Author: William Larry AlexanderPublisher:
ISBN:
Category :
Languages : en
Pages : 86
Book Description
A Genetic Study of Yield Components in Three Populations of Winter Wheat (Triticum Aestivum L. Em Thell)
Author: William Larry AlexanderPublisher:
ISBN:
Category :
Languages : en
Pages : 86
Book Description
Compensating Effects and Gene Action Estimates for the Components of Grain Yield in Winter Wheat (Triticum Aestivum, L. Em Thell)
Author: Michel Abi-AntounPublisher:
ISBN:
Category : Wheat
Languages : en
Pages : 228
Book Description
Five winter wheat cultivars and their diallel crosses were evaluated for plant height, harvest index, deading-maturity duration, the components of yield, (spikes per plant, spikelets per spike, kernel weight and kernels per spikelet)and total plant yield. Two diverse locations, Moro, a dryland site (250 mm annually) located in central Oregon and the Hyslop Agronomy Farm, a high rainfall site (over 1000 mm annually) located in the Willamette Valley, were utilized for one and two cropping seasons, respectively. Three rates of seeding were used as main plots in a split-plot design that was replicated four times. A modified blend method of seeding was used to simulate solid seeding conditions. Experimental seeds were planted 30.5 centimeters apart within the row over a filler cultivar in equally spaced (30.5 centimeters) rows. The data were analyzed by analysis of variance, Griffing's diallel analysis (Method 4, Model 1), correlation, path-coefficient analysis and by parent progeny regression. The correlation between grain yield, its components, harvest index, maturity-duration and plant height was dependent on the particula. r environment of the test. The re waspoorcorrelationbetween yield, tiller number and seed size under all the conditions of these studies. Negative associations between the components of yield indicated the sequential compensatory behavior of these characters under all environments. It would be very hard to select for large grain and short stature wheat because of the positive correlation between plant height and seed size within this population. The low correlations of yield with tiller number and seed size were mainly caused by indirect negative effects through one or more of the other yield components. Harvest index, maturity-duration and plant height had very small direct or indirect influences on grain yield. It was concluded that maximum yield would be obtained from a plant type which produces enough tillers to cover a particular unit of field area with large, fertile spikes, having medium to large kernels and semi-dwarf stature. No significant differences existed between parents and single crosses in the expression of the yield components. Nevertheless, hybrids outyielded their parents in grain yield and demonstrated that heterosis for complex traits was a consequence of multiplicative relationships among the components of these traits. Significant interactions between the genotypes and locations, seeding rates and years were observed in the expression of all characters studied. These interactions indicated that using data from non-competitive conditions to assess performance under competitive conditions could not be justified. Also, limiting the number of testing sites may lead to unsound generalizations and erroneous recommendations regarding gene action estimates of yield and the components of grain yield and three associated characters. Under non-competitive conditions, estimates of the additive type of gene action were more significant and contributed larger effects than the non-additive type for all traits. As competition increased at higher seeding rates, the effects of specific combining ability became more important in the expression of yield, number of spikes, spikelets per spike, and plant height. Heritability estimates confirmed these results except for yield. Of the agronomic characters, harvest index, maturity-duration and plant height, only harvest index showed some promise as a selection criterion under noncompetitive conditions. A breeding procedure utilizing the component approach consisted of selecting early generations under spaced planting with emphasis on avoiding extreme values in any of the components of yield. The balanced combinations of the components of yield should be tested under solid seeding conditions.
Thirty Years of Testing Winter Wheats, Triticum Aestivum L. Em Thell., in the Western Wheat Region: Interstation Correlations of Grain Yield with Vari
Author: F. H. McNealPublisher: Forgotten Books
ISBN: 9780260389077
Category : Business & Economics
Languages : en
Pages : 20
Book Description
Excerpt from Thirty Years of Testing Winter Wheats, Triticum Aestivum L. Em Thell., In the Western Wheat Region: Interstation Correlations of Grain Yield With Varietal Comparisons The State experiment stations of Idaho, Oregon, Utah, and Washington cooperated in growing the first regional winter wheat nurs ery in 1931, and workers in California and Montana have also contributed information to this program at various times. The Western Regional wheat-testing Program has been continued since 1931. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.
