ALBERT

Notizen: Summary A selected group of 42 guayule (Parthenium argentatum Gray) lines were evaluated on the basis of various morphological characteristics and compared to a total population of 234 lines. The objective of this study was to determine the amount of variation that existed both within and among guayule lines over a 2-year period. The parental lines all reproduced apomictically, and as expected, many lines exhibited a high degree of uniformity for every measured character. However, many other lines were extremely variable for varying numbers of characters. This appears to be due to varying degrees and combinations of apomeiosis, thus establishing a long-term source of genetic variation. The high amount of variability existing among and within these guayule lines indicates that significant progress by selection for both rubber percentage and yield is feasible.

Notizen: Abstract Twenty-three Pinus radiata seed orchard clones of the New Zealand “850” series were each control-pollinated with a mix of 10 pollens to produce polycross families. The seed was sown in open nursery beds. Seedlings were potted up at six times of the year and subjected to white advective frosts in controlled-environment rooms, with up to seven frosting runs of variable severities at each time. There were significant differences (p〈 〈0.001) between families in frost injury, such that, although there was statistically significant family × time interaction, some families were consistently more frost resistant (tolerant) than others. No association between frost resistance and growth rate was evident. Individual-tree heritability estimates for frost damage scores were around 0.3 at given times, and 0.20 over all times. Prospective gain in resistance from progeny testing over several seasons of the year, with 2:23 selection, is about 1°C. An additional gain of 0.4°C resistance appears obtainable from 1:90 selection of individuals within pair-crosses in a single frosting run. This additional (within-cross) gain might be increased to around 0.75°C, with the same culling rate but testing one ramet per seedling at each of four times of the year.

Notizen: Summary Simple phenotypic, genotypic and environmental correlation coefficients were calculated from one year's data for nine characters in F1 seedlings of 72 crosses and 18 parents of potato (Solanum tuberosum L.). Crosses were made in a line x tester model having 12 female lines and six male testers. The experiment was designed as a randomized block replicated three times at Kufri, Simla (India) during the 1979–80 crop season. Positive phenotypic and genotypic correlations of 1000-TPS weight were found with total tuber yield, number of leaves on the main shoot, number of shoots per plant and harvest index. The results suggest that 1000-TPS weight could be used when attempting to select for yield and other characters in F1 seedlings.

