EFFICACY OF EARLY SELECTION FOR FIRE BLIGHT RESISTANCE AND THE ANALYSIS OF COMBINING ABILITY FOR FIRE BLIGHT RESISTANCE IN SEVERAL PEAR PROGENIES

1990 ◽  
Vol 70 (3) ◽  
pp. 905-913 ◽  
Author(s):  
H. A. QUAMME ◽  
F. KAPPEL ◽  
J. W. HALL

A set of progenies was tested for fire blight resistance by needle inoculation at 3 mo of age in the greenhouse and then 5 yr later in the orchard to determine if the measurements of fire blight resistance made in the greenhouse was correlated with those made in the field. The correlation of fire blight resistance at the two stages of growth was weak or absent on a single plant basis. This indicated a lack of precision in the greenhouse test but genetic gain based on the field measurements appeared to be possible if plants were selected in the greenhouse with less than 19% of blighted shoot length. In another set of progenies, the greenhouse test was observed to delay fruiting, but the delay was not greater than 1 yr. It is proposed that selection for fire blight be carried out at both stages of growth, in the greenhouse as single measurements on young plants and again in the field when repeated measurements can be made. Maximum likelihood estimates of the variance components determined on data that were transformed by arc sine of the square root and corrected for censoring more than 100% blighted shoot indicated a high general combining ability and a low specific combining ability for fire blight resistance. Genetic variance was, therefore, predominantly additive. Combining ability estimate indicated Kieffer was the superior female parent and HW 601 and Old Home were the superior male parents. If this sample of parents is representative, genetic advance for fire blight resistance should be obtained by selecting parents on the basis of phenotypic values.Key words: Pyrus, Erwinia amylovora, general combining ability, specific combining ability

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 821E-821
Author(s):  
Philipp Simon

A six-parent diallel which included carrot inbreds with a range of carotene content from 80 to 490 ppm was evaluated over 2 years. General combining ability accounted for most of the variation observed. Phenotypic mass selection was exercised for high carotene content in three carrot populations. Response to selection continued to be high in one population, HCM, after 11 cycles of selection. In contrast, after three generations of selection, little progress was able to be made in a population derived from primarily Nantes-type open-pollinated cultivars. Realized heritability estimates varied from 15% to 49%. Environment contributed significantly to variation in carotene content.


Helia ◽  
2001 ◽  
Vol 24 (34) ◽  
pp. 1-16 ◽  
Author(s):  
Domenico Laureti ◽  
Andrea Del Gatto

SUMMARYA total of 245 test cross progenies obtained by crossing cytoplasmic male sterile (CMS) lines and restorer (RHA) lines were evaluated in replicated trials in 1995 and 1997. Experiments were carried out in two locations (Osimo, East Central Italy and Budrio, Northern Italy) in 1995, whereas in 1997 trials were conducted only in Osimo. General combining ability (GCA) and specific combining ability (SCA) of the parents was evaluated to identify genotypes suitable to be used as testers for breeding programs and to verify the performance of hybrids. The results obtained in 1995 were used to make test crosses in 1996 to be evaluated in 1997. The GCA and SCA of RHA and CMS lines were nearly always significant for all the studied traits when lines were randomly taken in 1995. When selected testers were used on the basis of the results of the first year, the SCA of new RHA lines and GCA of new CMS lines were not significant for achene yield, but they were for the other traits.The best GCA estimates for RHA were often higher than those of CMS, indicating that selection for RHA could be more useful than for CMS. As expected, GCA was always lower than SCA. CMS and RHA, with high variance among their test crosses for yield and many other traits, could be used as testers. The lack of a tester with high variance in all traits requires more than one tester in evaluating lines. The GCA of a line can change in function of the germplasm with which it is combined.


1966 ◽  
Vol 46 (1) ◽  
pp. 59-67 ◽  
Author(s):  
Eric D. Putt

Heterosis occurred for the eight plant and seed characters studied. It was most frequent for yield of seed and height of plant. Mean squares for general combining ability (gca) and specific combining ability (sca) were significant (P =.01) for all characters. The estimated components for gca were greater than for sca for days to mature, weight per bushel, and percent oil in the seed; less for height and yield of seed; and essentially the same for days to bloom, diameter of head, and weight per 1000 seeds.The yield of seed and percent oil in the seed, for the highest ranking 100 synthetics that could be composed from the 10 lines, was predicted in F6 assuming 50 and 60% outcrossing between F2 and F6. Virtually all values exceeded the mean performance of four check samples of commercial hybrids. Many exceeded the highest rank check for oil content in the seed. Fourteen of the highest ranking 100 synthetics for yield and 30 for oil content consisted of two or three lines. It was concluded that synthetics can be superior to the present hybrids in heterosis and that desirable synthetics can be made from only a few lines.


1969 ◽  
Vol 11 (4) ◽  
pp. 810-822 ◽  
Author(s):  
D. R. Knott ◽  
S. S. Sindagi

Diallel crosses were made among six varieties of hard red spring wheat that differed considerably in yield and other characteristics. The F1 hybrids were tested at two seeding rates and the F2, hybrids at one. Heterosis was not great in either generation and no cross appeared to be promising. General combining ability was much more important than specific combining ability and parental yields gave reasonable predictions of hybrid yields. Yields of hybrids at the two seeding rates were closely correlated.


