Screening of sunflower germplasm against head rot disease and its management through resistance inducer chemicals

Being heavy importer of edible oil, Pakistan needs a strong development of its oilseed sector. Sunflower the fourth largest oilseed crop in the world, is sparsely cultivated on a limited acreage in Pakistan. The development of efficient production system of sunflower can fulfill the country's edible oil requirements. However, inadvertent losses due to various fungal diseases are an obstacle in sunflower production. Head rot disease caused by Rhizopus arrhizus is one of the most destructive fungal disease of sunflower. As an aim of this study, efficient and environment friendly management of this disease is envisaged by activating the systemic resistance of sunflower plants against the disease by the application of resistance inducing chemicals. Twenty one lines/varieties of sunflower germplasm (FH-331, FH-465, FH-572, FH-593, FH-425, FH-607, FH-608, FH-617, FH-618, FH-613, FH-622, FH-611, FH-612, FH-545, FH-551, FH-620, FH-557, FH-621, FH-607, FH-615, FH-609) were collected from Ayub Agricultural Research Institute, Faisalabad. Among twenty one, one line FH-621 exhibited resistant response, while three lines i.e. FH-593, FH-618 and FH-611 showed moderately resistant response. Twelve lines namely FH-425, FH-607, FH-608, FH551, FH-615, FH-609, FH-622, FH-612, FH-620, FH-545, FH-617 and FH-614 exhibited susceptible response, while 5 lines FH-331, FH-613, FH-465, FH-557 and FH-572 expressed highly susceptible response. Seven resistance inducing chemicals (Ascorbic acid, Salicylic acid, Benzoic acid, Oxalic acid, Zinc sulphate, Citric acid and Hydrogen peroxide) were evaluated at various concentrations in field for their efficacy to induce systemic acquired resistance (SAR) in sunflower against head rot disease. Among these chemicals (Ascorbic acid, Salicylic acid, Benzoic acid, Oxalic acid, Zinc sulphate, Citric acid and Hydrogen peroxide), 3mM of Salicylic acid gave maximum disease reduction (54.63%) while hydrogen peroxide at 1mM concentration showed minimum disease reduction (20.26%).