Response of Branched Broomrape (Phelipanche ramosa (L.) Pomel) to Amino Acid Treatments

Abstract Phelipanche ramose (branched broomrape) , a root holoparasitic weed causes great trouble in agriculture along Mediterranean, Europe, Asia, Africa, North and South America, cannot be easily controlled by the known management practices applied for non-parasitic weeds. Determination of novel compounds with higher herbicidal activity against P. ramosa can provide effective control for this parasitic weed. Certain amino acids have potential to inhibit early development of broomrape without any injury to host plants. A series of pot and in vitro studies were conducted to identify amino acids with higher inhibition efficacy on broomrape germination and growth. Germination inhibition rates of amino acids were significantly different. The highest inhibitory rates were obtained from alanine, lysine and tryptophan, while the lowest was obtained from theanine, leucine and isoleucine under the in vitro conditions. The inhibitory effect of amino acids on germination enhanced with the increasing concentrations. In the polyethylene bag studies, the number of germinated seed per plant varied between 46.00 and 205.50. The lowest and the highest germinated seeds were obtained from proline and theanine, respectively. Tubercle number per plant varied between 0.00 and 3.50. Glutamic acid had the highest tubercle number, while leucine, glycine, tryptophan and isoleucine had the lowest tubercle number per plant. In general, lysine, proline, phenylalanine, asparagine are thought to the most effective inhibitors of brunched broomrape germination. Further studies are needed to evaluate the usefulness of amino acids in P. ramose control under field conditions.