NOTE: This item is not available outside the Texas A&M University network. Texas A&M affiliated users who are off campus can access the item through NetID and password authentication or by using TAMU VPN. Non-affiliated individuals should request a copy through their local library's interlibrary loan service.
The red:far-red ratio of solar radiation as an environmental signal regulating tiller recruitmnet in the bunchgrass Schizachyrium scoparium
MetadataShow full item record
Changes in the red:far-red ratio (R:FR) of solar radiation are an important environmental signal influencing dicotyledonous plant development. Recent studies conducted mainly in controlled environments also indicate that depressions in the R:FR relative to values typically measured in daylight reduce tiller recruitment from axillary buds in grasses. However, the mechanism responsible for reduced tiller recruitment and the site of photoperception of the R:FR signal on the grass tiller are not known. In addition, few attempts have been made to experimentally verify the significance of the R:FR in influencing tiller recruitment in grasses grown in the field. The experiments reported in this dissertation were designed to address these three problems utilizing Schizachyrium scoparium, a widely distributed native North American perennial bunchgrass. Tiller recruitment in S. scoparium seedlings grown in a controlled environment was temporarily delayed by end-of-day FR. The mechanism of reduced tiller recruitment appears to be assimilate diversion from buds to support end-of-day FR enhancement of leaf growth on existing tillers. Reduced tiller recruitment is therefore only one component of a major shift in allocation priorities induced by end-of-day FR which increases existing tiller height and leaf development. Emerging, immature leaf blades on the tiller were demonstrated to be the exclusive sites of end-of-day FR photoperception in S. scoparium seedlings. However, end-of-day FR enhanced not only the growth of the leaf which perceived the radiation signal, but also subsequent leaves on the same tiller. This carry-over effect allowed each tiller to respond to end-of-day FR as an integrated unit. In a field experiment, supplemental radiation provided beneath undefoliated and defoliated canopies of individual S. scoparium plants measurably altered the R:FR at plant bases, but failed to influence the magnitude of tiller recruitment as predicted. The results of experiments reported in this dissertation suggest that depressions in the R:FR slightly alter the timing of tiller recruitment and not, as has been previously suggested, its magnitude. Consequently, a depressed R:FR signal is probably of greater ecological significance in modifying the architecture of tillers and grass canopies in canopy shade than in regulating tiller recruitment from buds on existing tillers.
SubjectMajor plant physiology
Effect of radiation on
1993 Dissertation M978
Effect of radiation on
Murphy, Jeffrey Stephen (1993). The red:far-red ratio of solar radiation as an environmental signal regulating tiller recruitmnet in the bunchgrass Schizachyrium scoparium. Texas A&M University. Texas A&M University. Libraries. Available electronically from
Request Open Access
This item and its contents are restricted. If this is your thesis or dissertation, you can make it open-access. This will allow all visitors to view the contents of the thesis.