Download or read book Compensating Effects and Gene Action Estimates for the Components of Grain Yield in Winter Wheat Triticum Aestivum L Em Thell written by Michel Abi-Antoun and published by . This book was released on 1977 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book O S U Theses and Dissertations 1970 1977 written by Oregon State University and published by . This book was released on 1980 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Plant Breeding Abstracts written by and published by . This book was released on 1980 with total page 1282 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dissertation Abstracts International written by and published by . This book was released on 1984 with total page 508 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Bangladesh Journal of Agriculture written by and published by . This book was released on 1986 with total page 1682 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book American Doctoral Dissertations written by and published by . This book was released on 1983 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Genetic Study of Yield Components in Three Populations of Winter Wheat Triticum Aestivum L Em Thell written by William Larry Alexander and published by . This book was released on 1976 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Combining Ability and Associations of Agronomic Traits Involving Three Sources of Dwarfism in Wheat Triticum Aestivum L Em Thell written by Jose Luis Maya de Leon and published by . This book was released on 1974 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Agronomy News written by and published by . This book was released on 1977 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sept.-Oct. issue includes list of theses and dissertations for U.S. and Canadian graduate degrees granted in crop science, soil science, and agronomic science during the previous academic year.

Download or read book Response of Winter Wheat Triticum Aestivum L Em Thell to Nitrogen and Chloride Fertilization in the Presence of Take all Root Rot Gaeumannomyces Graminis Var Tritici Walker written by Mohamed El Hadi Maatougui and published by . This book was released on 1984 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: Response from nitrogen and chloride fertilization was measured in field experiments on winter wheat (Triticum aestivum L. Em. Thell. var. 'Stephens' and 'Yamhill') grown in western Oregon in an environment with a range of susceptibility to take-all root rot (Gaumannomyces graminis var. tritici Walker). Cropping sequences and expected disease severity considered in the study were: first year wheat after clover (low risk of severe take-all root rot: Nixon I experiment), second year wheat with high disease infection in the previous crop (high risk of severe take-all root rot: Keyt II experiment), second year wheat with low disease infection in the previous crop (moderate risk of severe take-all root rot: Nixon II and Coon experiment), third year wheat (high risk of severe take-all root rot: Jones experiment), fifth year wheat (high risk of severe take-all root rot: Keyt II experiment), and eighteenth year wheat (take-all decline established: the pathogen is present in the soil but does not cause damage, Evers experiment). Nitrogen treatments were applied at 0, 67, 134, and 202 kg/ha in all experiments where wheat followed wheat and at 0, 45, 90, and 134 kg/ha in the experiment where wheat followed clover. Chloride treatments were applied at 0, 45, and 90 kg/ha in all experiments and a rate of 134 kg C1/ha was also used on the Jones experiment. Nitrogen was predominantly supplied from urea while ammonium chloride supplied chloride and ammonium sulfate supplied the crop requirement for sulfur (about 20 kg/ha). Fertilizers were top-dressed in split application with chloride and sulfur containing fertilizers applied first (February) and urea applied later (March) in all experiments but those conducted in the Nixon farm where a single fertilizer was applied in March. Crop response was measured through the effects of N and c1 treatments on dry matter production, plant nitrogen content, plant nitrogen uptake and plant percent nitrogen recovery, as well as grain yield, yield components, grain nitrogen content, grain protein content, grain nitrogen uptake, and grain percent nitrogen recovery. The results of the study strongly indicated that take-all root rot was only a problem in the Jones, Keyt I, and Keyt II experiments and was most severe in third year wheat (Jones experiment). This also was the only experiment with significant (p = 0.05) response from rates of 202 kg N/ha. Nitrogen fertilization was the main factor that greatly influenced the levels of the variables studied while chloride fertilization generally did not have a significant (p = 0.05) influence. 134 kg N/ha was generally the rate accounting for the best levels of each variable studied in all experiments except in the Jones experiment as precised earlier. Crop response was also affected by a relatively long 'dry' period (April 20th to June 20th), particularly in the experiment where take-all root rot was a problem. Levels of the variables studied accounted for by the optimum rates of N were consistently higher in the experiments where take-all root rot was not a problem than where it was a problem by the following amounts: dry matter yields-17%, plant nitrogen contents-18%, plant nitrogen uptake levels-30%, plant nitrogen recoveries-28%, grain yields-22%, grain nitrogen contents-only 4%, grain protein contents-only 2%, grain nitrogen uptake levels-26%, grain nitrogen recoveries-18%, and spikes/m2-24%.

