (21.55), D3 (14.88) and D4 (12.99). In combined effect, the highest 24.17 was obtained from V1D2, and the lowest (12.17) from V4D4.
3.1.23. Fresh Seed Weight per Capsule (g)
There was no significant different among genotypes in fresh seed weight per capsule (Table 5). Maximum weight (0.21 g) was obtained from V1. V2, V3 and V4 gave same fresh seed weight which was 0.20 g. But in case of sowing date D1 (0.21 g), D2 (0.22 g) and D3 (0.21 g) was statistically similar and was different from D4 (0.17 g). In interaction, maximum weight was 0.22 g which was found in V1 combination with D2 and D3. Minimum
Table 5. Plant weight and capsule characteristics contributing to yield in black cumin genotypes as influenced by sowing time.
Means followed by the same letter(s) in a column are not significantly different. Variety: Exotic (V1); BARI kalozira-1 (V2); Faridpur local (V3); Natore local (V4). Date of sowing: 16 Oct, 2011 (D1); 1 Nov, 2011 (D2); 16 Nov, 2011 (D3); 1 Dec, 2011 (D4).
0.16 g was obtained from V4D4.
3.1.24. Fresh Seed Yield per Plant (g)
Genotypes were statistically different from each other in fresh seed yield per plant (Table 5). Maximum yield was observed in V1 (4.27 g) and minimum in V4 (3.30 g). V2 and V3 were moderate as 3.55 and 3.52 g simultaneously. Date of sowing also effect significantly in fresh seed yield per plant. Maximum yield was obtained in D2 (4.77 g), followed by D1 (4.58 g), which was statistically different. D3 (3.10 g) was moderate and D4 (2.19 g) was minimum which was statistically different. In interaction, maximum yield was obtained from V1D2 (5.40 g) and minimum from V4D4 (1.95 g).
3.1.25. Dry Weight per Plant (g)
There was significant different among all genotypes in dry weight per plant (Table 6). It was maximum in V1 (9.01 g), and minimum in V4 (6.10 g). V2 (6.58 g) and V3 (6.34 g) showed moderate dry weight per plant. Date of sowing was also significantly different from each other in dry weight per plant. D1 (8.42 g) was maximum and D4 (6.16 g) was minimum, where D2 (7.04 g) and D3 (6.42 g) were moderate. In combined effect, maximum dry weight per plant was observed in V1D1 (10.50 g) and minimum 5.46 g in V4D4.
Table 6. Yielding characteristics in black cumin genotypes as influenced by sowing time.
Means followed by the same letter(s) in a column are not significantly different. Variety: Exotic (V1); BARI kalozira-1 (V2); Faridpur local (V3); Natore local (V4). Date of sowing: 16 Oct, 2011 (D1); 1 Nov, 2011 (D2); 16 Nov, 2011 (D3); 1 Dec, 2011 (D4).
3.1.26. Dry Seed Weight per Capsule (g)
There was no significant different among genotypes in dry seed weight per capsule (Table 6). It was the highest in V1 (0.18 g), followed by V2, V3 and V4 which each was 0.17 g. Date of sowing significantly effect on dry seed weight per capsule. It was maximum in D2 (0.19 g) which was statistically similar to D1 (0.18 g). D1 also was statistically similar to D3 (0.18 g), but different from D4 (0.14 g). A variation was observed in interaction. Maximum dry weight was found in V2D1 (0.19 g) and minimum 0.13 g in V2D4.
3.1.27. 1000 Seed Weight (g)
1000 seed weight is an important yield contributing character. It was maximum in V1 (2.40 g) which was statistically similar to V2 (2.34 g) and V3 (2.38 g) (Table 6). V2 and V3 were also statistically similar to V4 (2.27 g). In case of date of sowing, D1 (2.46 g), D2 (2.51 g) and D3 (2.55 g) was statistically similar. D4 (1.88 g) was statistically different from D1, D2 and D3. In combined effect of genotypes and date of sowing maximum 1000 seed weight 2.69 g was obtained from the interaction of V1 and D3, where minimum 1.79 g in V4D4.
3.1.28. Dry Seed Yield per Plant (g)
Yield of per plant contribute directly in total yield. Genotype each was significantly different from each other in dry seed yield per plant. Maximum yield was found in V1 (3.59 g), followed by V2 (2.98 g) (Figure 1(a)). V3 (2.95 g) showed moderate and V4 (2.77 g) was minimum in yield per plant. In case of date of sowing (Figure 1(b)), it was the highest in D2 (4.00 g) which was statistically different from D1 (3.85 g). Also D3 (2.60 g) and minimum D4 (1.84 g) was statistically different. In combined effect (Figure 2), maximum (4.54 g) yield was found in V1D2 and minimum (1.64 g) in V4D4.
