Effect of Some Agricultural Practices on the Productivity of Black Cumin (Nigella sativa L.) Grown under Rainfed Semi-Arid Conditions

Black cumin (Nigella sativa L.) plant is an annual spicy herb and belongs to the Ranunculaceae family. It has a rich nutritional value and has many medicinal usages. This study was conducted to investigate the effect of sowing dates, nitrogen fertilization rates and plant density on black cumin productivity under the rainfed semiarid conditions of Jordan. The factors were arranged in a split-split-plot in a randomized complete block design with three replicates and two locations. Results at Mushaqar location showed that planting on December 2 gave 25.1% and 54.1% more seed yield over planting at the end of December or at early January, respectively. Similarly, biological yield at the first date (December 2) was higher by 53.5% and 87% as compared to the 2nd and 3rd dates, respectively. Harvest index behaved differently, where the highest harvest index was obtained in 2nd and 3rd planting dates. At Maru location, highest harvest index value was obtained in second date with an increase of 29.2% and 33.5% over planting in 1st and 3rd date, respectively. Weight of 1000 seed was significantly affected by planting dates and plant density at the two locations. The highest 1000 seed weight at Mushaqar was obtained under 35 kg seed ha-1 followed by 25, 30 and 40 kg ha-1. Whereas at Maru, the highest seed weight was obtained under 30 and 35 kg seed ha-1. First planting date gave the tallest plants at Mushaqar, whereas 25 kg seeds ha-1 gave the tallest plants at Maru. Seed yield was significantly correlated at both locations with plant height and weight of 1000 seeds. Neither plant density treatments nor urea treatment applied at cultivation date showed significant effect on seed yield for the two locations