Quality responses of winter wheat cultivars to nitrogen and fungicide applications in Croatia

Abstract

Winter wheat ( Triticum aestivum L.) cultivars may differ in grain quality responses to nitrogen (N) and fungicide applications, the two most important management inputs in the temperate climates of Europe. Limited information is available on N and fungicide effects on wheat quality in Croatia, where the wheat crop is widely grown under low N inputs without fungicide application. Field experiments were conducted during three years to evaluate the effects of fungicide (tebuconazol applied around heading) and two N fertilization rates on the grain quality of six widely grown winter wheat cultivars. Most cultivars failed to achieve the minimum breadmaking standards at a low N rate because of low protein content (103 g kg −1 ), Zeleny sedimentation (22.2 cm 3 ) and wet gluten (201 g kg −1 ). High N fertilization significantly increased these quality traits in all cultivars (an average of 21% for grain protein, 58% for Zeleny sedimentation and 40% for wet gluten). However, some cultivars with low genetic potential for accumulating grain protein failed to reach the breadmaking quality even at a high N rate when the N availability in the soil was limited by drought. Significant cultivar × N interactions existed for all grain quality traits, but were mainly associated with differences in the magnitude of the responses and less with the ranks. Five cultivars consistently showed increased falling number as the N rate rose, but these cultivar-specific responses to N fertilization were of much lesser magnitude than those across years. Fungicide application showed no effect on grain protein. Zeleny sedimentation, wet gluten or gluten index in all six cultivars tested, whereas one cultivar consistently showed decreased falling number after fungicide use. Only the hectolitre weights increased following fungicide application, especially for disease-susceptible cultivars at the high N rate. Thus, high N fertilization resulted in cultivar-dependent increases in protein content, Zeleny sedimentation, wet gluten and falling number, whereas fungicide application had no effect on grain quality except improved hectolitre weights.