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 th is study were breeding line, dwarfing gene dose, soil type, and fertilizati on. A theoretical model describing the dynamic structural response of livin g plants was used to define margins of safety against global buckling, anch orage rotation, and tissue rupture. These relative safety factors were defi ned for each treatment in comparison with a tall wheat variety selected fro m a breeding line called Seri and grown in sandy soil with low fertilizatio n. Compared to this reference, the relative safety factor against global bu ckling was increased (+39%, p < 0.01), and the relative safety factor again st anchorage rotation was decreased (-11%, p < 0.025), by one allele of the dwarfing gene. The relative safety factor against tissue rupture was unaff ected 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 t he 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 vari eties are intrinsically more robust than others. Also, the relative safety factor against anchorage rotation was inversely proportional to the relativ e safety factor against buckling, which suggests that there are competing c onstraints on the dynamic structural behavior of wheat. (C) 2001 Academic P ress.