Applications of foliar fertilizers containing glycinebetaine improve wheat yields

Nitrogen availability and drought influence wheat (Triticum aestivum L.) grain yields in the semiarid and subhumid Pampas region of Argentina. The application of fertilizers containing osmoprotectants, such as glycine-betaine, to crop canopies might reduce crop losses caused by environmental stresses. The objectives of this study were (a) to determine the effects on wheat grain yields of the foliar application of a commercial fertilizer with glycine-betaine, and (b) to establish, under farmers' field conditions, the relation between soil properties and the productivity of wheat crops treated with the same product. Two experiments were conducted in the north-western part of the Buenos Aires province of Argentina on Typic Hapludolls and Entic Hapludolls. In the first, the treatments were N fertilization (0, 23 and 46 kg ha(-1)) and the foliar application to the wheat crop, in the vegetative stages, of a foliar fertilizer containing N, P, Zn and glycinebetaine (0 and 2.51 ha(-1)). The second experiment was carried out on 10 farmers' fields, for each of which the treatment was the foliar application to the wheat crop, in the vegetative stages, of the same foliar fertilizer (0 and 2.51 ha(-1)). In both experiments, the grain yield, the individual grain weight, the number of grains per spike and the spike and plant density at the physiological maturity of the crops were determined. Soil organic matter (SOM) and available P were determined in each of the 10 fields of the second experiment. Wheat grain yields were increased by N fertilization and glycinebetaine treatment. The number of grains per spike was higher in the treatments with glycinebetaine application. In the farmers' fields, the grain yields of the treatments with the application of the product with glycinebetaine were, on average, 18% higher than those of the non-treated plots, with greater responses at sites with low SOM levels. We conclude that, in subhumid regions with a dry period between the tillering and flowering stages of wheat, the foliar application of foliar fertilizers containing glycinebetaine at the vegetative stages of crop development enhances grain yields by increasing the number of grains per spike. This response is independent of the SOM level or the N fertilization rate.