Download or read book The Influence of Plant Densities on Gene Action Estimates and Associations in Seven Winter Wheat Parents and Their F2 Progeny written by Surinder Kumar Saini and published by . This book was released on 1968 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: The F2 progeny from a diallel cross involving seven winter wheat parents along with the parents were grown at the Hyslop Agronomy Farm near Corvallis, Oregon to determine the influence of three plant densities on gene action estimates for yield and its primary components. The plant densities were designed to provide different levels of competitions involving solid, six and 12 inch spacing within the rows with one foot spacing between the rows. Gene action estimates were obtained by the combining ability analysis as well as narrow sense heritability estimates. In addition, path-coefficient analysis was utilized to investigate the direct and indirect associations of the primary components of yield under different stresses of competition resulting from the changes in population densities. The morphological characters measured were 1) total yield per plant, 2) kernel weight 3) number of kernels per spikelet, 4) number of spikelets per spike, 5) tiller number and 6) plant height. A small additive gene action for yield was noted in the six inch spacing while additive gene action effects could not be detected in the 12 inch and solid plantings. Yield being a complex trait seems to be affected by the environmental changes resulting from different plant densities. Consistent general combining ability estimates were observed for kernel weight and plant height in all the plant densities, indicating a small genotype-environment interaction. In the spaced plantings additive gene action estimates were obtained for tiller number and spikelets per spike while there was no evidence of additive gene effects in the solid planting. No additive gene action was noted for kernels per spikelet in the 12 inch planting while six inch and solid plantings revealed considerable genetic variability. These results would suggest that the genotypes are susceptible to environmental fluctuations for the traits tiller number, spikelets per spike and kernels per spikelet. The correlation coefficients reveal that in spaced plantings tiller number, spikelets per spike and kernels per spikelet are significantly and positively related to yield. In the solid seeding only spikelets per spike was significantly associated to yield. When the four variables were considered in terms of their associations with yield it was observed in the F2 that in spaced plantings all the four components of yield have direct positive influence on yield. In the solid seedings however, spikelets per spike and kernels per spikelet had high positive direct effects on yield while tiller number and kernel weight showed a negative direct influence on yield. The data revealed that spikelets per spike and kernels per spikelet are the most important traits contributing towards yield. However, the results obtained with correlation coefficients indicate that a negative association existed between these two traits as well as between kernels per spikelet and tiller number suggesting the possible existence of a biological limitation between these components of yield. The results indicate that a breeding program with emphasis on the selection of plants in competitive conditions in the early generations may make the selection work more efficient. Moreover, increases in yield which considers each of the components separately or in combination of two or more would offer the most promise. By this procedure the breeder would take advantage of the large amount of additive genetic variances associated with each of the components and at the same time take into consideration any biological limitations which may exist.

