Effects of Plant Density and Leaf Spraying o Growth, Yield and Yield Components of Flixweed (Descurainia sophia L.) as a Medicinal Plant

Biodiversity of medicinal and aromatic plants contributes significantly towards human livelihood and development and thus plays a predominant role in the wellbeing of the global population. According to WHO reports, around 80 % of the global population still relies on traditional medicines and natural substances. Descurainia sophia L. seed, also known as flixweed, a commonly used herbal medicine in Iranian folk medicine is one of those medicinal herbs with prevalent use. Agronomic practices are required to be standardized for realizing yield potential. Among the different agronomic practices, foliar spray of macronutrients is most important factor in determining the yield. Plant density is another important agronomic factor that manipulates micro- environment and affects growth, development and yield of plants. Within certain limits, increase of plant population density declines the growth and yield per plant but the reverse occurs for yield per unit area. The optimum plant density to attain highest yield may vary with the genotype and agronomic factor. Hence the purpose of this study was to determine the effects of plant density and leaf spraying on growth, yield and yield components of flixweed under Torbat-e Jam climatic conditions. In order to study the effects of plant density and leaf spraying of growth, biological yield, seed yield, yield components and harvest index of flixweed, an experiment was conducted as factorial layout based on a randomized complete block design with three replications at the Agricultural Research Station, Azad University of Torbt-e Jam, Khorasan-e Razavi during growing season of 2016-2017. Treatments included four plant densities (10, 20 and 40 plants.m-2) and leaf straying at three plant stages (such as emergence, before flowering and early seed formation stages) and control (without spraying). Leaf spraying was done using complete fertilizer (5:1000). Studied traits were plant height, number of branches per plant, 1000- seed weight, seed yield, biological yield, dry weight of shoot, fresh weight of shoot and harvest index. The treatments were run as an analysis of variance (ANOVA) to determine if significant differences existed among treatments means. Multiple comparison tests were conducted for significant effects using the Duncan’s test. The results showed that the simple effect of plant density was significant (p≤0.05) on number of branches per plant and harvest index of flixweed. The simple effect of foliar spraying was significant (p≤0.05) on number of branches per plant and 1000-seed weight of flixweed. The interaction effect between plant density and foliar spraying had significant effect on number of branches per plant, dry weight of shoot, seed yield, biological yield and harvest index of flixweed. The highest seed yield, biological yield and dry weight of shoot were recorded in 40 plants.m-2+ foliar spraying at early seed formation with 99, 495 and 396 g.m-2, respectively. The minimum seed yield was observed in 10 plants.m-2+ without spraying with 35 g.m-2. The lowest biological yield and dry weight were obtained in 20 plants.m-2+ foliar spraying at early seed formation with 168 and 126 g.m-2, respectively. The results for correlation coefficients between yield and yield components revealed that the highest coefficient was calculated for biological yield and dry weight of shoot (r=0.97**). Agronomic management strategies had significantly effect on growth, yield, and yield components of flixweed. Generally, plant density and nutrient management are two effective techniques for agronomic management of medicinal plants such as flixweed that may decline the necessity for chemical and intensive approaches to the plant. The findings of the present study indicate that foliar spraying would be an advisable treatment that produces higher seed yield. In total, according to the results, the plant density of 40 plants.m-2+ foliar spraying at early seed formation is recommended to realize maximum seed yield flixweed cultivation in Torbat-e Jam region, Iran.