Notizen: Summary A technique is described which enables potato clones to be screened for resistance to both species of potato cyst nematode (Globodera rostochiensis andG. pallida) and to blight (Phytophthora infestans) in the foliage during the winter and first spring following harvest of seedlings grown from true seed. A container test, used to assess resistance to both species ofGlobodera in a mixed inoculum, is followed by an assessment of resistance to foliage blight, using the same plants in the glasshouse. This screen can be completed in time for duplicate tubers of the resistant clones to be planted for multiplication in the second growing season. The close correlation between results obtained using this system and those predicted from the known inheritance of the characters selected and the gain in efficiency achieved in breeding, are illustrated by examples. In Kartoffelzuchtprogrammen müssen viele Eigenschaften berücksichtigt werden. Die Reihenfolge ihrer Selektion kann grossen Einfluss auf die gesamte Arbeitsleistung haben. Dort wo die Aufspaltung der Nachkommenschaft bedeutsam ist, kann eine frühe Selektion leicht erkennbarer Eigenschaften, wie Resistenz gegenüber Schädlingen und Krankheiten, die Populationsgrösse wirkungsvoll verringern. Dies könnte den starken Selektionsdruck auf Knolleneigenschaften als erste Hauptprüfung in Kartoffelzuchtprogrammen ersetzen. In dieser Arbeit wird eine Technik zur Prüfung auf kombinierte Resistenz gegenüber Kartoffelnematoden und Krautfäule beschrieben, und es werden die Ergebnisse für Nachkommen aus typischen Kreuzungen mitgeteilt (Tabelle 1). Die Nematodenresistenz wurde mit Hilfe eines Gefässtestes ermittelt, bei dem ein Inokulumgemisch aus Larven vonGlobodera rostochiensis undG. pallida verwendet wurde. Dies ergab die in Tabelle 2 dargestellten Befunde und eine Verteilung der Zystenproduktion, wie sie in den Abbildungen 1A und 1B gezeigt wird. Diese Ergebnisse bestätigten, dass die nicht wiederholten Tests Reaktionen ergaben, wie sie von der bekannten Vererbung der Eigenschaften erwartet wurden, und ein Chi-Quadrat-Test (Tabelle 2) ergab bei drei von vier Familien, dass keine Abweichung von den erwarteten Verhältnissen für H1, von dem sich dieG. rostochiensis-Resistenz herleitet, vorlag. Eine vorkommende Abweichung (Tabelle 2, Familie 4) liess sich mit der ungenügenden Unterscheidung der unreifen Zysten von beidenGlobodera-Arten erklären. Bei der Selektion auf Resistenz gegenüber den beiden Arten ist diese Fehlerquelle unbedeutend. Die als nematodenresistent ermittelten Pflanzen wurden in Töpfen bei hoher Luftfeuchtigkeit in einem Polythen-Tunnel in Gewächshaus angezogen und mit einer Zoosporensuspension aus einem Isolatkomplex vonPhythophthora infestans besprüht. Die Anfälligkeit wurde ermittelt, indem die ungefähre Blattfläche der entstehenden nekrotischen Läsionen bewertet wurde. Die Ergebnisse in Tabelle 3 und die Verteilung der resistenten Klone (Abb. 1C) weisen—wie erwartet—auf die polygene Vererbung hin. Bei den angewandten Selektionsstufen erhielt man ungefähr 15% der Nachkommen mit hinreichender Resistenz gegenüber den drei vorgegebenen Eigenschaften. Die Teste wurden in der Lagerzeit der Knollen, die ursprünglich von Sämplingspflanzen stammten, abgeschlossen, so dass sie in der der Aussaat nachfolgenden Saison ausgepflanzt werden konnten. Dans les programmes de sélection de la pomme de terre, de nombreux caractères sont pris en compte et le choix de la succession de leurs mesures a une forte importance sur l'efficacité globale du travail. Quand il y a ségrégation pour des caractères importants et facilement mesurables comme la résistance aux ravageurs et aux maladies, on peut réduire le travail de maintenance du matériel en réalisant des cribles précoces pour ces caractères. Ces tests peuvent être d'abord réalisés à la place des tests de qualité, classiquement effectués en début de programme. Les auteurs décrivent ici une technique de tests de résistance à la fois vis-à-vis des nématodes à kyste et du mildiou. Les résultats de tests de descendance de quatre croisements sont détaillés. La résistance aux nématodes est mesurée par des tests en conteneours dans lesquels le substrat est infesté par un mélange de larves infestantes deGlobodera rostochiensis et deG. pallida. On trouve les résultats globaux en Tableau 2 et les distributions exprimées en valeur relative du nombre de kystes neoformés sont représentées en figures 1A et 1B. Malgré l'absence de répétitions, ces résultats sont en accord avec ceux espérés: le {ie67-1} (Tableau 2) ne montre pas de différence significative pour 3 familles sur 4 avec les résultats théoriques quand c'est la résistance due au gène H1 qui est mesurée. Le cas de non concordance (Tableau 2, famille 4) est explicable par une possible confusion des espèces à la lecture. Cependant, cette source d'erreurs est peu importante quand la sélection est dirigée en même temps contre ces deux espèces. Les clones jugés résistants sont alors testés vis-à-vis dePhytophthora infestans. Ils sont placés en pots et cultivés en serre sous tunnel de polyethylène pour entretenir une forte humidité relative. Une suspension de zoospores d'un isolat complexe est pulvérisée et la sensibilité est appréciée par la surface approximative des lésions nécrotiques du feuillage. Les résultats du Tableau 3 et la distribution relative de la fréquence des clones résistants confirment l'hérédité polygénique de la résistance au mildiou. Environ 15% des familles sont ainsi retenues comme ayant un bon niveau de résistance aux deux espèces deGlobodera et àP. infestans. Les tests, réalisés en hiver, sont achevés à temps pour que les duplicatats, conservés à basse température, identifiés comme résistants puissent être plantés au champ en temps utile, l'année qui suit les semis de graines.

