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Experiments were conducted to identify environmental factors that influence the survival of rainbow smelt Osmerus mordax during their early life stages. Developing rainbow smelt embryos and yolk-sac larvae were cultured under controlled conditions with different dissolved oxygen (DO; 1·09, 2·18, 4·37 and 6·55 mg l−1, pH (4·0, 4·5, 5·0, 5·5, 6·0 and 7·0), nitrate (0·7, 3·6, 7·3, 14·6 and 29·2 mg l−1), phosphate (0·04, 0·21, 0·42, 2·08 and 4·17 mg l−1) and salinity (0, 5, 10, 15, 20 and 30) levels. Rainbow smelt embryos were also incubated with simulated tidal salinity fluctuations (2–28), ultraviolet radiation (irradiances of 2·8, 6·2 and 5·1 W m−2) and under natural conditions in two rainbow smelt spawning rivers. In the laboratory, hatch was only impaired under the lowest DO and pH conditions (0 and 13% hatch, respectively) and at highest constant salinity levels (0% hatch). Larval survival was only affected by pH levels ≤5·0. The experiment that compared hatch under natural conditions was terminated when embryos became covered with silt and fungus. These results suggest that water acidification, sediment and fungal growth may affect rainbow smelt survival during their early life stages.

Cavity spot is a major disease of carrots, causing cavities on the surface of the root. Available commercial varieties show a range of susceptibility but no significant resistance. Seed progeny from 46 tissue culture-derived carrot (Daucus carota) somaclones were screened for viability, then 19 selected somaclone families were sown under glasshouse conditions, along with commercial cultivars (Bertan, Nandor, Bolero and Vita Longa) as controls. Mature roots were exposed to Pythium violae in a cavity spot bioassay to determine their response as measured by disease incidence and severity. Some somaclones formed fewer lesions than the least susceptible control cultivar, Vita Longa. Seven somaclonal families that showed a range of susceptibility were sown under field conditions and the assessment was repeated. Although there was little relationship between glasshouse and field-trial results, under field conditions one of the somaclones had a mean incidence of disease, as estimated by transformed data, of 1·9 compared with 37·9 for the most susceptible somaclone and 3·5 for Bolero, the most resistant commercial cultivar. The results indicated that significant genetic variation in susceptibility to cavity spot disease was present in the somaclones.

Edaphic factors affect the quality of onions (Allium cepa). Two experiments were carried out in the field and glasshouse to investigate the effects of N (field: 0, 120 kg ha(-1); glasshouse: 0, 108 kg ha(-1)), S (field: 0, 20 kg ha(-1); glasshouse: 0, 4.35 kg ha(-1)) and soil type (clay, sandy loam) on onion quality. A conducting polymer sensor electronic nose (E-nose) was used to classify onion headspace volatiles. Relative changes in the E-nose sensor resistance ratio (%dR/R) were reduced following N and S fertilisation. A 2D Principal Component Analysis (PCA) of the E-nose data sets accounted for c. 100% of the variations in onion headspace volatiles in both experiments. For the field experiment, E-nose data set clusters for headspace volatiles for no N-added onions overlapped (D-2 = 1.0) irrespective of S treatment. Headspace volatiles of N-fertilised onions for the glasshouse sandy loam also overlapped (D-2 = 1.1) irrespective of S treatment as compared with distinct separations among clusters for the clay soil. N fertilisation significantly (P < 0.01) reduced onion bulb pyruvic acid concentration (flavour) in both experiments. S fertilisation increased pyruvic acid concentration significantly (P < 0.01) in the glasshouse experiment, especially for the clay soil, but had no effect on pyruvic acid concentration in the field. N and S fertilisation significantly (P < 0.01) increased lachrymatory potency (pungency), but reduced total soluble solids (TSS) content in the field experiment. In the glasshouse experiment, N and S had no effect on TSS. TSS content was increased on the clay by 1.2-fold as compared with the sandy loam. Onion tissue N:water-soluble SO42- ratios of between five and eight were associated with greater %dR/R and pyruvic acid concentration values. N did not affect inner bulb tissue microbial load. In contrast, S fertilisation reduced inner bulb tissue microbial load by 80% in the field experiment and between 27% (sandy loam) and 92% (clay) in the glasshouse experiment. Overall, onion bulb quality discriminated by the E-nose responded to N, S and soil type treatments, and reflected their interactions. However, the conventional analytical and sensory measures of onion quality did not correlate with %dR/R.

Flavour in fresh onions is dominated by volatile sulphenic and thiosulphenic acids that are liberated once alk(en)yl cysteine sulphoxide (ACSO) flavour precursors are cleaved by the enzyme alliinase after tissue disruption. The levels of pyruvate and ACSOs in over 100 samples of onions marketed in the UK were measured, and compared with assessment by taste-panels. There was a linear relationship between the content of ACSOs and pyruvate. Measurements of pyruvate indicated that the marketing classification of some types of onion did not correspond to their pyruvate levels. A significant linear relationship was found between a sensory measure of strength and pyruvate over the range 1.2–9.3 µmol pyruvate g−1 fresh weight. In most cases, when a flavour classification of sweet, mild or strong was applied to a sample of onions based on pyruvate content, the taste-panels agreed with the categorization. The taste-panels were unable to identify a sweet flavour in onions, except at low levels of pyruvate. Taste-panels were able to define a likeability character (attractiveness of flavour) for onions, which correlated with the level of pyruvate. However, for some varieties, the flavour classification or likeability did not correspond to predictions based on pyruvate levels alone. Pyruvate measurements were seen as a suitable method for routine quality control once the characteristics of a variety of onion had been established, but initial evaluations should include well-designed taste-panel assessments. Copyright © 2004 Society of Chemical Industry

The extent to which resistance to leek rust (Puccinia allii) in commercially useful cultivars of leek (Allium ampeloprasum) could be developed by selection within current commercial cultivars or their recent predecessors was investigated. Differences in resistance among commercial cultivars was not great. However, a wide range of resistance levels was found in both half-sib and inbred progeny derived from these cultivars. In a crop simulation, one of the breeding lines showed a reduction in the rate of new pustule appearance of 44% compared to cv. Wintra. It is concluded that selection within modern cultivar level material is a potentially productive strategy for the commercial development of leek rust resistance in the short to medium term.

