Received 11 April 2015; accepted 16 May 2015; published 20 May 2015

ABSTRACT

Black cumin (Nigella sativa L.; Family-Ranunculaceae) is an important spice crop. Mature seeds are consumed for edible and medical purposes and also used as a food additive and flavour. Seed of black cumin has great potentiality as spice crop due to nutritive and medicinal values. The experiments were carried out at Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur during 2011 to 2012 to determine optimum planting time for seed production of black cumin. 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. Result revealed that significantly the highest 2.37 t/ha in V₁, followed by V₂ (1.96 t/ha). V₂ and V₃ (1.97 t/ha) were statistically similar and maximum yield was obtained from D₂ (2.65 t/ha). In combined effect, maximum yield 3.00 t/ha was obtained in V₁D_2.. Investigation on time of sowing revealed that performance of black cumin was better in earlier sowings (16 October, 1 November) than later ones. The highest yield (4g plant⁻¹; 2.65 tha⁻¹) was obtained when the crop was sown on 1 November. Among the genotypes, the exotic one with sowing in 1 November gave the highest seed yield (4.54 g・plant⁻¹; 3.00 t・ha⁻¹).

Keywords:

Black Cumin, Flower Blooming, Capsule, Seed Yield, 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 P^H 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 1^st 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 1^st flower bud initiation: Days to 1^st 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 1^st flower blooming: Days to 1^st 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 1^st capsule setting: Days to 1^st 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 1^st 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 1^st Emergence

Variation among the genotypes was observed and the days to 1^st emergence ranged from 7.42 to 8.58 days (Table 1). The V₃ genotype took the highest days (8.58 days) to 1^st 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 1^st Flower Bud Initiation

There was clear significant different among genotypes in 1^st 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 1^st 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 1^st Flower Blooming

Significant variation was observed in V₁ with other genotype in days to 1^st 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 1^st flower blooming.

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 1^st Capsule Setting

Variation in days to 1^st 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 1^st 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

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 V_4. 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 1^st 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,

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.

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 D_2, 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

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.

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

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

^*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 1^st 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 1^st emergence (Figure 5) and than late sowing which influenced 50% emergence. Bud initiation, days to 1^st 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 1^st 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

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.

References

NOTES

^*Corresponding author.