|09-545 Project Manager: D. C. Jones|
ASSOCIATING MOLECULAR MARKERS WITH NEWLY MEASURABLE FIBER TRAITS
Steven S. Hague, Texas AgriLife Research
The temporal system of fruiting on the cotton plant lends itself to bolls at different fruiting sites developing under different environmental conditions and with varied source-sink relationships. To investigate this, intra-plant fiber quality was assessed in four upland cultivars at College Station, Texas for three years and at Lubbock, Texas for two years. It was concluded that fiber quality steadily declines from the bottom sympodial branches towards the upper branches. 'FiberMax 832' had the best fiber quality among all cultivars, but it also had the highest degree of variability within the plants. 'Half and Half' and 'Acala 1517-99' appear to have the least amount of intra-plant variability of fiber quality. Bolls from the bottom region of the plant have higher trash content compared to the upper region. To test the impact of fiber quality variability on boll sampling techniques employed, ten sampling protocols were compared against each other for three years in College Station, Texas, for two upland cultivars. Results suggest that randomized boll samples containing 50 bolls worked well to estimate inherent fiber quality for most fiber traits while estimation of trash and lint percent was not predictable based on boll samples.
One of the problems associated with intra-plant fiber variability is immature fiber. To attempt improvement of fiber maturity in cotton, five upland cotton (Gossypium hirsutum L.) genotypes were subjected to diallel analysis to determine the potential for improvement of fiber maturity and standard fineness, at College Station, Texas, in 2011. Four cultivars that tend to produce fine and mature fibers and one cultivar that tends to produce coarse fibers were intermated in all combinations, without reciprocals. Estimates of general (GCA) and specific combining ability (SCA) for fiber maturity ratio and standard fineness based on Griffing's diallel Model I, Method 4 were calculated for AFIS and fiber micronaire, length and strength measurements for High Volume Instrument (HVI). Four parents had significant GCA effects and Acala 1517-99 was found to be the best parent for improving standard fineness followed by FiberMax 832 and 'Tamcot HQ-95'. Tamcot HQ-95 was the best parent to improve fiber maturity ratio while 'Deltapine 90' was the best parent to reduce fiber maturity ratio. The specific cross between Acala 1517-99 and Tamcot HQ-95 had the best performance. Diallel analysis indicated that fiber maturity ratio was influenced by non-additive gene effects more than additive gene effects while fiber standard fineness was highly influenced by additive gene effects.
Heritability estimates of fiber quality associated with this diallel population indicated that the HVI system of fiber measurement was more heritable than most AFIS derived measurements except for fiber fineness. While AFIS is generally assumed to provide a more complete measure of fiber quality, the effectiveness of fiber quality improvement using HVI with this particular population was superior to AFIS. It is unknown if this year and population was an atypical example of the reliability of AFIS to assess fiber quality and aid in the improvement.
This completes this project which resulted in four presentations/abstracts in proceedings, two manuscripts under development for peer reviewed publication, and one student who graduated with a PhD. The population developed from this project will provide breeding material for the program, and remnant seed will be maintained for for genomic studies.
|Project Year: 2012|
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