dc.description.abstract |
Black cumin is a seed spice cultivated in Ethiopia for a long period of time. It is also
cultivated in Goro district of Bale Zone by small land holder farmers. However, expected
benefit of this crop is not being obtained by farmers since they are using in-appropriate
agronomic practices such as inappropriate seed rate without any fertilizer application.
Therefore, a field experiment was conducted in Goro district, south Eastern Ethiopia. The
objective of the experiment was to determine the effect of different seed rate and mineral
nitrogen and phosphorus fertilizer on yield, yield component, and essential oil contents of
black cumin. The treatments consisted of three seed rates (15, 20, 25 kg ha-1), three of
nitrogen fertilizer levels (0, 46, 92 kg N ha-1), and three phosphorus fertilizer levels (0, 46,
92 kg P2O5 ha-1). The experiment was laid out in Randomized Complete Block Design and
replicated three times per treatment. Analysis of variance showed that, the main effect of
seed rate significantly (P <0.05) influenced Days to flowering (DF), number of capsule per
plant (NCPP) and number of seed per capsule (NSPC). Accordingly, highest DF (86.7
days), highest NCPP (12.59) and highest NSPC (76.1) were obtained with 15 kg ha-1
seeding rate. Similarly, the main effect of nitrogen fertilizer rate significantly influenced
DF, days to maturity (DM), NCPP, number of primary branches (NPBPP), NSPC and
thousand seed weight (THSW). Highest DM (127.3 days), highest NPBPP (4.95), highest
NCPP (14.14), highest NSPC (76.51), highest THSW (2.34 g) was obtained with 92 kg ha-1
nitrogen fertilizer rate. The interaction effects of seeding rate, nitrogen fertilizer, and
phosphorus fertilizer significantly influenced plant height (PH) where, the maximum PH
(53.13 cm) was recorded at the seeding rate of 20 kg ha-1 combined with the application of
46 kg N ha-1 and 46 kg P2O5 ha-1. The interaction effects of seeding rate and phosphorus
fertilizer significantly (P < 0.01) influenced aboveground biomass (BM) and the seed yield
(SY). As a result the highest BM (3.98 ton ha-1) and highest SY (1152 kg ha-1) was obtained
with 20 kg ha-1 seeding rate combined with 46 kg ha-1 P2O5 fertilizer rate. Essential seed
oil content of the crop was affected neither by the main nor the interaction effects of all
factors. Partial budget analysis showed that, the treatment with 20 kg ha-1 seeding rate
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combined with 46 kg P2O5 ha-1 resulted in the highest marginal rate of return (1263%) and
maximum net benefit (75060 ETB ha-1). Thus, it could be concluded that establishing black
cumin plants with the seeding rate of 20 kg seed ha-1 and application of 46 kg P2O5 ha-1
resulted in the best growth and seed yield of the crop with optimum economic benefits. |
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