Weed management of Black seed (Nigella sativa) using barley (Hordeum vulgare) and Berseem clover (Trifolium alexandrinum) living mulchs

A field experiment was conducted to evaluate the effect of barley (Hordeum vulgare) and berseem clover (Trifolium alexandrinum) cover crops, and their cutting time on black seed (Nigella sativa) weed management in 2016-2017 at research field of the College of Aburaihan, University of Tehran. The experiment designe was randomized complete block design with 3 replications. Treatments were: T1, no cover plant-weed free; T2, no cover plant- weed infest; T3, barley-first cutting; T4, barley-second cutting; T5, clover-first cutting and T6, clover-second cutting. The first and the second cutting were done after Black seed establishment and before flowering stage of cover crops, respectively. Results showed that the highest weed biomass was 444 gr.m-2 obtained from T2 treatment at t the second sampling time and the lowest weed biomass was 28 gr m-2, related to first cutting clover treatment (T5), at the first sampling time. The highest grain yields were 527 and 446 kg.ha-1, observed in treatment (T5) and control treatment (T1) respectively and the lowest yield was obtained from control (T2) with a mean of 100 (kg ha-1). Overall, results showed that T5 treatment at the second sampling time reduced weed biomass 90.4% compared to without weeding control. In addition, the berseem clover plant not only did not compete with black seed, but also increased yield compared to the without cover plant control (T1).