Effect of Seed Rate and Variety on Yield and Yield Contributing Traits of Black Cumin (Nigella sativa L.) at Andracha Woreda, Southwestern Ethiopia

Abstract

Black cumin is grown as one of Ethiopia's main seed spice crops. But its production and productivity are constrained by a shortage of improved varieties and poor cultural practices including seed rate. Therefore, studies were carried out in Andracha woreda of southwestern Ethiopia during the 2017 and 2018 major cropping period of year to identify the top-performing genotypes of black cumin (Nigella sativa L.) in response to seed rate. The experiment composed of four varieties (Dirshaye, Darbera, Aden, and local), and four levels of seed rate (10kg, 15kg, 20kg, and 25kg per ha) set out in a randomized complete block design and replicated three times. The findings of the statistical analysis exhibited that the majority of the response variables under consideration were significantly (P<0.01) influenced by seed rate, variety, and interaction of both factors except for days to maturity, plant height, and thousand seed weight. Based on the over-year combined analysis, the highest capsule number per plant (10.4), yield per plant (2.46), and total yield (703.9kg/ha) were noticed for the Darbera variety treated with a 15 kg/ha seed rate. The highest seed number per capsule (87.2) was also recorded for this treatment in the 2017 growing season. Essential oil (0.85 in 2017 and 0.65% in 2018) and oleoresin (29.4 in 2017 and 29.8% in 2018) content of this treatment met the international standard even though maximum recorded essential oil content was 0.92% in 2017 and oleoresin content was 33.8% in 2018. Therefore, concerning overall traits, it can be concluded that the Darbera variety combined with a 15kg/ha seed rate can be suggested for production in the research region.