Notizen: Summary The performance of six lines of perennial ryegrass (Lolium perenne L.) which had been selected for three generations for production under spaced plant conditions were assessed under increasing levels of competition, namely spaced plants, drills, miniplots and large sown plots. Successful selection for yield under spaced plant conditions was not accompanied by comparable production patterns in the alternative managements. The extreme situation occurred in swards where a significant decline in production was encountered. Negative or no relationships were found in the establishment year between spaced plant production and yield in the alternative conditions whereas in the first harvest year positive correlations occurred between spaced plants, drills and miniplots and only the latter with plots. These varying patterns of performance are considered in relation to the prediction of sward behaviour and the appropriate environment for selection.

Notizen: Summary Criteria of selection for keeping quality in tulip breeding are reviewed on the basis of a wide range of cultivars and species. The conclusion from an earlier, more limited study that there are large differences in keeping quality between cultivars in several characteristics is confirmed. The choice of the number of days between the onset of flowering and perianth drop as the best criterion is reconsidered because in some cases perianths may remain on the plant long after they have lost their attractiveness. It was found that the sequence in which the various stages (50% discoloration. perianth curving, perianth drop, leaves and stem no longer upright) are reached is not the same for all cultivars and species. None of these phenomena can therefore be used exclusively as criterion of keeping quality. A more comprehensive criterion as the number of days the flower maintains its ornamental value, is useful when commercial cultivars are compared, but for breeding and physiological research attention should be given to all individual aspects of the keeping quality of flower. stem and leaves.

Notizen: Summary Measurements and scores for juvenile plant habit, time to ear emergence, plant height, leaf diseases and 1000 kernel weight were recorded on 123 lines of spring barley grown at Palmerston North, (40°S) New Zealand, and at Cambridge, (52°N) England. The material was grown at both sites from F4 to F7. For juvenile habit, time to ear emergence, plant height and 1000 kernel weight highly significant correlations were found between sites and seasons though few accounted for more than 50 per cent of the variation. There was no evidence of closer correlation between seasons within sites than between sites and seasons, and it was concluded that selection at either site should be equally effective. Analysis of yield performance over sites and seasons within sites revealed large effects due to genotypes and seasons within sites but small effect due to sites. Large interactions were found between genotypes and sites but the genotypes × seasons within sites effect was relatively small; better agreement was found in relative yields between seasons within sites than between sites, so that yield performance in one country was a poor indication of potential performance in the other country. The implications of these results for the use of a selection nursery in New Zealand are discussed.

Notizen: Summary If selection based on F3 yield tests is to be effective, the yield tests must be successful in discriminating among yield genotypes. The available literature indicates that simple tests with limited or no replication are not very effective, although more extensive, replicated tests may be. Data from an experiment comparing F3 yield tests with a single seed descent procedure showed that F3 selection based on a two-replicate test with single seed descent procedure did not justify the extra work involved.

Notizen: Summary More than 7000 MV2 trees derived from 225 MV0 grafts of Cox's Orange Pippin apple that had been treated with approximately 7.5 kR gamma-rays were grown as a solid block with no pollinators in an isolated orchard. The orchard was sited in South Wales well away from any external source of apple pollen and due to this lack of pollination the great majority of the trees produced very few fruit. However, a few individual trees produced acceptable quantities of fruit under these conditions. Twelve trees maintained this performance for seven years and these trees have been selected for trial to test for mutants with increased self-compatibility.

Notizen: Summary Data are presented which support early generation selection for white kernel color in the progeny of red/white kernel wheat crosses which are segregating at 12 or more loci for yield (or any other trait of interest). The optimum generation for selecting white kernels is determined by the frequency of seeds produced with the potential to produce plants having desired quantitative alleles from both parents, and by the frequency of white kernels produced. The F2-produced seed (F3 embryo) is shown to be the optimum generation for selecting white kernels, given that 12 or more loci are segregating for a quantitative character such as yield. When the red parent is a 2 or 3 loci red genotype, selection among F4-produced seed for white kernel color may be desirable when 5 or fewer genes are segregating for the second trait. The results have direct application for all highly heritable, recessive, sporophytic traits.