Hybrid sunflower seed yield, composition and deterioration after chemical desiccation

The impact of chemical desiccation on yield showed contrasting results depending on seedmoisture content at the time of application. Its effects on seed deterioration are still unknownand could be modified by seed composition. Objectives were to evaluate the impact of chemicaldesiccation on: i) hybrid sunflower seed yield and composition at harvest time, ii) seeddeterioration during long-term storage and iii) the relationship between seeds deterioration andoil or oleic acid content. Six hybrids including low, mid and high oleic were evaluated in threeexperiments. Two treatments were applied on female lines at 27-30% seed moisture:(i) spraying with Paraquat and (ii) detaching heads with a knife. Control remained in the fielduntil 10% seed moisture. Seeds were stored during 19 months under room and cold chamberconditions. Yield, number of seeds and hybrid seed composition (thousand seed weight, kernelpercentage, oil and acid oleic content) were determined. Seed deterioration during storage wasanalyzed by germination and vigour. Paraquat advanced harvest by 35-43 days, withoutaffecting yield or seed composition. During storage the germination of Paraquat treatmentsremained above that of control, without differences between storage conditions, while vigourremained above control only in cold chamber, for low oleic hybrids. Associations betweendeterioration (germination and vigour) and oil or oleic acid content, were not significant.Desiccation with Paraquat allows advanced harvest without yield losses or modifications in seedcomposition. The deterioration of desiccated seeds was lower and independent from oil andoleic acid content.