Assessing Factors Related To Yield Gaps In Flooded Rice In Southern Brazil

Identifying the causes of the yield gap (Yg) is essential to understand and take proactive measures to improve crop management factors. Brazil is the country in the Americas with the highest area of flooded rice (Oryza sativa L.) and the Rio Grande do Sul (RS) state accounts for 73% of the Brazilian rice production. The objective was to determine yield potential (Yp) and Yg in flooded rice and identify key factors associated with high yield (HY) and low yield (LY) farms across the rice production regions in RS, Brazil. Yield and management practices data from farmers were collected by a survey that included 324 site-year observations fields covering the five major RS production regions during three growing seasons (2016-2018). The Yp was simulated by Oryza crop model. The Yg was calculated as the difference between Yp and the average yield from farmers. Factors related between tertiles were studied by identifying management practices that were associated with high- and low-yielding fields. Rice Yp ranged from 14.2 to 15.9 Mg ha(-1) and the Yg was 48% of the estimated average Yp (15.1 Mg ha(-1)). Our findings indicated that HY fields had 33% higher productivity, rotated more area with soybean [Glycine max (L.) Merr.] (77%), controlled pre-sowing weeds by only herbicides (56%), sowed 20 d early with lower seeding rate (6%) and had early onset irrigation (5 d) compared to LY fields. These findings are applicable to rice farmers worldwide, and can help to define priorities in research and extension programs at both local and regional levels.