Muthoni,Rachael Kamau2026-02-182026-02-182025http://41.89.96.81:4000/handle/123456789/3533The low-temperature effect has limited the cultivation of sorghum with desirable traits in the highlands. This project was set up to evaluate and characterize sorghum genotypes for reproductive-stage cold tolerance, determine the lipid fractions associated with cold sensitive and cold tolerant sorghum genotypes, and determine and identify lipid fraction associated with cold tolerance in sorghum. Field experiments were conducted at Egerton University, Njoro (0° 22” S:35° 35"E), and Marigat (0°46’ N:35°98’E) while growth chamber, fatty acid extraction and profiling was conducted at Egerton laboratories. Two hundred and fifty (250) genotypes were grown in three replications using Randomized Complete Block Design (RCBD) and evaluated for time taken to 50% heading, plant height, panicle length, panicle weight, panicle harvest index and grain weight. Lipid fraction were extracted using n-hexane a by Soxhlet extraction and methylated into individual Fatty Acid Methyl Esters (FAMES) using Boron trifluoride and separated using Gas Chromatography-Mass Spectrometry (GC-MS). Cluster analysis conducted for the two hundred and fifty genotypes placed sorghum genotypes into three clusters. Genotypes in cluster one remained vegetative, cluster two headed and had productive panicles while those in cluster three had sterile panicles at Egerton site. The genotypes took between 125-205 days to attain heading at Egerton while in Marigat the genotypes took between 49-80 days to heading. The number of tillers was increased for Egerton grown genotypes compared to Marigat. Plant height, panicle length, panicle weight and seed Weight Was reduced at Egerton in comparison to Marigat. Sorghum grown at Egerton had a mean post-harvest index (PHI) of 0.688 and with a range from 0.322-0.916 while the mean in Marigat was 0.750 with a range from 0 to 0.907. A total of fifteen fatty acids both saturated and unsaturated were identified in sorghum genotypes grown under field and growth chamber conditions. The saturated fatty acids included; palmitic acid, lauric acid, myristic acid as well as pentadecanoic acid. Unsaturated fatty acids included oleic, linoleic, linolenic, Cis vaccenic acid, methyl linolenate and arachidonic acid. The Genotypes grown at Marigat showed an increase in the number of saturated fatty acid while, the genotypes that were productive at Egerton had predominantly unsaturated fatty acids. Methyl linolenate was profiled in cold tolerant genotypes grown in Marigat and Egerton, an indication that this fatty acid can be used as a marker for cold and heat tolerance. Basing on characterization and fatty acid data, further research on GBK 000075 and BM 29 is recommended since they exhibit potential use as breeding materials for cold tolerance genotypes for the highland. Fatty acids if quantified can help understand the response mechanisms towards cold tolerance.enPhysiological mechanismReproductive-phaseThesis