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Defoliation effects of grain sorghum relating to yield components, grain filling, stem rot, lodging, nonsenescence, and stem morphology
Abstract
Defoliation responses of grain sorghum hybrid (Sorghum bicolor (L.) Moench) yield components, grain filling traits, nonsenescence, stem rot, and lodging were studied in three eastern Nebraska environments. Four intensities of defoliation (0, 50, 95, and 100%) were applied at $-$10, 0, 10, and 20 days post-anthesis. Defoliation decreased yield components, grain fill rate, grain fill duration, and nonsenescence duration while increasing stem rot severity. Significant defoliation intensity x defoliation time interactions occurred for all traits. Large defoliation x environment interactions for lodging suggested that several environments may be needed for evaluating defoliation effects on standability. Stem rot response to defoliation was similar in all environments. In another study, defoliation (0, 50 and 100% at 10 days post-anthesis) and nitrogen (0, 84, and 168 kg/ha) treatments were applied to eight sorghum hybrids which had been previously classified for yield stability. Hybrid x defoliation interactions were detected for grain yield, seed weight, grain fill rate, grain fill duration, and nonsenescence duration. Although hybrids differed in stem rot and lodging, their responses to increased defoliation were similar for these traits. Hybrids differed significantly in their lodging response to added nitrogen. Defoliated hybrids which flowered later tended to have higher yields, less lodging, and a shorter nonsenescence duration after anthesis. Defoliation may be a useful technique for evaluating genotype differences in stem rot and lodging in environments which lack sufficient stress for these traits to be observed. Scanning electron microscopy was used to study anatomical and morphological changes associated with stem rot development. Morphological development of stem rot was characterized as a low infection (LI) response or a general infection (GI) response. The LI response had limited fungal colonization and vessel element occlusions. The GI response exhibited mass fungal colonization and did not have vessel occlusions. Smooth membranous and fibrillar gel-like wall coatings were observed in both healthy and stem rotted plants.
Subject Area
Agronomy|Botany
Recommended Citation
Rajewski, John Francis, "Defoliation effects of grain sorghum relating to yield components, grain filling, stem rot, lodging, nonsenescence, and stem morphology" (1988). ETD collection for University of Nebraska-Lincoln. AAI8904508.
https://digitalcommons.unl.edu/dissertations/AAI8904508