Problems associated with increasing trends towards high micronaire values for Upland cotton (Gossypium hirsutum L.) have been a matter of concern for the Arizona cotton industry in recent years. The discounts on fiber value associated with high micronaire has been compounded by the fact that market prices for cotton fiber has been very low in recent years and yields have been stable at best. An evaluation of recent yield and fiber quality data from a number of locations in Arizona was evaluated in relation to trends within Arizona and across the U.S. cotton belt. Results indicate similar patterns exist in terms of stable yields (yield plateau) and increasing micronaire values between Arizona and other U.S. cotton producing states. The conclusion is presented that these patterns are at least due in part to a common genetic base for varieties that grown in Arizona and beltwide. There also appears to be some distinct relationships associated with high micronaire with region and individual farm management practices.

A field trial was conducted to study the elements of application timing and herbicide compatibility in the use of Burst, a plant growth regulator, and the effects of these two factors on yield of upland cotton. Eight treatments combined the two factors of timing and tank mix. The results showed no significant difference in yield between treatments.

The recommended procedures for implementing COTMAN; a cotton management expert system; suggest frequent crop scouting at numerous locations for each field. Machine based height sensors coupled with the ability to spatially record height values make it possible to locate regions of a field that are height representative of the entire field. A machine based height measurement system called HMAP was used to assess plant height in various fields in the 2003 growing season while the same fields were monitored with COTMAN. The plant height data was used to determine an optimal COTMAN sampling scheme for each field consisting of significantly fewer sampling locations than recommended by COTMAN. It was possible to ascertain equivalent information from COTMAN using two sites selected from height data in place of six sites selected per COTMAN recommendations. The HMAP system was extended to monitor rate of growth in real time in addition to plant height by comparing historical plant height data recorded on previous field passes to current height values. The rate of growth capable HMAP system will make it possible to track cotton growth and development with an automated system.

No description available.

The recommended procedures for implementing COTMAN; a cotton management expert system; suggest frequent crop scouting at numerous locations for each field. Machine based height sensors coupled with the ability to spatially record height values make it possible to locate regions of a field that are height representative of the entire field. A machine based height measurement system called HMAP was used to assess plant height in various fields in the 2003 growing season while the same fields were monitored with COTMAN. The plant height data was used to determine an optimal COTMAN sampling scheme for each field consisting of significantly fewer sampling locations than recommended by COTMAN. It was possible to ascertain equivalent information from COTMAN using two sites selected from height data in place of six sites selected per COTMAN recommendations. The HMAP system was extended to monitor rate of growth in real time in addition to plant height by comparing historical plant height data recorded on previous field passes to current height values. The rate of growth capable HMAP system will make it possible to track cotton growth and development with an automated system.

Thesis (Ph.D.) - University of Queensland, 2004. / Includes bibliographical references.

Plant architecture is an important agronomic trait driven by meristematic activities. Indeterminate meristems set repeating phytomers while determinate meristems produce terminal structures. The centroradialis/terminal flower1/self pruning (CETS) gene family modulates architecture by controlling determinate and indeterminate growth. Cotton (G. hirsutum) is naturally a photoperiodic perennial cultivated as a day-neutral annual. Management of this fiber crop is complicated by continued vegetative growth and asynchronous fruit set. Here, cotton CETS genes are phylogenetically and functionally characterized. We identified eight CETS genes in diploid cotton (G. raimondii and G. arboreum) and sixteen in tetraploid G. hirsutum that grouped within the three generally accepted CETS clades: flowering locus T (FT)-like, terminal flower1/self pruning (TFL1/SP)-like, and mother of FT and TFL1 (MFT)-like. Over-expression of single flower truss (GhSFT), the ortholog to Arabidopsis FT, accelerates the onset of flowering in Arabidopsis Col-0. In mutant rescue analysis, this gene driven by its native promoter rescues the ft-10 late flowering phenotype. GhSFT upstream sequence was used to drive expression of the uidA reporter gene. As anticipated, GUS accumulated in the vasculature of Arabidopsis leaves. Cotton has five TFL1-like genes, all of which delay flowering when ectopically expressed in Arabidopsis; the strongest phenotypes fail to produce functional flowers. Three of these genes, GhSP, GhTFL1-L2, and GhBFT-L2, rescue the early flowering tfl1-14 mutant phenotype. GhSPpro:uidA promoted GUS activity specifically in plant meristems; whereas, other GhTFL1-like promoters predominately drove GUS activities in plant vascular tissues. Finally, analysis of Gossypium CETS promoter sequences predicted that GhSFT, GhSP, GhTFL1-L1, GhTFL1-L2 and GhBFT-L2 are regulated by transcription factors involved in shoot and flowering development. Analysis of cotton's two MFT homologs indicated that neither gene functions to control shoot architecture. Our results emphasize the functional conservation of members of this gene family in flowering plants and also suggest this family as targets during artificial selection of domestication.