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Author: Mohammad M. El-Ajlouni Publisher: ISBN: Category : Durum wheat Languages : en Pages : 71
Book Description
"Inheritance mechanisms for fifteen plant characters of wheat (Triticum durum) Desf. were studied in the F2, F3, and F4 generations in four crosses derived from four parents grown in Jubeiha, University of Jordan Campus during 1984 and 1985 seasons. The parents are Hourani, Mexicali 75, Yamuna, and Njoro 227. Phenotypic associations between grain yield and its components were high, while the morpho-physiological traits have poor positive association with grain yield and its components. Estimates of broad sense heritability indicated low to high values for all traits except number of spikelets/spike, spike length, and flag leaf area which showed low to medium values. High heritability coupled with high genetic advance for some characters such as total seed number/plant, plant height, and main spike seed number and weight indicated that selection for these traits will be valuable. Some characters showed high values for additive gene action in some crosses which mean that selection for these characters could be practiced in early generation. In Hourani x Mexicali 75 cross, heritability values were high in most of the characters. This cross also showed strong association between grain yield and other characters."--Page iv.
Author: Mohammad M. El-Ajlouni Publisher: ISBN: Category : Durum wheat Languages : en Pages : 71
Book Description
"Inheritance mechanisms for fifteen plant characters of wheat (Triticum durum) Desf. were studied in the F2, F3, and F4 generations in four crosses derived from four parents grown in Jubeiha, University of Jordan Campus during 1984 and 1985 seasons. The parents are Hourani, Mexicali 75, Yamuna, and Njoro 227. Phenotypic associations between grain yield and its components were high, while the morpho-physiological traits have poor positive association with grain yield and its components. Estimates of broad sense heritability indicated low to high values for all traits except number of spikelets/spike, spike length, and flag leaf area which showed low to medium values. High heritability coupled with high genetic advance for some characters such as total seed number/plant, plant height, and main spike seed number and weight indicated that selection for these traits will be valuable. Some characters showed high values for additive gene action in some crosses which mean that selection for these characters could be practiced in early generation. In Hourani x Mexicali 75 cross, heritability values were high in most of the characters. This cross also showed strong association between grain yield and other characters."--Page iv.
Author: Ahmet Ertug Firat Publisher: ISBN: Category : Wheat Languages : en Pages : 280
Book Description
Parental and segregating populations derived from four winter x spring wheat crosses were investigated to obtain information concerning the inheritance and association of earliness, grain yield and yieldrelated traits. Feasibility of selecting in early generations for these characteristics was also evaluated. Four winter wheat cultivars (Hyslop, Yamhill, Bezostaia 1, and Sprague) and one spring wheat cultivar (Inia 66) were chosen on the basis of their relative maturity and contrasting agronomic characteristics. Parents, F1 s, F2' s, and reciprocal backcrosses to both parents were planted in the fall in a space-planted randomized complete block design. The two environmentally diverse locations selected were the Hyslop Agronomy Farm, Corvallis, Oregon (1000 mm of rainfall) and Sherman Experimental Station, Moro, Oregon (250 mm of rainfall). The effectiveness of early generation selection for the measured characteristics was evaluated by growing F3 lines identified as the earliest 1% and the highest yielding 1% of F2 individuals in each cross. These were grown along with the parents, F1s, BC1 s, BC2 s and F2' s under space-planted conditions at Hyslop Agronomy Farm. A study with the same populations was conducted by vernalizing and planting in the spring to gain further information on earliness. Analyses of variance were conducted for all characteristics measured. Frequency distributions for days to heading of F1, F2, backcross generations and parents were examined. From the data collected, estimates of F 1 -midparent deviations, degree of dominance, heritability in the narrow sense and genetic advance under selection were determined for each cross. The data were further analyzed by parent-progeny regression, correlation and path-coefficient analyses, polynomial and multiple regressions. Partially dominant major genes, varying in number between one to five depending on the particular cross, appeared to influence heading date. Modifying factors also seemed to affect the date of heading. The gene action involved in the inheritance of earliness was primarily additive indicating that selection for earliness would be effective as early as the F2 generation under both high and low rainfall conditions. Estimates of additive and nonadditive gene action suggested both were equally important in determining the yield components. Higher heritability estimates for the components of yield indicated that there was more genetic variability associated with the yield components than yield per se. Occurrence of additive genetic variation by location interaction implied that selection should be practiced simultaneously under different environments if wide adaptability of potential lines is desired. Since pronounced additive effect by year interactions occurred for the yield components, delayed selection for these traits may not be productive. Positive correlations were obtained between yield and the number of days to heading when all generations were combined. However, in the F2 generations, it appeared possible to select for the desired earliness with high yields as indicated by the low association between these two traits. The path-coefficient analyses suggested that tiller number had the highest direct effect on grain yield. However, because of a negative association between tiller number and kernel weight, selection pressures would have to be balanced between these two components. In most cases, linear relationships existed between grain yield and seven measured traits, respectively. The result of regression analyses also showed that grain yield may be described best as a linear function of its components.
