An Important Step Toward Solving Maize Lodging: Engineering Failure Analysis Identifies a Consistent Stalk Weakness.

Introduction:

Stalk lodging accounts for a 5-20% loss of maize crop each year.  Stalk lodging has proven to be a persistent agricultural problem, due to complex interactions between environmental, biological, and abiotic factors.  Genetic relationships that influence lodging are similarly complex, with low levels of heritability.  Previous efforts to quantify stalk strength and lodging have taken a biological approach, often focusing on the effects of nutrients, husbandry, and gross physiological features.  This study describes the application of engineering failure analysis techniques to stalk lodging.

Methods:

Engineering failure analysis typically involves: (i) careful observations of failed specimens; (ii) identification of different failure patterns; (iii) development of a classification methodology, and (iv) data collection to determine the frequency of each failure type as well as failure locations.  These activities were performed by structural engineers. Recorded data included type of failure, location of failure relative to the ground, ear, and nearest node, failure direction, etc.

Results:

Observational data collection of naturally occurring instances of stalk lodging were conducted in 2 years, 8 locations, 2 continents (North America, Africa), included over 20 hybrid varieties, and spanned a variety of planting densities. The composite data revealed valuable patterns.  First, over 75% of all observed failures occured within 2cm of a node. Patterns of failure height above the ground were much broader, with no identifiable pattern detected in failure location.  Subsequent geometric analysis using high-resolution x-ray scanning revealed several geometric and tissue patterns that could potentially weaken the stalk structure. 

Conclusions:

This study represents the first application of an engineering failure analysis to the problem of crop lodging.  Lodging consistently occurs near nodes, regardless of environment, hybrid type, weather, and planting density.  While more research is needed, the successful strengthening of this region of the stalk could have broad implications of improved crop productivity worldwide.