Download or read book Duration and Rate of the Grain Filling Period and Subsequent Grain Yield in Crosses Between Facultative and Winter Wheat Cultivars Triticum Aestivum L Em Thell written by Beiquan Mou and published by . This book was released on 1985 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: Concerns about the genetic control and environmental influence of various stages of development including the grain filling period, and the relationship between early maturity and grain yield prompted this study. The experimental material consisted of two facultative and two winter wheat cultivars. A dial!el cross, excluding reciprocals, was also developed to provide an Fl generation. Information was collected for 14 traits and subjected to statistical analyses. Genetic differences among varieties were found for time of heading, flowering and physiological maturity, duration and rate of the grain filling period, grain yield and yield components. The facultative types, AI Feng 2 and Selection CB 83-52, showed earlier heading, flowering and physiological maturity, longer lag period (period between heading and flowering), and longer duration and lower rate of grain filling, resulting in lower grain yield. The winter cultivars, Stephens and Yamhill Dwarf, in contrast had later heading, flowering and maturity, shorter lag period, and shorter duration and higher rate of grain filling, giving higher grain yield. For the developmental stages after heading, larger differences were observed in the lag period while differences in duration of grain filling period were relatively small among the cultivars. Depending on the specific Fl population, there was a tendency toward dominance for early heading, a range from no to complete dominance for early flowering and no dominance for physiological maturity. Long duration and fast rate of grain filling were generally dominant. Grain yield was positively associated with the number of days to heading, flowering and physiological maturity. Also positive associations of grain yield were obtained with tiller number, kernel weight, grain weight per spike, biological yield and rate of grain filling. Negative associations of grain yield were noted with lag period and duration of grain filling period. No clear associations between physiological maturity and the yield components were found. Grain filling duration showed no association with yield components while grain filling rate exhibited positive association with tiller number and kernel weight. There was negative association between duration and rate of grain filling period. According to heading responses from different planting dates, Stephens and Yamhill Dwarf had high sensitivity while Selection CB 83- 52 and AI Feng 2 showed low sensitivity to vernalization. Genotype X environment interaction was observed with each cultivar responding differently for several traits depending on the planting dates.

Download or read book Comprehensive Dissertation Index written by and published by . This book was released on 1984 with total page 904 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Interrelation of the Components of Grain Yield in a Cross Between Dwarf and Semidwarf Wheat Triticum Aestivum L Cultivars written by Luis E. Medina and published by . This book was released on 1988 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: Parents and progeny populations from a cross of 'Stephens'x 'Tibet dwarf' were grown in a spaced-planted experiment to obtain information concerning the nature of inheritance and possible associations between grain yield and the components of yield. Agronomic traits measured on an individual plant basis were: heading date, days to maturity, grain filling period, plant height, biological yield, number of spikes per plant, total length of spikes, spikelets per spike, kernels per spikelet, total kernel number, grain yield, kernel weight, harvest index, and chaff percentage. The nature of gene action was estimated for each trait by comparing broad and narrow sense heritability estimates. Possible associations among traits were determined by phenotypic and genotypic correlations as well as by path coefficient analysis. This latter analysis was based on the genotypic correlations of total grain yield with five other traits. Narrow sense heritability estimates were high for kernel weight, spikelets per spike, heading date, kernels per spikelet, chaff percentage, and total kernel number. Intermediate estimates were found for plant grain yield, spikes per plant, plant height, harvest index, days to maturity and total length of spikes. A low estimate was realized for biological yield. Narrow sense heritability values were higher than broad sense heritability for spikelets per spike, kernel weight, chaff percentage and heading date. These inflated estimates are attributed to sampling errors and/or uneven environmental influence on the various generations. Path coefficient analyses suggested that among the yield components, the number of kernels per spikelet was most closely associated with grain yield, followed by the number of spikelets per plant, the number of spikelets per spike and kernel weight. Low direct associations with grain yield were found for both harvest index and plant height. A moderately high association between harvest index and grain yield was the result of an indirect association via spikelets per spike. As suggested by both narrow sense heritability estimates and path coefficient analysis, selection for number of kernels per spikelet among the F2 populations of the cross of Stephens and Tibet dwarf would result in increased grain yield in succeeding generations. Path coefficient analysis indicated that the direct relation between grain yield and plant height was low, suggesting that short, high yielding plants could be selected within segregating populations resulting from this cross.

Download or read book Indian Science Abstracts written by and published by . This book was released on 1994 with total page 924 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effect of Plant Growth Regulators on Morphological Characteristics Grain Yield and Yield Components of Winter Wheat triticum Aestivum L C v Norstar written by P. M. S. Bandara and published by . This book was released on 1987 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Effect of Growth Regulators on Winter Survival Lodging and Yield of Norstar Winter Wheat written by P. M. S. Bandara and published by . This book was released on 1987* with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: