Browsing by Author "Apak, R."

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Adaptation and Stability Analysis in the Selected Lines of Tir Wheat
(Pakistan Botanical Soc, 2006) Ulker, M.; Sonmez, F.; Ciftci, V.; Yilmaz, N.; Apak, R.
Genotype and environment (G x E) interactions are of major concern to plant breeders in breeding cultivars. The objective of this study was to determine the stability of grain yield in 12 wheat genotypes. Eleven lines selected from Tir wheat population (Triticum aestivum) were used in the study. The experiment was conducted in Van, Ercis, and Adilcevaz located in the eastern part of Turkey in 1997-98 and 1998-99. Two stability parameters were obtained as linear regression coefficient (b) of an entry mean on the average of all entries and deviation from regression (s(2)d), then stability was tested with the hypotheses b = 1.0 and s(2)d = 0. The results indicated that there were significant differences and interactions among genotypes, locations and years. The regression coefficient (b) values of the 11 genotypes used in this study ranged from 0.46 to 1.73; deviation from regression ranged from 69.9 to 2896.7. According to estimates of the two stability parameters, none of the genotypes were stable for grain yield. However, based on the linear regression coefficient and average grain yield, line 2 (Adilcevaz-40/1) and 11 (Van-Edremit/1) appeared to be promising because their yields were above the average in all of the environmental conditions of this study.
The Relationships Among Grain Yield and Some Yield Components in Tir Wheat
(TUBITAK, 1999) Sönmez, F.; Ülker, M.; Yilmaz, N.; Ege, H.; Bürün, B.; Apak, R.
Field experiments were conducted in 1994 and 1995 in Van in order to study the relationships between grain yield and yield componets, and the interrelationships among these yield components and other characteristics in Tir wheat. In this research, heading duration, the number of spikes per m2, grain filling period, the number of grain per spike, grain weight, and grain yield were studied. Direct and indirect effects of the yield components (the number of spikes per m2. the number of grain per spike, and grain weight) on grain yield were found by Path coefficient analysis. Direct and indirect effects of other characteristics on these components were also determined. The direct effects, obtained in the Path coefficient analysis, indicated that grain yield depended mainly upon spike number per m2 and secondly upon the grain number per spike. Grain weight showed less influence. On the other hand, duration had a highly negative influence on the grain filling period. At theend of the research, it has been found possible to increase grain yield when spike number per m2 used as a selection criterion in Tir wheat.