Genetic and Molecular Analysis of Grain Yield and Its Components in Wheat B(Triticum Aestivum L.em.Thell)
Author: Satender YadavEvaluation of Three Methods of Selection in Relation to Yield and Yield Stability in Winter Wheat (Triticum Aestivum Vill., Host)
Author: Terd CharoenwatanaPublisher:
ISBN:
Category : Wheat
Languages : en
Pages : 152
Book Description
The effectiveness of early generation selection for yield and yield stability and the possible identification of superior parental combinations were studied in winter wheat populations representing different levels of genetic diversity. Experimental material for evaluating yield stability consisted of nine bulk and seven modified bulk populations derived from nine parental combinations which represented the F, F9, and F10 generations. The F9 and F10 generations of nine bulk, nine modified bulk and two modified pedigree populations along with the respective parental populations were studied to determine the relationship of yield to genetic diversity. Linear regression of the mean yield of individual entries on the mean yield of all entries for each year was used to describe yield stability. Grain yield differences among populations and crosses were analyzed by a functional analysis of variance. The modified bulk populations were found to be superior to their respective parents in yield and to the bulk populations in yield and yield stability. The modified pedigree populations had the highest yield of all populations measured. It was concluded that populations with high genetic diversity not only do not produce the highest yield but may not provide the greatest stability of yield. Selection for grain yield in the F4 generation was effective in identifying superior segregates. It was also possible to develop populations which had more yield stability. The highest yielding progeny were obtained from crosses between the medium yielding parents rather than between the highest yielding parents. This suggested that parental performance was of limited value in predicting the yielding ability of their resulting progeny. Therefore, selection for suitable parental combinations could not be based on their individual performance in the present study. It appeared that genetic factors for adaptability are as important as the level of genetic diversity in determining yield stability. A breeding system that allows the breeder to identify and incorporate genetic factors for adaptability and still maintain some genetic diversity in a new variety is suggested. Such a breeding system would prolong the length of time a variety could remain in commercial production and would allow such a variety to be grown over a more extensive range of environments.
Performance of Cultivars, Hybrids and Composites of Winter Wheat (Triticum Aestivum L. Em Thell) Grown at Three Locations
Author: Ruben P. VergesPublisher:
ISBN:
Category : Winter wheat
Languages : en
Pages : 170
Book Description
The objective of this study was to compare three genetically different groups of winter wheat for their grain yield. Experimental material consisted of parental lines grown in pure stands, hybrids, and 1:1 mixtures of the parental combinations. Three sites were employed to evaluate possible interactions between the different groups across locations. Phenotypic correlations among selected agronomic traits and grain yield within each group along with the expression of heterosis and heterobeltiosis in the hybrids were studied. Results of this investigation support the general conclusion reached by other investigators that hybrids and composites are not consistently superior to the best conventional cultivars of wheat for grain yield. However, at the Moro site, with the greater environmental stresses, some hybrids and composites appeared to yield more than the parental lines grown in pure stands. At Pendleton, the best environment for yield expression, the hybrids and conventional cultivars did not differ for grain yield. At this location, the best hybrids and one composite did significantly outyield the commercial cultivars Stephens, Malcolm and Hill, but not four advanced parental selections when grown in pure stands. Low to moderate values of heterosis and heterobeltiosis for grain yield were found. The degree of expression being affected by the specific growing site. Plant height and the number of kernels per spike showed relatively higher values for heterosis and heterobeltiosis over locations when compared to the other traits. Phenotypic correlations suggested that a breeding program to develop hybrid wheat should combine high number of kernels per spike with high kernel weight. The positive correlation between grain yield and plant height indicated that increases in grain yield could be obtained by increasing plant height if lodging did not present a problem.
Studies of Yield and Yield Components in Hybrid Winter Wheat (Triticum Aestivum L.)
