MEASUREMENT OF THE STEM PROPERTIES OF WHEAT TO INDICATE ITS LODGING RESISTANCE
Kareem, Shola Hassan 1988-
A major agronomic problem in wheat that has far-reaching economic consequences is lodging. Development of selective breeding tools that are dependent on abiotic and biotic factors could be the only reliable way to limit lodging. The objective of this research was to investigate new lines derived from a cross breeding of two wheat cultivars; AC Cadillac and Carberry, and observe the yield, traits and their correlation to lodging. The effect of moisture on the biomechanical traits was also investigated. The biomechanical traits of the selected lines were investigated using a three-point bending test procedure. The values for the biomechanical properties measured (bending strength, modulus of elasticity, and flexural rigidity) showed to decrease with increase in moisture content. The parent AC Cadillac showed to have higher strength values compared to Carberry in all blocks. The biomechanical values calculated for these lines were correlated with the lodging scores and morphological traits. Internode bending strength was positively correlated with density (r = 0.70, P < 0.05), slenderness ratio (r = 0.44, P < 0.05), and stem height (r = 0.43, P < 0.05) while flexural rigidity was positively correlated with stem wall thickness (r = 0.57, P < 0.05), and modulus of elasticity was positively correlated with density (r = 0.55, P < 0.05). At 14% moisture content, root lodging was positively correlated with bending strength, modulus of elasticity, and flexural rigidity (r = 0.41, P < 0.05, r = 0.39, P < 0.05 and r = 0.36, P < 0.05 respectively) while at 22% moisture content the lodging scores were positively correlated with bending strength, modulus of elasticity, and flexural rigidity (r = 0.17, P < 0.05, r = 0.24, P < 0.05 and r = 0.20, P < 0.05 respectively). Difference in strength values was found within replicates of the same line, which could be because of soil heterogeneity and anisotropicity of the wheat stems. The morphological traits of these selected lines were investigated using a laser length measuring device, weighing balance, and an imaging device. Lodging scores/numbers were assigned based on observation and discretion using a scale of 1-9. The morphological traits measured were stem height, length of the second internode, slenderness ratio, density, thickness, and volume. The height of the wheat stems, the slenderness ratio of the second internode, and density of the wheat stems showed positive correlation with lodging scores (r = 0.52, r = 0.30, r = 0.35 respectively, P < 0.05). The effect of insoluble carbohydrates (cellulose, hemicellulose and lignin) on lodging, morphological traits, and biomechanical traits were investigated using Fourier Transform Infrared Spectroscopy (FTIR). Twelve wheat stem lines were selected based on their bending strength values to be investigated for variation of insoluble carbohydrates, and their effect on lodging. Lines having high, intermediate, and low bending strength values were picked within the parents and the entire new population derived. It was observed that there was no significant correlation between these insoluble carbohydrates and lodging. Stem height and density of wheat stem are key morphological traits to look at when considering plant breeding techniques in creating a lodging resistant variety. However other internal components could be researched and correlated to lodging as insoluble carbohydrates showed no significant correlation to lodging in this study.
Lodging, Biomechanical properties, Morphological Properties, Insoluble Carbohydrates.
Master of Science (M.Sc.)
Chemical and Biological Engineering