A biological metal extinction (bacterial leaching) process has been developed to extract metals from sludge. Although the removal of metals from sludge is a significant step, an, biological hazard must be eliminated before the sludge can be used on land. Earlier studies established that indicator bacteria were not reduced significantly during bacterial leaching. Whether pathogens also would survive or be destroyed in the acidic environment of the bacterial leaching process was not determined. This study was intended to answer this question. A series of batch units performing bacterial leaching was operated with varying sludge concentrations spiked with attenuated Salmonella typhimurium. The concentrations of Salmonella typhimurium and total coliforms in the sludge were determined

Summary Results are presented for the performance of improved inbred lines of Brussels sprouts grown in replicated and fully guarded plots. Some lines were identified which out-performed the reference F1 hybrid, Gower, for the yield of marketable sprouts and for sprout quality. No lines were found which were superior for both of these traits. These results support earlier contentions that inbred line performance in Brussels sprouts could be improved to levels comparable with those of commercial F1 hybrids. The genetic gains required to achieve commercial parity with hybrids for all agronomically important traits continue to be large. Therefore, the use of inbred lines as commercial cultivars can only be viewed as a long term objective. Previous studies have identified additive x additive epistasis and the segregation of many loci as important factors limiting the genetic gains to be expected from a single cycle of crossing and inbreeding. In addition to these factors the current study identifies areas of difficulty encountered when attempting to screen and select large numbers of inbred lines, produced either by single seed descent or by anther culture, in a single season. Evidence is presented which suggests that imperfect visual selection and/or genotype × seasonal interactions may substantially reduce the efficiency of selections based upon a single trial of very many unreplicated lines.

SUMMARY Previous work at the National Vegetable Research Station indicated that cross-pollination of Brussels sprouts by honeybees could be improved when parent lines with similar flowering characteristics were used. During 1973-5 inbred lines were tested at three sites for matching ability based on flowering times, plant height and flower colour. One pair of inbreds satisfied all criteria at all sites, and a further twelve gave satisfactory results. Two pairs visually matched in 1973 were grown in larger plots in 1973-4 to assess the effect of matching on honeybee behaviour. Results showed that matching improved cross-pollination by honeybees between the parent lines.

SUMMARY The feasibility of producing commercially acceptable inbred lines of Brussels sprouts is investigated. Two experiments are described which examined the nature and extent of heterosis in this crop using the techniques of biometrical genetics. They indicate incomplete dominance for several production traits, lower F1 uniformity and the presence of inbreds that outyield some F1's. These results strongly suggest that recombinant inbred lines, possibly outyielding the better F1's could be produced. Five crosses were identified for inbreeding by SSD and 1000 lines are being produced from each. The principles upon which these crosses were identified are described.

Summary 100 babies (98 with haemolytic disease of the newborn) have been observed during exchange transfusion. Serial estimations of plasma potassium, sodium, chloride, protein, total calcium, citrate, and certain organic acids have been made in selected cases. We have found a positive correlation but not an absolute one between a high plasma citrate concentration and illness or death during exchange transfusion. It is possible that citrate directly or indirectly is the cause of these crises. We have outlined a plan for conducting exchange transfusion using bank blood collected in ACD which in our hands has proved satisfactory in the past three years. Resume 100 enfants, dont 98 atteints de maladie hemolytique du nouveaune, ont ete observes pendant l'exsanguino transfusion. Des dosages du potassium, du sodium, des chlorures, des protelnes, du calcium total, du citrate et de certains acides organiques ont ete pratiques dans certains cas selectionnes. Nous avons trouve un rapport qui n'est toutefois pas absolu entre une concentration trop forte de citrate plasmatique et des exsanguinotransfusion mal supportees, voire fatales. II est possible que le citrate en soit la cause, directement ou indirectement. Nous avons esquisse notre maniere de pratiquer l'exsanguinotransfusion permettant d'utiliser des sangs ACD qui, durant ces trois dernieres annees, s'est demontre, quant a nous, satisfaisant. Zusammenfassung 100 Neugeborene, wovon 98 einen Morbus haemolyticus neonatorum aufwiesen, wurden wahrend der Austauschtransfusion genauer beobachtet. Bei einzelnen ausgewahlten Fallen wurden Reihenbestimmungen des Plasma-Kaliums, -Natriums, der Chloride und Proteine, des Gesamt-Calciums, des Zitrates sowie gewisser organi-scher Sauren durchgefuhrt. Wir beobachteten eine positive, wenn auch nicht absolute Korrelation zwischen hohen Plasma-Zitrat-Konzentrationen und Schadigungen bzw. Tod des Kindes wahrend der Austauschtransfusion. Es ist moglich, das das Zitrat die direkte oder indirekte Ursache dieser Zwischenfalle darstellt. Wir beschrieben eine Methode zur Durchfuhrung von Austauschtransfusionen unter Verwendung von ACD-Blutkonserven, welche uns wahrend der vergangenen drei Jahre gute Dienste geleistet hat.