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The objective of this study was to establish different single or multiple trait selection indices to calculate genetic and economic gains by combining some production, reproduction and udder health traits in a population similar to the overall practical situation in Iran, with and without imposing restrictions on genetic change for some traits. The SelAction software was used to perform the analyses based on selection index theory through a deterministic model. Results indicated that among established indices, the index that showed the highest genetic gain for milk yield did not maximize the total genetic and economic gains. Rather, the index that included all production, reproduction and udder health traits yielded the highest genetic and economic gains. When we placed restriction on the selection indices, the economic gain decreased and the amount of reduction depended on the heritability and the correlation of restricted trait(s) with other traits. Generally, regarding the economic genetic gain per generation, the indices based on records of 200 offspring were 4.819% more efficient than those that used information of 100 offspring. [ABSTRACT FROM AUTHOR]

The genotype × environment (GE) interaction influences genotype selection and recommendations. Consequently, the objectives of genetic improvement should include obtaining genotypes with high potential yield and stability in unpredictable conditions. The GE interaction and genetic improvement for grain yield and yield stability was studied for 11 durum breeding lines, selected from Iran/ICARDA joint program, and compared to current checks (i.e., one durum modern cultivar and two durum and bread wheat landraces). The genotypes were grown in three rainfed research stations, representative of major rainfed durum wheat-growing areas, during 2005-09 cropping seasons in Iran. The additive main effect and multiplicative interaction (AMMI) analysis, genotype plus GE (GGE) biplot analysis, joint regression analysis (JRA) ( b and Sdi), six stability parameters derived from AMMI model, two Kang's parameters [i.e., yield-stability (YSi) statistic and rank-sum], GGE distance (mean performance + stability evaluation), and two adaptability parameters [i.e., TOP (proportion of environments in which a genotype ranked in the top third) and percentage of adaptability (Ad)] were used to analyze GE interaction in rainfed durum multi-environment trials data. The main objectives were to (i) evaluate changes in adaptation and yield stability of the durum breeding lines compared to modern cultivar and landraces (ii) document genetic improvement in grain yield and analyze associated changes in yield stability of breeding lines compared to checks and (iii) to analyze rank correlation among GGE biplot, AMMI analysis and JRA in ranking of genotypes for yield, stability and yield-stability. The results showed that the effects due to environments, genotypes and GE interaction were significant ( P < 0.01), suggesting differential responses of the genotypes and the need for stability analysis. The overall yield was 2,270 kg ha for breeding lines and modern cultivar versus 2,041 kg ha for landraces representing 11.2 % increase in yield. Positive genetic gains for grain yield in warm and moderate locations compared to cold location suggests continuing the evaluation of the breeding material in warm and moderate conditions. According to Spearman's rank correlation analysis, two types of associations were found between the stability parameters: the first type included the AMMI stability parameters and joint regression parameters which were related to static stability and ranked the genotypes in similar fashion, whereas the second type consisted of the rank-sum, YSi, TOP, Ad and GGED which are related to dynamic concept of stability. Rank correlations among statistical methods for: (i) stability ranged between 0.27 and 0.97 ( P < 0.01), was the least between AMMI and GGE biplot, and highest for AMMI and JRA and (ii) yield-stability varied from 0.22 (between GGE and JRA) to 0.44 (between JRA and AMMI). Breeding lines G8 (Stj3//Bcr/Lks4), G10 (Ossl-1/Stj-5) and G12 (modern cultivar) were the best genotypes in terms of both nominal yield and stability, indicating that selecting for improved yield potential may increase yield in a wide range of environments. The increase in adaptation, yield potential and stability of breeding lines has been reached due to gradual accumulation of favorable genes through targeted crosses, robust shuttle breeding and multi-locational testing. [ABSTRACT FROM AUTHOR]

To study the genetic variation, heritability and genetic correlations for seed yield and its components (panicles emergence date, anthesis date, panicle number, plant height, panicle length, 1000-grain weight, seed number and seed weight per panicle, harvest index, seed yield, dry matter (DM) yield and fertility index) in tall fescue (Festuca arundinace Schreb), 20 parents were randomly chosen from a genetically broad-based population, and their respective half-sib families were generated. Clonally propagated parents and their half-sib family seeds were grown as individual spaced plants using a randomized complete block design with two replications in Alborz Research Center, Karaj, Iran, during 2002-2004. The estimates of broad-sense heritability (hb²) were moderate to high for all traits (hb² = 0.46-0.82), except harvest index, seed number and seed weight per panicle. Narrow-sense heritability hn² estimates from analyses of progenies and from regression of half-sib (HS) progenies on parents (hop² for heading date, pollination date, were always high, which suggested that genetic variation in these traits was controlled largely by additive gene action. For seed yield and its components (panicle length, 1000-grain weight and fertility index), the hn² and hop² estimates were moderate, relatively the same values as hb², which suggested that additive genetic variance was the main component controlling of these traits. For panicle number, plant height and DM yield, hn² and hop² estimates were low, whereas hb² estimates were moderate, which suggested that both additive and nonadditive gene effects played an important role in the genetic regulation of these traits. Genetic correlations of panicle emergence and thesis date with both DM and seed yield, were strongly negative. Seed yield was ositively correlated with DM yield in both parents and HS families, whereas DM yield was positively correlated with panicle number and panicle length, and plant height. The genetic correlations between seed yield and plant height, panicle number, panicle length, harvest index, seed weight per panicle and fertility index were, in general, positive and significant. We concluded that there was significant variation and moderate heritability for most traits in the tall fescue populations evaluated to improve seed and herbage yield. Selection should focus on increased DM yield, coupled with fertility index and early flowering. [ABSTRACT FROM AUTHOR]