Effect of cultivar and soil characteristics on nutritional value in organic and conventional wheat

Evidence of greater nutritional value in organic crops is currently a subject of intense debate. Our objectives in this study were to test for grain mineral concentration in 35 winter wheat cultivars in paired organic and conventional systems, and to determine the influence of cultivar, soil characteristics and farming system on mineral concentration. Here we report preliminary results that show that the grain mineral concentration in organic wheat was higher for copper (Cu), magnesium (Mg), manganese (Mn), phosphorus (P) and zinc (Zn) and lower in calcium (Ca), than the grain mineral concentration in conventional wheat. No difference was found between systems for iron (Fe) concentration. Cultivar was significant in determining mineral concentration for Ca, Cu, Mg, Mn and P. Soil mineral concentration was not responsible for grain mineral concentration, with the exception of P. The organic wheat farming systems had higher grain mineral concentrations of Cu, Mg, Mn, P and Zn than the conventional systems, possibly due in part to increased soil organic matter and pH in the organic systems. Growing specific cultivars capable of exploiting particular soil conditions may be necessary in order to optimize the nutritional value in organic farming systems

Improving nutrient uptake in wheat through cultivar specific interaction with Azospirillum

Obtaining sufficient plant available nitrogen in organic dryland wheat cropping systems is difficult. This study was conducted to determine whether inoculation with Azospirillum could improve nitrogen uptake and increase crop yield, and whether there are differences among wheat cultivars in the ability to benefit from inoculation of these diazotrophic bacteria. Seed from twenty historic and modern wheat cultivars were either left untreated, or treated with a commercial inoculant of Azospirillum, and planted at two locations under certified organic management. In one location with lower fertility, inoculation significantly increased yield and protein, and clear differences existed among individual cultivars in response to the inoculant. In another location with higher fertility, none of the cultivars responded as favorably to the inoculant, and yield in some cultivars was reduced. Plant breeders should be able to select for beneficial cultivar interactions with Azospirillum to increase wheat yield and protein levels. Additional research is needed to determine the impact of site-specific soil conditions on the effectiveness of Azospirillum in organic systems