Author: Jose Luis Maya de Leon Publisher: ISBN: Category : Wheat Languages : en Pages : 232
Book Description
Three genetically different dwarf cultivars of spring wheat were evaluated as potential sources of short stature to use in a wheat improvement program. The study involved a five parent diallel cross which included a semidwarf, a standard height and three dwarf cultivars. The genetic sources of dwarfism included a Norma 10 derivative named Vicam 71, a derived line from Tom Thumb called Tordo, and Olesen dwarf. Experimental material consisted of parental lines, F1, F2, and both backcrosses to the parents space planted in a randomized block design. The agronomic characters measured on an individual plant basis were: (1) plant height, (2) days to heading, (3) number of tillers, (4) number of spikelets per spike, (5) head length, (6) days to maturity, (7) grain yield, (8) harvest index, (9) kernel weight, (10) number of kernels per spikelet, (11) rachis internode length, (12) grain filling period and, (13) head grain weight. Estimates of gene action were determined by heterosis, heterobeltiosis, broad and narrow sense heritabilities and combining ability analyses. Associations among traits were estimated by phenotypic, environmental, and genotypic correlations as well as path-coefficient analysis for grain yield and eight of the variables. There were significant differences among the parental lines, their crosses, and generations for all traits measured. Either partial dominance for tallness or no dominance was manifested for those crosses involving the dwarf cultivars Vicam 71 and Olesen. Tordo, when crossed to taller wheats showed dominance for short stature. All three genetic sources of dwarfism and their resulting progenies manifested desirable agronomic characteristics. Vicam 71 was a good parent in terms of grain yield and number of tillers per plant. Tordo was the best source for increasing the number of spikelets per spike, kernel weight and head grain weight. Olesen was a good progenitor for increasing number of kernels per spikelet. All three dwarf cultivars displayed some advantage(s) over the other two and all could be used to breed short statured wheats with a possibility of success. Plant height did not appear to have a direct effect on plant grain yield in any of the 10 crosses. With the exception of number of tillers per plant and grain yield, a major proportion of the phenotypic variability observed for all characters studied was due to genetic factors. A large portion of the total genetic variability associated with days to heading, maturity, height, rachis internode, spikelet number, kernels per spikelet, kernel weight, and harvest index was mainly a result of additive gene action. Both additive and non-additive genetic effects were involved in the expression of grain filling period and head weight. The nonadditive portion of the genetic variance associated with tiller number and grain yield per plant was relatively large when compared with the additive portion. Therefore, selection for increased expression of tillers and yield should be delayed until the F4 or later generations where a large degree of homozygosity has been obtained. The genetic correlations for individual crosses indicated that only a few of the traits studied were associated in the same manner in most or all the 10 hybridizations. High positive genetic correlations were found between plant grain yield vs tiller number and kernels per spikelet, tiller number vs days to maturity, kernels per spikelet vs head grain weight, plant height vs head weight, and head length vs rachis internode length. High negative genetic correlations were found between kernel weight vs days to maturity, plant height vs harvest index, and days to heading vs grain filling period. Most correlations among agronomic traits were different in value and/or sign from one cross to another suggesting different gene associations in the parental cultivars. Genetic correlations between components of yield showed this type of inconsistency. Therefore, grain yield could be increased by a combined increase of more than one component of yield without compensatory oscillation among them because tiller number, spikelet number, kernels per spikelet and kernel weight were often not correlated between one another and sometimes were positively correlated. Path-coefficients analysis indicated that number of tiller per plant had a high direct effect on grain yield in all crosses. With the exception of two crosses, indirect effects of this trait were negligible. In the latter two crosses tiller number had a high negative indirect effect on plant grain yield via head grain weight. Kernels per spikelet and kernel weight had no direct effects on grain yield but their indirect effects via head weight were positive and significant. Large amounts of additive gene action were observed in the expression of plant height. This trait was also highly negatively correlated with harvest index; therefore, phenotypic selection for restricted plant height would be useful in obtaining lines with high grain to straw ratios. In general, crosses that showed high specific combining ability effects involved parents with low general combining ability. However, there were some exceptions to this rule. Crosses of high x high and high x low general combiners presented high specific combining ability effects, suggesting that some additive gene action may be involved in the superior performance of these combinations. Also the F 2 generation did not differ from the F1 in assessing general cornbining ability. A wheat breeder should be aware of those genetic associations between agronomic traits that could be used to select superior cultivars. However, the genetic correlations in this study suggested that each cross represented a different set of gene associations depending upon the parents involved. If some progress is to be made in using the genetic variability available in the crop, the breeder should not try to select exactly the same type of plant from every cross. Every hybridization is potentially a source of better lines if they are well planned and the reasons they were made are remembered during selection. It is very important to realize what are the contributions of each parental line in a cross and what are the most important trait associations present in each parent. Superior rural genetic variability existing in the crop.
Author: V Younger Publisher: Elsevier ISBN: 0323150020 Category : Nature Languages : en Pages : 447
Book Description
The Biology and Utilization of Grasses reviews current knowledge about grass biology, and it highlights the important role of grasses in human existence. It discusses many fundamental aspects of grass biology, including evolution and genetics, morphology, physiology, and ecology, with emphasis on the relationship of these basic concepts to the use of grasses for forage, turf, and rangelands. Comprised of 28 chapters, this volume begins with an overview of the evolution and genetics of the grass family, followed by a discussion on practical grass-breeding problems. The reader is also introduced to vegetative growth and development of seedlings and mature plants; the ecological aspects of grasses; soils and mineral nutrition in relation to grass growth; the effects of defoliation (moving or grazing); carbohydrate reserves; physiology of flowering; and grass seed production and culture treatments. Other chapters consider the role of polyploidy in the evolution and distribution of grasses; selection and breeding of grasses for forage and other uses; seedling vigor and seedling establishment; environmental modification for seedling establishment; the microclimate of grass communities; effects on turf grass of cultural practices in relation to microclimate; and competition within the grass community. This book will be of benefit to plant breeders, ecologists, botanists, and biologists.
Author: Mohammad M. El-Ajlouni
Author: Mohammad M. El-Ajlouni
Author: 
Author: 
Author: Ahmet Ertug Firat
Author: 
Author: Jose Luis Maya de Leon
Author: John E. Woolston
Author: American Society of Agronomy
Author: 
Author: V Younger