scholarly journals Genetic Resistance to Scab Disease in Pecan

HortScience ◽  
1994 ◽  
Vol 29 (9) ◽  
pp. 1078-1080 ◽  
Author(s):  
Tommy E. Thompson ◽  
L.J. Grauke
Keyword(s):  
Gene Action ◽  
Agricultural Research ◽  
Genetic Resistance ◽  
Heritability Estimate ◽  
Carya Illinoinensis ◽  
Additive Gene Action ◽  
Additive Gene ◽  
Agricultural Research Service ◽  
The U.S ◽  
Research Service

Thirty-six cultivars and 948 seedlings from 15 controlled crosses in the U.S. Dept. of Agriculture-Agricultural Research Service pecan [Carya illinoinensis (Wangenh.) K. Koch] breeding program at Brownwood, Texas, were rated for susceptibility to nut scab [Cladosporium caryigenum (Ell. et Lang.) Gottwald] to determine heritability of this trait. Differences between parents and progenies, and within progenies, were highly significant. Within most families, a complete range of resistance reactions were evident, from fully susceptible to fully resistant. Heritability of resistance was determined by regressing individual progeny values on female, male, and midparent values, with the midparent heritability estimate being the highest (0.54). This moderate level of additive gene action and the identification of superior parents in this study will contribute to the efficiency of breeding resistant cultivars.

scholarly journals Chromosome Numbers of Rubus Cultivars at the National Clonal Germplasm Repository

HortScience ◽  
1995 ◽  
Vol 30 (7) ◽  
pp. 1453-1456 ◽  
Author(s):  
Maxine M. Thompson
Keyword(s):  
Chromosome Numbers ◽  
Agricultural Research ◽  
Basic Number ◽  
Agricultural Research Service ◽  
The U.S ◽  
Research Service

Chromosome numbers were counted for 90 Rubus cultivars and selections maintained at the U.S. Dept. of Agriculture, Agricultural Research Service, National Clonal Germplasm Repository, Corvallis, Ore. To my knowledge, 37 of the counts are new, including five that are corrections of previously published counts, 30 that are confirmations of numbers that were previously published but assumed from their parentage rather than actually counted, and 23 that are confirmations of previous counts. The basic number was 7, and 2n numbers ranged from 2x to 14x, including odd-ploids and aneuploids.

scholarly journals Pecan Nut and Kernel Traits Are Related to Shelling Efficiency

HortScience ◽  
2003 ◽  
Vol 38 (4) ◽  
pp. 586-590 ◽  
Author(s):  
T.E. Thompson ◽  
L.J. Grauke
Keyword(s):  
Evaluation System ◽  
Selection Pressure ◽  
Performance Test ◽  
Agricultural Research ◽  
Carya Illinoinensis ◽  
Kernel Color ◽  
The World ◽  
Time Required ◽  
Agricultural Research Service ◽  
The U.S

The U.S. Dept. of Agriculture, Agricultural Research Service conducts the largest and oldest pecan [Carya illinoinensis (Wangenh.) K. Koch] breeding program in the world. This program evaluates thousands of nut and kernel samples each year using a standard nut and kernel evaluation system developed and refined for more than 70 years. This report relates the effectiveness of these evaluations to commercial shelling efficiency by direct comparison of these data to commercially shelled samples from the same clone performance test. Visual ratings of shelled kernel samples (1-5, with 1 = best) were correlated with time required to hand clean kernel samples (r = 0.55). As percent kernel increased, visual ratings of shelled kernels improved (decreased) (r = -0.73). More intact halves were recovered from shelled samples with the best (lowest) visual ratings (r = -0.67). Conversely, fewer pieces of any size were present in samples with the best visual ratings. Visual ratings improved as nut density decreased (r = 0.33). Samples with the lightest kernel color also had the best visual ratings (r = 0.38). These data show that the standard U.S. Dept. of Agriculture pecan nut and kernel evaluation system needs to be refined by modifying selection pressure placed on various standard evaluation traits.

scholarly journals Self-fertility Evaluations of Northern-adapted Rabbiteye Blueberry Hybrids

HortScience ◽  
2012 ◽  
Vol 47 (12) ◽  
pp. 1837-1842 ◽  
Author(s):  
Mark K. Ehlenfeldt ◽  
Matthew Kramer
Keyword(s):  
Fruit Set ◽  
Seed Set ◽  
Agricultural Research ◽  
Highbush Blueberry ◽  
Department Of Agriculture ◽  
Cross Pollination ◽  
Pollen Mixture ◽  
Agricultural Research Service ◽  
The U.S ◽  
Research Service

