scholarly journals Two-Stage Selection in Slash Pine Produces Good Gains in Fusiform Rust Resistance

1996 ◽  
Vol 20 (3) ◽  
pp. 143-147 ◽  
Author(s):  
Earl R. Sluder
Keyword(s):  
Combining Ability ◽  
Rust Resistance ◽  
First Generation ◽  
Diallel Cross ◽  
Slash Pine ◽  
Breeding Value ◽  
Rust Disease ◽  
Fusiform Rust ◽  
Improvement Programs ◽  
Half Diallel

Abstract The best 6 of 21 progeny-tested first-generation slash pine selections were crossed in a half diallel to study inheritance patterns of their superior fusiform rust resistance (5 trees) and height (1 tree). Their six first-test progenies were duplicated and included in the study. These two groups of progenies, along with two commercial check lots, were planted on an Upper Coastal Plain and a Flatwoods site in Georgia. At age 10 yr, the 15 progenies in the half diallel averaged 23% rust-infected compared with 54% for the check lots. First-test progenies averaged 30% infected. For percentage infection, the six parents differed in general combining ability (GCA) (0.01 > P > 0.001) on both test sites and in specific combining ability (0.05 > P > 0.01) on one site. GCA variation for height was significant (0.05 > P > 0.01) on one site. The parent selected for height had the highest breeding value for height at age 10 yr. These results show that resistance to the fusiform rust disease, a serious problem in management of the species, can be improved in slash pine. These 6 parents and their 15 progenies in the half-diallel cross are a good source of rust resistance genes for use in slash pine improvement programs. South. J. Appl. For. 20(3):143-147.

Fusiform Rust in Crosses Among Resistant and Susceptible Loblolly and Slash Pines

1989 ◽  
Vol 13 (4) ◽  
pp. 174-177 ◽  
Author(s):  
Earl R. Sluder
Keyword(s):  
Pinus Taeda ◽  
Loblolly Pine ◽  
Diallel Cross ◽  
Slash Pine ◽  
Family Selection ◽  
Fusiform Rust ◽  
Loblolly Pines ◽  
Progeny Tests ◽  
Pinus Taeda L ◽  
Half Diallel

Abstract Progenies from a half-diallel cross among six loblolly pines (Pinus taeda L.) and another among six slash pines (P. elliottii Engelm. var. elliottii) were field-tested in central Georgia for fusiform-rust (Cronartium quercuum [Berk.] Miyabe ex Shirai f. sp. fusiforme) resistance. Threeof each set of six parents were rated resistant (R) and three susceptible (S) to the fungus relative to check lots in previous progeny tests. For both species, relative susceptibility of the three types of progenies at age 5 years was R x R < R x S < S x S. The R x R and R x S progeniesin slash pine had considerably less infection than did the same types of progenies in loblolly pines. All S x S progenies were heavily infected. Heritability estimates for percentage infection and average galls per tree indicated that in these progenies, family selection should be based onpercentage infection for slash pine and galls per tree for loblolly pine. South. J. Appl. For. 13(4):174-177.

scholarly journals Combining ability and heterosis on yield and its component traits in maize (Zea mays L.)

2016 ◽  
Vol 41 (3) ◽  
pp. 565-577 ◽  
Author(s):  
MZA Talukder ◽  
ANM S Karim ◽  
S Ahmed ◽  
M Amiruzzaman
Keyword(s):  
Combining Ability ◽  
Diallel Cross ◽  
Kernel Weight ◽  
Early Maturity ◽  
Ecological Zones ◽  
Component Traits ◽  
Additive Gene ◽  
Positive Heterosis ◽  
Half Diallel ◽  
Kernel Yield

Combining ability and heterosis were studied in a 7×7 half diallel cross in maize for grain yield and yield contributing characters. Significant general and specific combining ability variances were observed for all the characters studied. The significant estimates of GCA and SCA variances suggested the importance of both additive and non-additive gene actions for the expression studied traits. In these studies, variances due to SCA were higher than GCA for all charactesr, which revealed the predominance of non additive gene action (dominance and epistasis) for controlling these traits. Parents P1 and P4 were excellent general combiner for days to tasseling and silking while P1 and P5 for early maturity. P4 for short height and, P4 and P7 for higher thousand kernel weight. The parents P4 and P6 having good combining abilities for yield. Heterosis estimation was carried out using two commercial varieties NK40 and 900MG. When standard commercial check NK40 was used, the percent heterosis for kernel yield varied from -51.39 to 12.53%. Among the 21 F1s, 3crosses exhibited significant positive heterosis for kernel yield. The highest heterosis was exhibited by the cross P4×P6 (12.43%), P6×P7 (10.89%) and P2×P3 (9.87%) respectively. Compared with 900MG as check, the percent heterosis for kernel yield varied from -53.73 to 7.01%. Among the 21 F1s, none of the crosses exhibited significant positive heterosis for kernel yield. The highest heterosis were exhibited by the crosses P4×P6 (7.01%), P6 x P7 (5.55%) and P2×P3 (4.57%). The crosses showed significant positive SCA values could be used for variety development after verifying them across the agro-ecological zones of Bangladesh.Bangladesh J. Agril. Res. 41(3): 565-577, September 2016

scholarly journals General and specific combining abilities in a lulo diallel cross (Solanum quitoense Lam.)

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
David Duarte-Alvarado ◽  
Tulio César Lagos-Burbano ◽  
Liz K. Lagos-Santander ◽  
Carlos-Andrés Benavides-Cardona
Keyword(s):  
Combining Ability ◽  
Nutritional Value ◽  
Diallel Cross ◽  
Polar Axis ◽  
Fruit Weight ◽  
Cold Climate ◽  
Breeding Programs ◽  
Single Cross ◽  
Improvement Programs ◽  
Flowering Onset

Lulo (Solanum quitoense) is a promising agro-industry fruit tree, not only because of its nutritional value, taste, and appearance but also because it provides an alternative production system in mild and moderately cold climate zones. Lulo crop yield and production in the Department of Nariño (Colombia) has decreased in recent years when compared to other producing regions in Colombia. Therefore, the objective of this study was to estimate the effects of the general combining ability (GCA) and the specific combining ability (SCA) in a diallel cross of 10 promising parents in four growing regions of the Department of Nariño for use in breeding programs. A total of 45 hybrid combinations were obtained and assessed with Griffing method 4. The following variables were assessed: days to flowering onset (DFO), number of clusters per branch (NCB), fruit weight (FW), polar axis (PA) of the fruit, and yield (Y). The analysis of variance showed statistical differences for most variables in response to single-cross hybrid effects and locations, except for NCB and Y. Moreover, significant differences were found for the interactions between the GCA and SCA and the hybrids and locations, respectively, meaning that environment must be considered when selecting parents with specific adaptability. The effects of the GCA and SCA promoted higher positive values for the FW and Y in parents 4, 6, and 8 and their combinations. Therefore, these parental genotypes are promising for lulo genetic improvement programs since their additive effects and genetic dominance favor fruit weight and yield.

Predicted Genetic Gains from one Generation of Slash Pine Tree Improvement

1989 ◽  
Vol 13 (1) ◽  
pp. 51-56 ◽  
Author(s):  
G. R. Hodge ◽  
T. L. White ◽  
G. L. Powell ◽  
S. M. De Souza
Keyword(s):  
First Generation ◽  
Pinus Elliottii ◽  
Tree Improvement ◽  
Slash Pine ◽  
Growth And Yield ◽  
Yield Model ◽  
Individual Tree ◽  
Fusiform Rust ◽  
Pine Tree ◽  
Growth And Yield Model

Abstract Gains over unimproved seed for progeny from first generation--un-rogued, first generation--rogued, and one and one-half generation orchards of slash pine (Pinus elliottii var. elliottii) for individual tree volume at 15 years are predicted to be 10%, 15%, and 19%, respectively. Rustinfection of orchard progeny on sites where unimproved material incurs 50% infection are predicted to be 49%, 41%, and 35% for the three orchard types. Using a growth and yield model that incorporates fusiform rust, gains in individual tree volume and increased rust resistance were combinedto estimate effects on per acre yields. Percent volume per acre gains are predicted to be 7.0%, 13.2%, and 18.0% for the three orchard types. Collection and deployment of the most rust resistant seed to high rust hazard sites raises the gain on these sites and becomes increasingly beneficialas the rust hazard increases. South. J. Appl. For. 13(1): 51-56.

GENOTYPE × ENVIRONMENT INTERACTIONS IN SMOOTH BROMEGRASS. I. YIELD

1979 ◽  
Vol 21 (1) ◽  
pp. 57-63 ◽  
Author(s):  
Wai-Koon Tan ◽  
Geok-Yong Tan ◽  
P. D. Walton
Keyword(s):  
Genetic Variation ◽  
Analysis Of Variance ◽  
Combining Ability ◽  
Significant Variation ◽  
Diallel Cross ◽  
General Combining Ability ◽  
Bromus Inermis ◽  
Smooth Bromegrass ◽  
Combining Ability Analysis ◽  
Half Diallel

Twenty-one progenies and the parents of a 7 × 7 half diallel cross of smooth bromegrass (Bromus inermis Leyss.) were evaluated at four locations in Alberta in each of two years, for genetic variation and genetic by environment interactions in the expression of their yield potentials. Years, locations and their interactions were highly significant in the combined analysis of variance. Combining ability analysis revealed that general combining ability (GCA) and specific combining ability (SCA) were both important in the expression of yield, including spring, fall and annual yield, whereas GCA was more important than SCA for yield per area. Although the genotype × environment interactions were all highly significant, variation accounted for by combining ability effects was generally higher than the interaction effects of GCA and SCA respectively, with environments. High average GCA effects for spring, fall and annual yield were demonstrated for the clones UA5, UA9 and B42. These together with the high average SCA effects suggested that the three clones could be included in a synthetic to develop high yielding cultivars. The results suggested that recurrent selections involving multi-location and multi-year testing seems necessary in breeding for high yielding bromegrass cultivars in Alberta.

Monoterpene composition and fusiform rust resistance in slash and loblolly pines

1995 ◽  
Vol 25 (2) ◽  
pp. 193-197 ◽  
Author(s):  
M. Michelozzi ◽  
T.L. White ◽  
A.E. Squillace ◽  
W.J. Lowe
Keyword(s):  
Loblolly Pine ◽  
Rust Resistance ◽  
Slash Pine ◽  
Cortical Tissue ◽  
Fusiform Rust ◽  
Breeding Values ◽  
Loblolly Pines ◽  
Monoterpene Composition

Monoterpene composition of cortical tissue was analyzed in slash pine (Pinuselliottii Engelm. var. elliottii) and loblolly pine (Pinustaeda L.) clones with known breeding values for fusiform rust resistance. Trees having a relatively high content of β-phellandrene tend to be more resistant than trees with a low β-phellandrene content. Such results confirm previous data and suggest the utilization of β-phellandrene content as an aid in selecting relatively rust resistant slash and loblolly pines.

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