الفهرس 
Yield and yield componentsOnly 14 pages are availabe for public view
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Abstract
The present study was carried out in the agronomy Department Faculty of Agriculture, Kafr El-Sheikh, Tanta University. The field experiments were conducted during the 1997 and 1998 growing seasons, in the Agricultural Research farms at the Agricultural Research Station, Salcha and the Agricultural Research station, El-Serw, Agriculture esear&C enter, MALR, Egypt. The present investigation was designed to study the relative magnitudes of the variability and stability parameters for earliness, yield and yield components and fiber properties traits among 14 Egyptian cotton genotypes grown at two locations i.e., Sakha and Damitta in two years (1997 and 1998) under four treatments i.e., two planting dates and two phosphorus fertilization levels. The cotton genotypes were nine Egyptian varieties i.e., Giza 45, Giza 70 Giza 75, Giza 77, Giza 80, Giza 83, Giza 85, Giza 86 and Giza 89 and five strains ofthese varieties propagated with farmer’s for few years i.e. Giza 70193, Giza 75/93, Giza 77193, Giza 85/93 and Giza 86/93 were grown in a randomized complete block design with three replications in each of the 16 environments. Data was collected on : 1- Earliness measurements: - First fruiting node number. - Days to first flower. - Earliness index. 2- Environment exhibited highly significant effects on all traits. However, location effects were insignificant for earliness characters, cotton yield, yield components except for seed index, number of bolls/m2, lint percentage and lint index and fiber properties except micronaire reading and fiber strength gltex. Years effect was significant to highly significant for earliness characters, yield and yield components except nu~nber of bolls/m2, lint percentage and fiber properties except for micronare reading and fiber length. Treatments effect was significant to highly significant for earliness and yield and yield components except for seed index, boll weight, number of seedslboll, lint percentage and lint index, while the effect was insignificant for all fiber propertiesindicating that the macro-environmemts had more effects than the micro-environments on fiber properties. 3- The first order interaction genotype x year was highly significant for earliness characters except for days to first flower, that was insignificant for yield and yield components except for seed index, boll weight and cotton yield that was significant and significant for fiber properties except for fiber strength and elongation. 4- The genotype x location interaction was insignificant for all traits except for first fruiting node, lint percentage, seed cotton yield and micronaire reading. 5- The genotype x treatment interaction was insignificant for all traits except for first fruiting node. 6- The second order interaction genotype x year x location was insignificant for all traits except for earliness characters, cotton yield and micronaire reading and mostly the interactions of genotype x year x treatment and genotype x location x treatment were insignificant for all traits except days to first flower and inicronaire reading. 7- The genotype x year x location x treatment interaction was highly significant or significant for all traits except for days to first flower, seed index, lint/boll, rnicronaire reading and elong&ion, indicating that it is essential to test cotton varieties over a number of different environments in the breeding programs to obtain reliable estimates of relative performance for these varieties. 8- Heritability values ranged from 56.1’ to 93.6% for earliness characters, 71.6 to 97.3% for yield and yield components and 88.7 to 95.1% for fiber properties. Genetic coefficient of variability ranged from 1.5 to 1 1.8% and phenotypic coefficient of variability ranged from 1.9 to 12.5%. The high heritability values and the very close estimates of phenotypic and genotypic variability are indicating that the phenotypic expression of these traits were indicative of their genetic behaviour.