Predicting yield losses caused by lodging in wheat

Lodging is a major limiting factor for wheat (Triticum aestivum L) production, yet few studies have investigated the mechanism by which it reduces yield. This paper tests the hypothesis that lodging-induced yield losses in wheat can be predicted by calculating the reduction in canopy photosynthesis that results from lodging-induced changes to the architecture of the canopy. An existing model of canopy photosynthesis has been further developed to account for the effect of lodging-induced changes to the canopy architecture on photosynthesis and grain yield. The model predicted that lodging at 90 from the vertical will reduce yield by approximately 61%. The ability of the model to predict lodging-induced yield losses was tested against observations made in three separate field experiments. The model predicted 71% of the variation in the proportion of yield lost due to lodging (Y-LOSS) and the best-fit line was not significantly different from the 1:1 relationship. Sensitivity analysis showed that the proportion of yield lost was relatively insensitive to the model parameters. As a result it was shown that a simplified model could be employed without losing predictive accuracy. Y-LOSS = Sigma(f)(i) (L-90 x 0.7 + L-65 x 0.3 + L-25 x 0.1)/n In this equation i and f are the 1st and last days of grain filling, L-90 is the proportion of crop area lodged at 85-90 degrees from the vertical, L-65 is the proportion of crop area lodged between 46 and 84 degrees L-25 is the proportion of crop area lodged between 5- and 45 and n is the number of days of grain filling. (c) 2012 Elsevier B.V. All rights reserved.