The evaluation and inheritance of several traits associated with lint percent in cotton
Shields, E. M.
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The relationship of within-boll components, lint percent and yield is not well defined. A better understanding of the relationship and how the traits react to selection should provide tools and methods the plant breeder could use to improve the efficiency of identifying superior lines with increased yield and enhanced fiber quality in early generations. This study was initiated to examine the heritability and relationship of within-boll components, lint percent, fiber quality and lint yield. The study was conducted during the years 2004, 2005, and 2006. Ten elite and obsolete cultivars were selected to be intercrossed in a half-diallel mating scheme. A parental evaluation was conducted during the first year of the study, parents, F2 populations and individual plant selection (IPS) were evaluated the second year; and parents, F2 populations and F2:4 lines were evaluated the third year. The characteristics measured were within-boll components, yield, agronomic properties and fiber properties. Six of the ten parents were selected for more detailed studies. Divergent selection was used to select the top and bottom 10% of plants for lint percent from each F2 population. These data were used to correlate F2 individual plant data with corresponding F2:4 line data. The parents were found to be diverse in lint percent, fiber characteristics and within-boll components. FM X9740 and DP 491 are comparable high yielding lines, however FM X9740 does not have the same high lint percent as DP 491. When studying the within-boll characteristics, factors contributing to the high yield of FM X9740 became evident. FM X9740 has a significantly larger seed compared to DP 491, lower number of seed per boll, but larger surface area per seed. Therefore, FM X9740 has a larger amount of seed surface area per boll than DP 491, 2524 mm2 and 2476 mm2 respectively. The larger seed surface area and higher number of fibers per seed of FM X9740 create more fiber per boll relative to DP 491 even with lower lint percent. This finding indicates a selection method using seed surface area per boll and fiber per boll could be effective for increasing lint yield. The IPS from each F2 population verified several negative and positive relationships that exist between fiber quality, within-boll components and lint percent. The most notable is the negative correlation of burr weight and lint percent, and the generally negative correlation of fiber length and lint percent. There was also a highly significant correlation (R=0.8564) between F2 individual plant data and corresponding F2:4 lines. Standard yield performance testing beyond the three-year study identified at least one line from the study with combination of within-boll yield components, lint percent and yield sufficient for commercial potential.