Investigation of Multivariable Analysis and Phenotypic Diversity in Various BarleyGenotypes Across Different Temperature Conditions

High temperature is one of most domineering abiotic stress influences that border barley production.Herein, three different field experiments at three different locations were carried out at Sakha, Malawi and New-valley research stations, to identify the response of ten barley genotypes to different temperatures degrees using phenotypic diversity and, multivariable analysis during two consecutive seasons 2020/2021 and 2021/2022 under three different temperatures degrees.Heat stress index (HI) activated a reduction in all traits ranged from lowest average reduction in plant height (PH) by ( 5.43 and 20.37%) to highest average reduction in No. of tires m 2 TM by (14.49 and 40.83 %) under Malawi (T2) and New Valley (T3) locations respectively as camper by Sakha, also high temperature enhancement all the genotypes to quicken flowering and days to maturity by average (7.24 and 8.35 %) under New Valley.Days to heading HD and days to maturity MD exhibited a strong and negative significant relationship with all studied traits.Loading principal component analysis PCA accounted 86.1% of the total variability, which PCA2 clarified 24.2 % of the total variability influenced by HD and MD which placed in the left side (negative).The scatter plot from the PCA analysis shows that the Egyptian barley genotypes-Giza 137, Giza 138, line 5, line 1, and line 3 are distinctly separated from the other genotypes.They cluster on the right side of PCA1, forming a significant group that indicates their potential for heat tolerance.Meanwhile, a cluster heatmap reveals two primary groupings among the ten barley genotypes.Giza 137, Giza 138, line 5, line 1, and line 3 are closely related, likely due to their heat stress resilience, whereas line 2 and line 8 group together, displaying a sensitivity to heat.This differentiation allows us to leverage these genotypes in our future barley breeding programs aimed at enhancing heat tolerance and increasing yield, marking a crucial step toward developing new, robust genotypes