Relative safety factors against global buckling, anchorage rotation, and tissue rupture in wheat.

The objective of this study was to quantify the effect of specific physical and biological factors on the relative likelihood of biomechanical failure in wheat. Wind-related crop damage is a major obstacle to wheat production that costs several billion dollars per year. The four factors varied in this study were breeding line, dwarfing gene dose, soil type, and fertilization. A theoretical model describing the dynamic structural response of living plants was used to define margins of safety against global buckling, anchorage rotation, and tissue rupture. These relative safety factors were defined for each treatment in comparison with a tall wheat variety selected from a breeding line called Seri and grown in sandy soil with low fertilization. Compared to this reference, the relative safety factor against global buckling was increased (+39%, p<0.01), and the relative safety factor against anchorage rotation was decreased (-11%, p<0.025), by one allele of the dwarfing gene. The relative safety factor against tissue rupture was unaffected by the dwarfing gene but was consistently lower (-26%, p<0.01) in a second breeding line called Kauz. Soil type and fertility did not affect the relative safety factors and this negative finding was significant at p<0.05. The key finding was that the strength of wheat was affected more by genetic rather than by environmental factors, which suggests that some varieties are intrinsically more robust than others. Also, the relative safety factor against anchorage rotation was inversely proportional to the relative safety factor against buckling, which suggests that there are competing constraints on the dynamic structural behavior of wheat.

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