Author: Don Jae MaengQuantitative Trait Loci Mapping of Yield, Its Related Traits, and Spike Morphology Factors in Winter Wheat (Triticum Aestivum L. )
Author: Robert Christopher GaynorPublisher:
ISBN:
Category : Factor analysis
Languages : en
Pages : 170
Book Description
Increasing grain yield in wheat (Triticum aestivum L.) is a challenging task, because yield is a complex trait controlled by many genes and highly influenced by environmental factors. The genetic control of yield components and other traits associated with yield may be less complex and thus more manageable for breeding. This study seeks to identify quantitative trait loci (QTLs) for these traits. Two new genetic linkage maps were constructed from recombinant inbred lines (RILs) derived from crosses between the Oregon soft white winter wheat variety Tubbs and a Western European hard red winter wheat variety, Einstein. A third linkage map was constructed from RILs from a cross with Tubbs and a Western European experimental hard red winter wheat line. A combination of Diversity Arrays Technology (DArT), Simple Sequence Repeat (SSR), orw5, and B1 markers were used to construct genetic linkage maps. Two replications of the RIL populations were grown in yield trial sized plots at Corvallis, OR and Pendleton, OR in 2009. The RILs were evaluated for grain yield, spikes per m2, fertile spikelets per spike, sterile spikelets per spike, seeds per spike, seeds per fertile spikelet, average seed weight, growing degree days (GDD) to flowering, GDD to physiological maturity, GDD of grain fill, plant height, test weight, and percent grain protein. Composite interval mapping (CIM) detected 146 QTLs for these traits spread across all chromosomes except for 6D. Thirty six percent of all of the QTLs detected were in close proximity to four loci: Rht-B1, Rht-D1, B1, and Xgwm372. The use of factor analysis to aid in QTL mapping for correlated traits related to spike morphology was explored. Quantitative trait loci mapping of factor scores for these traits potentially showed an increase in statistical power to detect QTLs and a decrease in the probability of type I error over mapping the traits individually.
Nature of Inheritance, Genotype-environment Interaction and Association of Selected Agronomic Characters in Crosses of Winter X Spring Wheats (Triticum Aestivum L. Em Thell)
Author: P. BrajcichPublisher:
ISBN:
Category : Wheat
Languages : en
Pages : 300
Book Description
This investigation was motivated by the apparent increase in genetic variability resulting from the systematic combining of gene pools represented by winter and spring types of wheats. It was the objective of this study to provide information regarding the nature of this genetic variability for nine agronomic characters in populations resulting from winter x spring crosses. Evaluations were made for: 1) the amount of total genetic variability; 2) the nature of the gene action making up this genetic variability using parent-progeny regression and combining ability analysis and 3) possible direct and indirect associations for traits which influence grain yield. Experimental populations which involved parents, Fl, F2 and backcross generations were grown at two locations where a spring and a winter environment could be utilized. At the winter site, the research was evaluated over a two year period. When the two experimental sites were compared, greater genetic diversity was observed at the spring site for maturity date, plant height, tillers per plant, kernel weight and grain yield. At the winter site, heading date, grain filling period, harvest index and kernels per spike were found to have more total genetic variation. From the expected mean square values, it would appear that the winter parents contributed more to the total genetic variation for most traits measured at both locations. A large genotype-location interaction was also noted suggesting that estimates of gene action and selection for adapted plant types can be done only at the specific winter or spring site. A large portion of the total genetic variation controlling the traits measured was due to additive gene action. However, at the winter site there was also a large influence of non-additive gene action associated with heading date, plant height, harvest index, tillers per plant, kernel weight, kernels per spike and grain yield. Of special interest was that at the winter site the most promising parental combinations could be predicted based on the general combining ability effects of the individual cultivars for each trait studied. Such data were not available for the spring site. Consistent and high correlations were observed between tillers per plant, kernels per spike and, to a lesser extent, kernel weight and grain yield at the winter location. Some negative associations were observed at the spring location between these traits and grain yield suggesting that yield component compensations were involved in the final expression of grain yield. The other characters measured did not reflect significant correlations with yield. When the correlation values were considered in terms of direct and indirect effects for specific traits, a large direct effect was noted for the three components and grain yield. The other traits exhibited small or no direct effects on grain yield but did have a slight influence on grain yield through tillers per plant, kernels per spike or kernel weight.
Author: Sada Ram Verma