Rabbiteye blueberry hybrids that the U.S. Department of Agriculture, Agricultural Research Service (USDA-ARS) program has bred for northern adaptation are combinations of 6x V. ashei Reade, 6x V. constablaei Gray, 4x V. corymbosum L., and 2x V. darrowii Camp germplasm at the hexaploid level and are generally composed of 50% or greater V. ashei (rabbiteye) germplasm. Four northern-adapted rabbiteye (NRE) selections (US 1043, US 1045, US 1056, US 1057), four rabbiteye standards (‘Brightwell’, ‘Climax’, ‘Tifblue’, ‘Woodard’), two rabbiteye × V. constablaei derivatives (‘Little Giant’, ‘Snowflake’), and two highbush standards (‘Duke’, ‘Bluecrop’) were pollinated under greenhouse conditions with either self-pollen or a multicultivar, bulk-pollen mixture (appropriate to ploidy level and species) to determine the relative requirements for cross-pollination among NRE selections. Fruit set, berry weight, and seed set were subsequently evaluated. The results suggest that NRE selections, in general, exhibit cross-pollination needs intermediate to the parent types such that: rabbiteye > northern rabbiteye > highbush (i.e., rabbiteye has the lowest self-fertility and the greatest need for cross-pollination). Considerable variation existed among the NRE selections tested, which suggests that it might be possible to select clones with good levels of self-fertility, potentially equivalent to that of highbush blueberry.

scholarly journals Chromosome Numbers of Rubus Species at the National Clonal Germplasm Repository

HortScience ◽  
1995 ◽  
Vol 30 (7) ◽  
pp. 1447-1452 ◽  
Author(s):  
Maxine M. Thompson
Keyword(s):  
Chromosome Number ◽  
Chromosome Numbers ◽  
Agricultural Research ◽  
Basic Chromosome Number ◽  
Ploidy Levels ◽  
Basic Chromosome ◽  
Rubus Species ◽  
Agricultural Research Service ◽  
The U.S ◽  
Research Service

The U.S. Dept. of Agriculture, Agricultural Research Service, National Clonal Germplasm Repository (NCGR), Corvallis, Ore., maintains Rubus germplasm representing worldwide diversity of the genus. Chromosome numbers were counted for 201 plants representing 124 taxa (species and varieties). There are new reports for 42 taxa, confirmation for 72 previously reported, and 10 counts for plants unidentified to species. The basic chromosome number was seven, and ploidy levels ranged from 2x to 12x.

scholarly journals GGE biplot analysis of Line by tester for seed yield and its attributes in sunflower

2019 ◽  
Vol 14 (4) ◽  
pp. 374-389 ◽  
Author(s):  
M A Ahmed ◽  
Mohamed Ali Abdelsatar ◽  
M A Attia ◽  
A A Abeer
Keyword(s):  
Seed Weight ◽  
Gene Action ◽  
Agricultural Research ◽  
F1 Hybrids ◽  
Research Station ◽  
Gge Biplot ◽  
Additive Gene Action ◽  
Economic Trait ◽  
Additive Gene ◽  
Better Than

Nine genetically diverse sunflower promising lines in their economic trait were crossed using line by tester mating design in 2018 spring season, to estimate per se performance, combining ability, heterosis, gene action and heritability for earliness, yield and its attributes traits. The parents involved four sunflower CMS lines namely L1 (A3), L2 (A5), L3 (A9) and L4 (A13) (called hereafter “Lines” (as female parents) and five sunflower genotypes T1 (RF9), T2 (RF10), T3 (RF11), T4 (RF14) and T5 (RF1) as male parents (called hereafter “Tester”). In 2018 and 2019 summer season, the nine parents along with their 20 F1s seeds were evaluated at Shandaweel Agricultural Research Station, ARC, Sohag Governorate, Egypt using a randomized complete blocks design with three replications. Mean squares due to parents (P), crosses (C), CMS lines (L), RF testers (T), P vs C and L x T were significant for all studied traits. A larger magnitude of non-additive gene action than additive was revealed by greater ratios (GCA/ SCA) than unity for all studied traits (except for days to 50% flowering). A5 and A13 of CMS lines and RF11 and RF14 of RF lines proved to be the best general combiners for seed weight plant-1 and one or more of its attributes traits. Moreover, the best cross combinations A13 x RF11, A13 x RF1 and A5 x RF9 performed better than other developed hybrids in view of seed weight plant-1 and one or more of its attributes, hence these F1 hybrids could further be used on commercial exploitation.

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