SELECTION OF EARLY GENOTYPES BY BIOMETRICAL AND MOLECULAR TOOLS TO IMPROVE FIBER YIELD IN UPLAND COTTON (Gossypium hirsutum L.)

Abstract

Cotton (Gossypium hirsutum L.) is a major fiber crop but contributing minimum to our GDP. However, productivity remains limited due to long crop duration (6-7 months) and low yield of cultivated varieties. Therefore, this study aimed to identify early-boll picking with high quality fiber yield potential genotypes through integrated biometrical and molecular approaches. Three experiments were conducted from July 2021 to December 2023 at Cotton Research, Training and Seed Multiplication Farm, Sadarpur, Dinajpur started with 100 and ended to 12 upland cotton genotypes comprising released varieties, elite breeding lines, local cultivars, a mutant variety, and advanced lines. In the first experiment, genotypes JA-11/L, BC-0025, BC-0033, BC-0027, RA-2, and BC-0024 showed superior yield and early performance. High heritability coupled with high genetic advance was shown by boll number, boll weight, and seed cotton yield. Correlation and path analyses identified sympodial branches, bolls per plant, and single boll weight as key yield determinants. Cluster and principal component analyses grouped the genotypes into eight distinct clusters, with the first five principal components explaining 73.09% of total variation. The second experiment evaluated 45 selected genotypes for earliness and productivity. Genotypes RA-2, BC-0027, BC-0491, BC 0510, and BC-0512 combined early maturity with high yield and outperformed standard checks. The third experiment assessed 12 promising genotypes for morphological, fiber quality traits and molecular profiling. Significant variation was detected in plant height, flowering time, bolls per plant, fiber yield, and earliness index. Fiber quality parameters like upper half mean length, strength, micronaire, and reflectance varied significantly. The genotype BC-0491 and BC-0510 exhibited superior fiber attributes. Molecular characterization using 20 SSR markers identified nine polymorphic markers generating 26 alleles. Markers MGHES16 and NAU3736 showed high polymorphic information content. STRUCTURE and UPGMA analyses revealed two major genetic clusters, confirming genetic distinctness among the selected genotypes. Overall, integration of morphological, fiber, and molecular analyses identified the genotypes RA-2, BC-0027, BC-0491, BC-0510, and BC-0512 as promising parental lines for developing early maturing, high-yielding cotton varieties with improved fiber quality suitable for Bangladesh.