1999 ◽  
Vol 22 (3) ◽  
pp. 451-456 ◽  
Author(s):  
Cleso Antônio Patto Pacheco ◽  
Cosme Damião Cruz ◽  
Manoel Xavier dos Santos

The objective of the present work was to provide a methodology to study the inheritance of adaptability and stability through the breakdown of Eberhart and Russell regression coefficients and regression deviations in effects due to the mean and additive genetic effects (gi's and gj's) as well as dominance effects (sij's) of Griffing´s methodology, when the diallel is conducted in several environments. It was concluded that the adaptability and stability parameters are determined in the same manner as are genetic effects. So an F1 cross inherits half the general combining ability (GCA) mean effect from each parent, while the effects due to specific combining ability (SCA) are subjected to the same considerations relative to sij's, i.e., they are dependent on specific combinations.


2009 ◽  
Vol 66 (2) ◽  
pp. 204-209 ◽  
Author(s):  
Leonardo Oliveira Medici ◽  
Salete Aparecida Gaziola ◽  
Vanderlei Aparecido Varisi ◽  
José Antonio Carmezini de Paula ◽  
Renato Rodrigues Ferreira ◽  
...  

Six S5 lines of maize, with differences for lysine and oil contents in grains, were used to carry out a complete series of diallelic crosses. The resulting 15 hybrids were grown in a field at two nitrogen levels (10 and 130 kg N ha-1). The general combining ability (GCA) and specific combining ability (SCA) were obtained by using the method 4, model I of Griffing for grain yield, and grain lysine and oil contents. Significant (p < 0.001) interaction was observed between GCA and N levels for grain yield, indicating the selection of different lines for each N level. This interaction was not significant for lysine content, but there were significant effects of GCA for this trait at both N levels (p < 0.1). Significant effects were not observed for GCA or SCA for oil content, however a positive correlation was observed between lysine and oil contents in the hybrids, in the lines and even in the control cultivars. The results indicate the effectiveness of selection for lysine content, irrespective of N level, in the studied non-opaque maize lines, and the possibility of achieving both high lysine and oil content in grains.


Author(s):  
В. В. Ващенко ◽  
О. О. Шевченко

У системі діалельних схрещувань п’яти сортів яч-меню ярого (Донецький 12, Донецький 14, Донецький 15,Прерія, Галактик) установлено особливості генети-чного контролю мінливості ознак: висота рослин,кількість зерен у колосі, маса 1000 зерен у відповід-ності зі співвідношенням варіанс специфічної комбі-наційної здатності (СКЗ) і загальної комбінаційноїздатності (ЗКЗ). Виділено й запропоновано сорти якджерела ознак висота рослин Галактик і Донецький14; кількість зерен у колосі – сорт Прерія; маса 1000зерен – сорт Донецький 15. Виділені зразки з високимі стабільним рівнем комбінаційної здатності запро-поновано використовувати в селекційній роботі. A total of diallel analysis varieties of springbarley Donetskiy 12, Donetskiy 14, Donetskiy 15,Prairie, Galactic set features genetic controlvariability characteristics: plant height, number ofgrains per ear, 1000 grain weight in accordance withthe ratio of variance of specific combining ability(SSI) and general combining ability (ZKZ).Identified and proposed as a source of variety traitsplant height and Donetsk 14, Galactic, the numberof grains per ear sort Prairie, weight of 1000 grainsDonetskiy 15. Samples of high and stable levels ofcombining ability is proposed to use in breedingwork have beeen celected.


2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Jeffrey N. Wilson ◽  
Michael R. Baring ◽  
Mark D. Burow ◽  
William L. Rooney ◽  
Charles E. Simpson

Peanut (Arachis hypogaeaL.) has the potential to become a major source of biodiesel, but for market viability, peanut oil yields must increase. Oil yield in peanut is influenced by many different components, including oil concentration, seed mass, and mean oil produced per seed. All of these traits can potentially be improved through selection as long as there is sufficient genetic variation. To assess the variation for these traits, a diallel mating design was used to estimate general combining ability, specific combining ability, and heritability. General combining ability estimates were significant for oil concentration, weight of 50 sound mature kernels (50 SMK), and mean milligrams oil produced per SMK (OPS). Specific combining ability was significant for oil concentration. Reciprocal effects were detected for OPS. Narrow-sense heritability estimates were very high for oil concentration and 50 SMK and low for OPS. The low OPS heritability estimate was caused by the negative correlation between oil concentration and seed size. Consequently, oil concentration and seed mass alone can be improved through early generation selection, but large segregating populations from high oil crosses will be needed to identify progeny with elevated oil concentrations that maintain acceptable seed sizes.


2012 ◽  
Vol 42 (5) ◽  
pp. 770-776 ◽  
Author(s):  
Lauro José Moreira Guimarães ◽  
Glauco Vieira Miranda ◽  
Rodrigo Oliveira DeLima ◽  
Ciro Maia ◽  
Lucimar Rodrigues de Oliveira ◽  
...  

The objective of this study was to evaluate four maize testers for identification of superior inbreed lines in testcross. The four testers evaluated are cultivars with narrow or wide genetic base (single-cross hybrids and open pollinated varieties) and two kernel types (flint or dent). SynD and SynF testers are open pollinated varieties with dent and flint kernels, respectively, and FSH and DSH testers are single-cross hybrids with flint and dent kernels, respectively. SynD tester showed the biggest genetic variance among the maize inbreed lines in crosses. The effects of general combining ability (GCA) for lines and specific combining ability (SCA) for lines x testers were significant, whereas GCA effects for testers were not significant. SynD and SynF testers identified the largest number of lines with higher GCA. The DSH and FSH testers showed suitable to identify lines with high SCA. It was concluded that SynD and SynF testers are adequate to identify inbreed lines with high GCA effects, and it's possible to identify new lines with high heterotic potential in each one of the four testers.


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