Exotic Germplasm Introgression Effects on Agronomic Traits and Fiber Properties of Upland Cotton
Type of DegreeDissertation
Agronomy and Soils
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Upland cotton (Gossypium hirsutum L.) is an economically important natural fiber crop in the world. Along with fiber, it is also valued for its oil and protein portion of the seed. Upland cotton is facing a risk associated with a narrow genetic base. The utilization of closely related parents and many reselections within elite cultivars has led to a narrow genetic base. Cotton cultivars with increased genetic diversity can offer plasticity to be able to respond to stressful environments. Our research is focused on the objective of determining the effect of exotic germplasm on agronomic traits and fiber properties of adapted cotton cultivars. Two plant introductions were systematically crossed with four cultivars to derive five groups of lines with various levels of exotic introgression. Experimental materials were tested in a randomized complete block design and analyzed using statistical analysis software. Results revealed highly significant effects due to population, exotic percentage, and population × exotic percentage interactions for all the agronomic and fiber traits except for boll number. An increase in exotic percentage significantly lowered agronomic and fiber properties, however the magnitude of effect varied with populations and exotic percentage levels. Among agronomic traits seed cotton yield, lint seed-1, lint percentage and lint yield were the most affected, whereas days to first flower, bolls plant-1, boll size, seeds boll-1 and lodging were least affected with an increase in exotic percentage. In most populations an increase in exotic percentage did not show any significant difference up to 25 percent exotic germplasm introgression for all the agronomic traits except for lint mass seed-1. Among fiber properties, micronaire was the most affected trait, whereas fiber elongation and short fiber content were the least affected traits with an increase in exotic introgression. In almost all cases where the exotic parent was better or equal to the performance of adapted cultivars, an increase in exotic percentage up to 25 percent did not show a significant difference in fiber properties, which suggests that using exotic parents which are similar or better in fiber properties could expand genetic base of adapted cultivars without altering fiber properties.