الفهرس 
The extra-long staple varietiesOnly 14 pages are availabe for public view
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Abstract
Cotton is t h e most i m p o r t a n t c r o p i n Egypt. The g e n e t i c s t u d i e s a r e considered a s t h e first base of improvanent f o r t h e commercial v a r i e t i e s and production of new l i n e s . The main objectioe of t h e p r e s e n t study was t o determine heterosis , inbreeding depression , G.C.A. , S.C.A. , d i f f e r e n t t y p e s of gene a c t i o n , h e r i t a b i l i t i e s and gain of s e l e c t i o n o f t w e l v e c o t t o n v a r i e t i e s and t h e i r d i a l l e l c r o s s e s F1 and F2 g e n e r a t i o n s a s well a s t h e i r i n t e r a c t i o n s with t h e change of e n v i r o n n e n t a l cond i t i o n s . The c h a r a c t e r s under study were : 1- Seed c o t t o n y i e l d ( y i e l d ) . 2- Lint percentage (L.P.). 3- Boll weight (B.W.). 4- Number of b o l l s (N.B.). 5- Number of f r u i t i n g branches(N.F.B.). 6- Seed index (S.1.). 7- L i n t index (L.1.). 8- P l a n t h e i g h t (P.H.). 9- Days t o f i r s t flower(Flowering).lO-First sympodium rank number (F.S.R.N.). 11-Fiber s t r e n g t h (Press.). 12- Fiber f i n e n e s s (Mic.). I n 1985 season t h e p a r e n t s and t h e i r F1 were evaluated a t Sakha A g r i c u l t u r a l Research S t a t i o n i n f o u r experiments using a randomized coinplete block design each , with t h r e e r e p l i c a t e s under two l e v e l s of n i t r o g e n and two types of n i t r o g e n a p p l i c a t i o n . Exp. 1 : 40 kg N/fad. a s 30 kg N + 10 kg N top ,dressing (NIT1). Exp. 2 : 40 kg N/fad. a s 30 kg N top d r e s s i n g + 10 kg N spray(N T ). 1 2 Exp. 4 : 80 kg N/fed. 2s 60 kg N top dressi.ng + 20 kg N sprey(N2T2). I n 1986 season t h e sane experinents were repeated t o
e v a l u a t e t h e p a r e n t s , F 1 and F 2 g e n e r a t i o n s . The v a r i a t i o n s avong c r o s s e s were f u r t h e r p a r t i t i o n e d i n t o t h e general and s p e c i f i c conbining a b i l i t y co” ” " ~ " ” ”ponents according t o Griffingls method 2 model 1 (1956). Also g e n e t i c a n a l y s i s were conputed accordng t o Sinks and Hayman (1953) and Hayman (1954) . The r e s u l t s obtained could be summarized a s f o l l o w s : A- E f f e c t of enviromental c o n d i t i o n s : 1- In both seasons , e n t r i e s were s i g n i f i c a n t l y d i f f e r e n t fro;n each o t h e r f o r t h e twelve s t u d i e d t r a i t s i n t h e f o u r enviromental c o n d i t i o n s i n e i t h e r F1 and F2 generations. 2- The average performance of t h e f o u r enviromental c o n d i t i o n s v a r i e d s i g n i f i c a n t l y from each o t h e r i n a l l t r a i t s except B.W. , P.H. and Press. t r a i t s ” 3- The d i f f e r e n c e s between t h e average performance o f t h e two n i t r o g e n l e v e l s (N) over t h e two a p p l i c a t i o n methods and between t h e two methods (T) over t h e two n i t r o g e n l e v e l s were s i g n i f i c a n t i n 9 out of 12 and 5 out of 12 t r a i t s , r e s p e c t i v e l y . 4- Yield and most of its important-components were not i n f l u e n c e d t h e n i t r o g e n a p p l i c a t i o n methods i n high l e v e l of n i t r o g e n but y i e l d a s exavple i n c r e a s e d by t h e mixed a p p l i c a t i o n ( s o i l + spray) r e l a t i v e t o only s o i l a p p l i c a t i o n i n t h e low l e v e l (40 kg N/fad.)