Evaluation of Reciprocal Relation Between Single and Bundle Fiber Strength of Egyptian Cotton Grades

The four commercial Egyptian cotton varieties (Gossypium barbadense L); Extra-G 92, Extra-G 96, Super-G 97, and Giza 98 were collected from Egyptian gin mills through 2025 season. All cotton varieties were graded into three studied grades, namely; Fully Good (FG), Good (G), and Fully Good Fair (FGF). The study was carried out in Cotton Grading Department, Cotton Research Institute (CRI), Agricultural Research Center (ARC), Egypt. Using two different instruments: Fiber Classifying System (FCS); module Fibrotest for measuring bundle strength, and Fanyuan tester for measuring single fiber strength with presence of elongation at break, work to break and force to break for the two instruments. In single fiber strength for 45, 50 and 55 fiber numbers. There were highly statistically differences for all previous cotton properties. It was an obvious trend of the highest values for single fiber properties compared to bundle fiber in strength and elongation. On the contrary, the highest values of work to break and force to break in bundle fiber strength compared to single fibers measurements. Single fiber strength of 50 fiber numbers showed more stable values than others. All measures of association were more than 90% for coefficient of determination and effect sizes criteria. Practically using Fibrotest for measuring cotton bundle fiber strength is relatively quickly unlike Fanyuan tester according to saving time and efforts unlike a single fiber tester. Knowing the difference between the bundle fiber strength and the single fiber strength helps in predicting yarn strength and the expected level of quality.