3.1.29. Stover Yield (t/ha)
There was significant different among genotypes in stover yield (Table 6). Significantly maximum stover yield was found in V4 (4.66 t/ha) and minimum in V3 (3.15 t/ha). V1 (4.48 t/ha) and V2 (3.26 t/ha) was statistically different, where V2 and V3 was statistically similar. On the other hand, date of sowing clearly effect on stover
(a) (b)
Figure 1. Seed yield per plant of black cumin as influenced by genotype (a) and date of sowing (b).
Figure 2. Seed yield per plant of black cumin as influenced by interaction of genotype and date of sowing. Vertical bars represent standard error of treatment means. Means followed by the same letter(s) in a column are not significantly different. Variety: Exotic (V1); BARI kalozira-1 (V2); Faridpur local (V3); Natore local (V4). Date of sowing: 16 Oct, 2011 (D1); 1 Nov, 2011 (D2); 16 Nov, 2011 (D3); 1 Dec, 2011 (D4).
yield. Early sowing gave higher stover yield. It gradually decreased in late sowing. D1 (4.69 t/ha), D2 (3.89 t/ha), D3 (3.56 t/ha) and D4 (3.42 t/ha) was statistically different from each other. In combination of genotype and date of sowing, the highest stover yield was obtained from V4D1 (5.76 t/ha), and the lowest (2.83 t/ha) from V3D4. In every genotype, gradually late sowing gave gradually lower stover yield.
3.1.30. Harvest Index (%)
It is the indicator of efficient use of nutrients (Table 6). Each genotype was statistically different from each other in harvest index, where it was the highest in V3 (62.00%), and the lowest (39.06%) in V4. V1 (52.39%) and V2 (58.86%) showed moderate harvest index. Date of sowing also effect on harvest index. D2 (70.23%) showed maximum harvest index, followed by D1 (56.00%). D3 (49.76%) showed moderate and D4 (36.33%) showed minimum harvest index. In interaction, V3D2 (84.33%) showed maximum and V4D4 (25.96%) showed the minimum.
3.1.31. Seed Yield (t/ha)
Seed yield per hectare is the ultimate goal. It was significantly the highest 2.37 t/ha in V1, followed by V2 (1.96 t/ha) (Figure 3(a)). V2 and V3 (1.97 t/ha) were statistically similar. The lowest yield was found in V4 (1.84 t/ha). In some places of Bangladesh, seed yield observed up to 1.5 t/ha (www.stoppressbd.com/news_details/638). In case of date of sowing, it effect significantly in yield. Maximum yield was obtained from D2 (2.65 t/ha), where minimum in D4 (1.22 t/ha). D1 (2.55 t/ha) and D3 (1.73 t/ha) was statistically different (Figure 3(b)). In combined effect, maximum yield 3.00 t/ha was obtained in V1D2 and minimum 1.08 t/ha in V2D4 and V4D4 (Figure 4).
3.1.32. Correlation among Characters
Correlation co-efficient values and level of significance among 10 yields, yield attributing and other characters influenced by genotypes spacing are presented in Table 7. There was moderate and strong positive correlation
(a) (b)
Figure 3. Seed yield ha-1 of black cumin as influenced by genotype (a) and date of sowing (b).
Figure 4. Seed yield ha-1 of black cumin as influenced by interaction of genotype and date of sowing. Vertical bars represent standard error of treatment means Means followed by the same letter(s) in a column are not significantly different. Variety: Exotic (V1); BARI kalozira-1 (V2); Faridpur local (V3); Natore local (V4). Date of sowing: 16 Oct, 2011 (D1); 1 Nov, 2011 (D2); 16 Nov, 2011 (D3); 1 Dec, 2011 (D4).
Table 7. Correlation coefficients among seed yield, yield determinants, plant height and number of branches in black cumin as influenced by genotypes and time of sowing.
