QUALITATIVE AND QUANTITATIVE ANALYSIS OF GRADES IN LONG AND EXTRA-LONG STAPLE VARIETIES OF EGYPTIAN COTTON

Abstract

This investigation aimed to study the relationship of descriptive grades to actual staple and cotton yarn qualities estimated by the devices and also to estimate the contribution of each of the characteristics technological estimation of the grades in the Egyptian cotton.

The materials used in this study were four commercial varieties of Egyptian cotton; two (Giza 86 and Giza 90) belonging to the long staple class and the others (Giza 88 and Giza 92) belonging to the extra-long staple category. Within each variety, nine lint cotton grades namely: Fully Good (FG), Good/Fully Good (G/FG), Good (G), Fully Good Fair/Good (FGF/G), Fully Good Fair (FGF), Good Fair/ Fully Good Fair (GF/FGF), Good Fair (GF), Fully Fair/Good Fair (FF/GF) and Fully Fair (FF) were used. Thus, Fully Good (FG) is the top quality grade and the others are progressively lower; i.e. Fully Fair (FF) is the lowest grade. Fiber properties were measured by using the Cotton Classifying System Version-5 instrument (CCS-V5).

Results collected for the following characteristics were: reflectance degree (Rd %), yellowness degree (+b), trash%, dust%, fiber fragments%, total trash%, No. of neps, micronaire value, fiber maturity ratio%, linear density, upper half mean length (mm), short fiber index%, mean fiber length (mm), fiber uniformity index%, fiber strength (g/tex) and fiber elongation%.

Statistical procedures used in this study were done according to completely randomized design as outlined by steel et al (1997). The phenotypic correlation coefficients for all possible pairs of the sixteen characters were determined according to Dewey and Lu (1959). Partitioning correlation coefficients into direct and indirect effects as well as the relative importance (RI%) at phenotypic level was made by determining path coefficients using the method given also by Dewey and Lu (1959).