Bristly Oxtongue (Helminthotheca echioides (L.) Holub) Responses to Sowing Date, Fertilization Scheme, and Chitosan Application

Abstract

Bristly oxtongue (Helminthotheca echioides (L.) Holub) is a broad-leaved weed species that is commonly found in cereal crops. However, it is also an edible species whose leaves are consumed at the rosette growth stage of the plant. Three pot experiments were conducted to evaluate different cultivation protocol suggestions for this underutilized wild leafy vegetable. In the first experiment, early sowing (14 October) increased the rosette diameter and fresh biomass of bristly oxtongue compared with late sowing (13 November). In the second experiment, the application of calcium ammonium nitrate (26-0-0) at a rate of 100 kg ha−1 (N10 treatment) increased the relative chlorophyll content in the leaves compared with the control treatment. Similarly, the highest rosette diameter, leaf number, and fresh biomass values were recorded in the N10 treatment, while chitosan application had no impact on growth of plants. In the third experiment, increased root dry biomass was obtained with top dressing application of calcium ammonium nitrate at a rate of 100 kg N ha−1 compared with 0 or 50 kg N ha−1, regardless of the basal fertilization (15-5-20) rate applied. Moreover, the highest rosette diameter, relative chlorophyll content, and fresh biomass values were recorded in the treatment where the highest top dressing rate of calcium ammonium nitrate was applied. In conclusion, our results reveal that the appropriate selection of the sowing date, as well as the combination of the basal fertilizer (15-5-20) at a rate of 250 kg ha−1 with 100 kg N ha−1 calcium ammonium nitrate, can maximize the growth and yield of bristly oxtongue.