*Correlation is significant at the 5% level. **Correlation is significant at the 1% level, SY = Seed yield (t/ha); PH = Plant height (cm); NPB = Number of primary branches per plant; NSB = Number of secondary branches per plant; NTB = Number of tertiary branches per plant; PL = Pedicle length (cm); SPC = Seed per capsule; CPP = Capsule per plant; TSW = Thousand seed weight (g); STY = Stover yield (t/ha); HI = Harvest index (%).
except seed per capsule. Relation with plant height at harvest (0.82**), Number of primary branch per plant (0.57*), number of secondary branch per plant (0.90**), number of tertiary branch per plant (0.87**), pedicle length (0.58*), seed per capsule (0.02), capsule per plant (0.97**), 1000 seed weight (0.67**), stover yield (0.43) and harvest index (0.74**). Plant height also had shown mostly positive strong and moderate correlation with character except seed per capsule (0.05). Number of primary, secondary and tertiary branch per plant showed strong positive correlation with almost characters but positive and week with seed per capsule. Pedicle length showed strong positive correlation with most characters but week seed per capsule (0.21), 1000 seed weight (0.30) and harvest index (0.23). Seed per capsule showed almost weak and sometime negative (1000 seed weight and harvest index). Capsule per plant exhibited mostly moderate positive correlation except seed per capsule. 1000 seed weight had moderate to week positive correlation with all characters. Stover yield (t/ha) exhibited moderate to week but positive correlation with all characters except harvest index (−0.21). Harvest index showed moderate to week positive correlation with most character, except seed per capsule (−0.28) and stover yield (−0.21).
3.2. Discussion
The minimum period required to 1st emergence may be due to high vigor of seed, and maximum period due to low vigor. Variation also observed in date of planting. Early sowing took significantly lower, and late sowing higher days, may be due to early sowing get upper temperature than late sowing which influenced 1st emergence (Figure 5) and than late sowing which influenced 50% emergence. Bud initiation, days to 1st flower blooming and days to 50% flower blooming are influence by environment. Combination effect might be depended on genetical as well as environment. For flowering, a certain cool and humid weather was needed. Variation in days to 1st capsule setting was observed in genotypes. Days to 50% capsule setting was statistically varied in genotypes. and gradually less time required from D1 to D4 with interaction with all genotypes. In days to first capsule ripening in early sowing, the highest days were obtained by D1, as well as lowest D4. D2 and D3 take simultaneously. In combined effect, V1D1 took maximum time (134.33 days), where minimum (109.33 days) obtained from V4D4. The finding was nearly supported by [11] describing 135 to 145 days for ripening. It might be due to comparatively high temperature and humid weather. Plant height is an important factor. Genotypes were significantly different in plant height. This result of plant height was in partial conformity in case of V2 with the findings of [11] , where it was reported that height laid between 55 to 60 cm. The result also partially similar to finding of Shah et al., (2006) [13] who found height 41.12 to 46.51 cm. [14] ) Valadabadi and Aliabadi (2011) found plant height 58 to 82 cm [15] . Tuncturk et al., (2005) found plant height 34.68 to 40.68 cm. But [16] Toncer and
Figure 5. Meteriological parameters of the experimental period (2011-12). Source: Weather Station, BSMRAU, Gazipur-1706.
Kizil (2004) found an upper range 64.9 to 71.5 cm, and [17] Rahnavard et al., (2010) observed a lower range, up to 15.01 cm. Plant heights might be controlled genetically, also environment could effect. Date of sowing was also significantly different from each other. Maximum height was found in D2 (50.78 cm), and minimum (44.15 cm) from D4. D1 and D3 showed 48.31 and 45.98 cm simultaneously. The result was supported by [18] Rasem et al., (2005) who reported that delay sowing significantly reduce the plant height. Primary branches per plant are an important yield contributing character. In case of V2, it was almost similar with finding of [11] , where it was reported that number of primary branch was 5 to 7. Also [16] Toncer and Kizil (2004) reported number of branch 4.7 to 6.8 per plant, which was almost similar to finding [19] . Tuncturk et al., (2011) reported 3.76 branches per plant. It might be depended on genetical as well as environment. In case of number of secondary branch [20] , Shah and Samiullah (2007) observed 7.2 to 11.74 branches per plant. Leaf area is the indicator of photosynthesis. Photosynthesis influences capsule setting, number of seed per capsule as a results production is increases. This result number of seed per capsule was in partial conformity with the findings of [16] Toncer and Kizil (2004) who reported that, number of seed per capsule varied from 90.7 to 92.8. Also, in case of V2, report from [11] BARI (2007) showed 75 to 80 seeds per capsule [15] Tuncturk et al., (2005) and [13] Shah et al., (2006) reported a few lower seed per capsule 66.45 to 71.72 and 52.01 to 52.17 respectively. It might be controlled genetically. In date of sowing, finding was supported by [17] Rahnavard et al., (2010) and [9] Sadeghi et al., (2009), who reported that, seed per capsule was higher in early sowing [18] . Rasem et al., (2005) found that delay sowing significantly reduced seed per capsule. Among yield contributing characters, number of capsule per plant is one of the most important. From this finding Slightly lower report were obtained from [21] Shah (2011) (16.45 ± 1.2), 15.12 by [22] Shah (2007), 9.48 to 14.65 by [15] Tuncturk et al., (2005) and 15.26 to 16.50 by [13] Shah et al. (2006). But very few number of capsule per plant (4.68) was reported by [19] Tuncturk et al., (2011), and very higher (42.13) by [23] Sardooyi et al., (2011). It might be controlled genetically. On the other hand, date of sowing also effect on capsule per plant. Finding was supported by [17] Rahnavard et al., (2010) and [9] Sadeghi et al., (2009), who reported that, capsule per plant was higher in early sowing [18] . Rasem et al., (2005) found that delay sowing significantly reduced capsule per plant. Each was statistically different from each other. 1000 seed weight is an important yield contributing character. The result was similar to finding of [19] Tuncturk et al., (2011) who reported 1000 seed weight was 2.28 g. Also the result was similar to [13] Shah et al., (2006) (2.45 to 2.50 g). In another experiment, [20] Shah and Samiullah (2007) described 1000 seed weight as 2.40 to 2.91 g. The result also mostly supported by [15] Tuncturk et al., (2005), who described 1000 seed weight as 2.40 to 2.65 g. A slightly low 1000 seed weight 1.79 to 1.89 g was found by [16] Toncer and Kizil (2004), and some higher as up to 5g, and up to 7g by [23] Sardooyi et al., (2011) and [11] BARI (2007) respectively. That might be due to genetic. In case of date of sowing, finding was supported by [17] Rahnavard et al., (2010), [9] Sadeghi et al., (2009), [18] Rasem et al., (2005) and [23] Sardooyi et al., (2011) who reported that, date of sowing had no significant effect or little on 1000 seed weight. Seed yield per hectare is the ultimate goal. The finding was supported by [24] Abdolrahimi et al., (2012), who observed seed yield up to 2.15 t/ha [20] . Shah and Samiullah (2007) described seed yield up to 1.55 t/ha. [14] Valabadi and Aliabadi (2011) found up to 1.43 t/ha. In case of date of sowing, finding was supported by [17] Rahnavard et al., (2010), [9] Sadeghi et al. (2009) and [23] ) Sardooyi et al., (2011) who reported that, early sowing gave higher yield. In case of stover yield, the finding was supported by [14] Valadabadi and Aliabadi (2011), who reported stover yield 3.49 to 4.23 t/ha. On the other hand, date of sowing clearly effect on stover yield. Finding was supported by [17] Rahnavard et al., (2010) and [9] Sadeghi et al., (2009) who reported that aboveground biomass was higher in early sowing. In every genotype, gradually late sowing gave gradually lower stover yield. Harvest index (%) is the indicator of efficient use of each genotype was statistically different from each other in harvest index. The finding was similar to observation of [23] Sardooyi et al. (2011), who reported 51% harvest index. [17] Rahnavard et al. (2010) also found 45% harvest index. But the findings of [20] Shah and Samiullah (2007), [13] Shah et al. (2006) and [24] Abdolrahimi et al., (2012) were few lower as 30.30% to 32.91%, 30.01% to 30.21% and 23.93 to 25.84% respectively, might be due to genotypic character. In an experiment in Azerbaijan, [24] Abdolrahimi et al., (2012) found strong correlation of seed with stem weight (0.99**), capsule weight (0.99**), seed weight (0.99**), 1000 seed weight (−0.69**), which support current findings [17] . Rahnavard et al., (2010), in his experiment showed strong correlation (r = 0.91**) between seed yield and aboveground biomass, but a negative one (r = −0.68*) between aboveground biomass and harvest index, which strongly support current finding. Finding of [9] Sadeghi et al., (2009), in Iran was strong correlation (r = 0.91**) between seed yield and above biomass, but a negative (r = −0.68*) with harvest index. Also these finding strongly support current findings. Correlation among various characters indicated that all these characters had significant contribution to seed yield and yield would be increased by improving these yield attributes.
4. Conclusion
The effect of planting time with genotypes was investigated to find out the suitable planting time in each genotype. The genotypes of black cumin showed variation in growth and yield behavior. Genotype V1 (Exotic) was found suitable for higher seed production. Genotype V4 (Natore local) was found as short durated and V1 long durated crop. Seeds of V1 (Exotic) and V2 (BARI kalojeera1) showed higher germination and higher vigor sowing in 1 November followed by 16 October obtained the highest yield, and sowing in 16 October took maximum duration for harvest.
NOTES
*Corresponding author.