Does tillering affect the grain yield of maize (Zea mays)? A quantitative review

Context. Tillering is generally considered counterproductive for grain yield in maize (Zea mays). However, recent research defies that idea and suggests that the effects of tillering on grain yield depend on the yield-environment. Aims. To synthesise the impact of tillering on maize grain yield across a wide range of environments. Methods. Literature regarding tillering in maize was assessed to create a multi-environment database of grain yield per unit area and per plant of side-by-side comparisons of grain yield of tillered versus de-tillered treatments. Regression analyses and mean comparisons were used to compare the performance of tillered and de-tillered crops. Key results. The maximum plant density in the database was 7 plants m(-2). Tillered crops out-yielded de-tillered crops irrespective of the de-tillered grain yield (y-intercept = 841 kg ha(-1), P < 0.01 and slope = 1, P = 0.91). For the lower tercile of yield-environments (i.e. lower than 5269 kg ha(-1)), the frequency of lower yields on tillered crops was higher (all database = 0.21, Pampas = 0.5) than in the mid or high terciles (all database < 0.13, Pampas < 0.18). Across environments, individual plant yield was higher for tillered crops (42 g plant(-1) or 16% difference), but that difference decreased as the de-tillered individual plant yield decreased turning into zero below 136 g plant(-1). Conclusions. Within the limitations of the data set, tillering was generally beneficial or indifferent for grain yield, but detrimental effects may be recorded in very low yield-environments. Implications. Tillering does not condition maize yield across most environments.