Sunflower yield gaps and their causes in Argentina

Abstract

Context: Quantification of yield gaps and understanding their causes in sunflower (Helianthus annuus L.) is a key requirement for developing management strategies to take advantage of the productive potential of this crop in Argentina. The term yield gap (Yg) refers to the difference between water-limited potential yield (Yw) and actual yield (Ya). Objective: This study quantified sunflower Yg across its full range of cropping regions of Argentina and used the results to identify potential causal factors. Methods: This study, structured around component climate zones, proceeds in two steps. In the first, Yg is calculated by three methods according different Yw estimators: (i) yield simulations using CROPGRO-Sunflower model; (ii) top yields of comparative yield trials; and (iii) top yields of farmer’s paddocks. Corresponding Ya values were estimated from national statistics. In the second, an independent database was established from the Relevamiento de Tecnología Agrícola Aplicada. Regression trees were used to explore associations between technological variables and estimated Yg. Results: National sunflower Yg remained consistent across the different Yw estimation methods: 34 % via simulated yields, 40 % using comparative yield trials, and 34 % based on farmer’s paddock yields. Tillage system, phosphorus fertilization, and the adoption of herbicide- resistant and high oleic cultivars were key factors in explaining the smaller sunflower Yg in Argentina. Conclusions: Argentina has the potential to substantially increase its sunflower grain production, and key factors to increase current production were identified in this work. Implications: Increased sunflower production could boost Argentina’s exports, contributing significantly to its economy. The identified factors pave the way for designing practices that help farmers bridge the yield gap.