Maintenance of genetic diversity is an important safeguard against vulnerability to biotic and abiotic stresses. The coefficients of parentage, r, among cultivars computed from known pedigree information can be used as an index of genetic diversity. Because of the emphasis placed on developing barley (Hordeum vulgare L.) cultivars for the malting and brewing industry, it seemed likely that barley may have a narrower gene pool than other crop species where less emphasis has been placed on quality traits. Our objective was to examine the diversity among North American spring barley cultivars and the contribution of major ancestors to the two‐ and six‐rowed barley gene pools using the coefficient of parentage as an index of diversity. Coefficients of parentage were computed for all pairs of 167 spring barley cultivars. Mean r with major ancestors was computed for cultivars categorized by row type and era of release. A cluster analysis, performed on the coefficient of parentage matrix, produced 30 disjoint clusters. The five ancestors with highest mean r with cultivars contributed 45 and 62% of the germplasm to the early and recent two‐rowed cultivars and 52 and 44% of the germplasm pool in the six‐rowed cultivars for the two respective time periods. Mean r within the two‐ and six‐rowed cultivars was 0.11 and 0.10, respectively. Mean r within cultivars increased 180% in the two‐rowed and 36% in the six‐rowed cultivar groups from the early to recent cultivar groups. Cultivar groups formed by the cluster analysis produced mean within‐cluster r values ranging from 0.29 to 0.57. Principal coordinate analysis of the between cluster matrix showed that the two‐ and six‐rowed gene pools are essentially unrelated. Major six‐rowed malting cultivars grouped into two clusters and the major two‐rowed malting cultivars grouped into one cluster. These results show that malting barley cultivars are based on a limited sample of germplasm.
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Registration of 'Rampart' Wheat Rampart, a hard red winter wheat (Triticum aestivum L.) cultivar (Reg. no. CV-845, P1593889) with tolerance to damage caused by wheat stem sawfly (Cephus cinctus Norton), was developed and released by the Montana Agricultural Experiment Station in 1996. Rampart resulted from an FS selection from the cross 'Lew'/'TiberV/'Redwin'. Lew is the source of sawfly resistance (1). Rampart was evaluated as MTS92042 in Montana Preliminary, Intrastate, and Off-Station yield nurseries from 1992 to 1996 and in the Northern Regional Winter Wheat Performance Nursery in 1996. Following selection for stem solidness and uniformity in F? headrows and Fg linerows during 1993 and 1994, 103 linerows were bulked as breeder seed. Rampart will supplement and/or replace 'Vanguard' (2), a sib selection which is currently the only other sawfly-tolerantwinter wheat availableforMontanaproducers. Rampart is a bronze-chaffed cultivar with awned spikes. Kernels are hard, red, and long, with a sloped back, a midsized germ, and a heavy brush. Kernel cheeks are rounded to angular, with an open crease. Coleoptile length of Rampart is very long, averaging 10 to 20 mm longer than the conventional-height cultivars Vanguard, Rocky, and Neeley in replicated growth chamber evaluation (dark) at 20°C for 12 d. Rampart has some field tolerance to wheat streak mosaic virus (WSMV) or its vector, wheat curl mite (Aceria tosichella Keifer), in Montana. Rampart is resistant to prevalent races of stem rust (caused by Puccinia graminis Pers.:Pers.) but susceptible to leaf rust (caused by P. recondita Roberge ex Desmaz.), stripe rust (caused by P. striiformis Westend.), dwarf bunt (caused by Tilletia contraversa Ktthn in Rabenh.), and Russian wheat aphid (Diuraphis noxia Mordvilko). Rampart is medium in maturity, heading about 1 d later than Rocky and 'Judith' but 2 to 3 d earlier than Neeley. Rampart is similar in height to Judith, Neeley, and Vanguard (86 cm, 36 environments), with a tendency to lodge, particularly in high-yield environments. Winterhardiness of Rampart is similar to Vanguard, Rocky, and 'Centurk'. Rampart expresses high levels of stem solidness in most environments, and like other solid-stemmed genotypes, shows lower levels of larval infestation, reduced feeding damage, and less head weight reduction than hollow-stemmed genotypes (3). Additionally, stem solidness reduces the numbers of larvae which cut stems and reach a successful overwintering position (3). Rampart is tolerant to feeding and cutting damage of wheat stem sawfly based on limited yield testing under moderate to heavy sawfly infestations and field-scale observation of resistance to sawfly cutting under heavy sawfly infestations. Grain yield of Rampart is slightly lower than the best hollow-stemmed cultivars in the absence of wheat stem sawfly, but equivalent or superior to most hollow-stemmed cultivars under moderate to heavy sawfly infestations. From 1993 to 1996 (36 location-years), grain yield of Rampart (3931 kg ha~') was 7,5, and 2% lower than pred...
The inbred parental lines in this study were derived from varieties of sunflowers grown for their large edible seed (Helianthus annuus var macrocarpus (DC.) Ckll.) and from the wild type H. annuus ssp. annuus.A classification using the following types was found to be adequate for genetic studies of branching in sunflowers: 0 ‐ no branching, 1 ‐ basally branched, 2 ‐ top branched, 3 ‐ fully branched with a central head, 4 ‐ fully branched without a central head (wild type).Four genes for branching were named in this study: the dominant gene Br2 for top branching; the duplicate dominant genes Br2 and Br3 from the wild type parent; and the recessive genes b2 and b3 which gave a fully branched phenotype only when homozygous for both genes.The single gene Y for green versus yellow growing point color was found to be linked with the gene Br3 for branching with 11.6 ± 1.0% recombination.
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