Effect of pea bacterial blight (Pseudomonas syringae pv. pisi) on the yield of spring sown combining peas (Pisum sativum)

Field trials to examine the effect of pea bacterial blight (Pseudomonas syringae pv. pisi) (Psp) on the yield of combining peas were carried out at five sites (HRI Wellesbourne, ADAS Rosemaund, ADAS Terrington, PGRO, SASA East Craigs) in the UK in 1990, 1991 and 1992. Healthy seed, cv. Solara, and seed naturally infected with Psp Race 2 was sown in large plots (c. 200 m²) in the open or under nets to prevent bird damage by pigeons. Despite relatively low disease severity levels (< 15% leaf area) and separation by at least 12 m of cv. Consort (resistant to Race 2) between plots there was considerable spread of disease into plots sown with healthy seed. Regression analysis demonstrated a significant relationship between yield and disease. Of the disease measurements examined, disease severity on the leaves (stipules) at growth stage 208 was found to be the best predictor of yield. A model containing environmental and bird damage terms, in addition to disease, suggested that a yield loss of 0.98 t/ha would be expected for a disease severity score of 1, equivalent to 5% leaf area affected, at growth stage 208.     

Further studies relating chlorogenic acid concentration in carrots to carrot fly damage

The effects of first generation carrot fly larval damage on chlorogenic acid concentration in carrots was investigated in a field experiment at Wellesbourne in 1985. In a separate experiment carrots grown in the absence of a resident population of carrot fly were also analysed for chlorogenic acid; these carrots maintained low concentrations of chlorogenic acid through the summer and autumn until low ground temperatures occurred from November to January. The relationship between chlorogenic acid concentration and damage by the first generation of carrot fly was described by a similar model to the one derived previously for late-generation damage but without the cultivar dependence. This may have been because first generation damage takes place in mid-summer when soil temperature is not sufficiently low for differential chlorogenic acid production by carrot cultivars. The model supports the hypothesis that carrot fly damage increases chlorogenic acid production which subsequently encourages further attack. The increase in acid production due to the low winter temperature may be the mechanism which, in turn, induced a differential cultivar response in carrots harvested during the winter.     

USE OF TACTILE AND VISUAL CUES IN CONSUMER JUDGMENTS OF APPLE RIPENESS

The relative importance of visual and tactile cues in consumer assessments of'Royal Gala'apple ripeness were studied in relation to commercial maturity indices which included background color, blush, weight and skin greasiness. Apples were evaluated by consumers under 3 sensory conditions to isolate their use of visual and tactile cues. Individual fruit were harvested to provide apples which independently varied in background color, blush and weight. Visual cues of skin color were found to be greater drivers of perceived apple ripeness than tactile cues of skin greasiness and apple firmness. Amongst the visual cues tested, the hue of the background color had the greatest impact on consumer judgments of'Royal Gala'apple ripeness. Consumer's ideal'Royal Gala'apple ripeness was achieved with a background color between chip levels 5 and 8, blush coverage between 33-66% and weighing between 130-142 g.     

A RAPID ASSESSMENT APPROACH FOR EVALUATING SILVER CARP GENDER

Silver carp Hypophthalmichthys molitrix were introduced into the U.S. to control water quality in aquaculture ponds. From this point of origin, silver carp escaped into nearby rivers through multiple flood events. Because of their documented negative effects on native biota, silver carp have been labeled as problematic. Therefore, evaluating the biology and ecology of these non-indigenous species is critical. Multiple parameters are needed to evaluate silver carp populations(length, weight, age, and sex). Furthermore, developing methods for rapidly acquiring these data are needed. In relation to sex determination, sexual dimorphism was observed where males exhibit distinct pectoral fin ray features. Specifically, males have pronounced ridges or a "rough patch" on the dorsal surface of pectoral fins. Therefore, to test if this was an applicable way of determining silver carp gender; silver carp were collected from Midwestern U.S. rivers(N=2015) in the fall of 2011(N=870), spring of 2012(N=645), winter of 2013—2014(N=202) and summer2015(N=323) via electrofishing. For each silver carp collected, presence(e.g., rough patch) or absence(e.g.,smooth) of pronounced ridges on the top side of the pectoral fins was recorded, and an incision was made in the body cavity to identify gender. Based on the results of our evaluation, gender was correctly identified over99% of the time(2006 out of 2015) based on the pectoral fin dimorphism. In the samples taken in the winter of 2013—2014 and summer of 2015, accuracy for silver carp shorter than 300 mm and longer than 800 mm was 53.7%(19 out of 41) while accuracy for silver carp between 300 mm and 800 mm total length was 98.9%(289 out of 292). This study provides a rapid assessment approach for evaluating silver carp gender.     

The effects of time of sowing and harvest on carrot biochemistry and the resistance of carrots to carrot fly

Two carrot cultivars which represented contrasting levels of resistance to carrot fly, Psila rosae, were grown in a replicated field experiment at Wellesbourne in 1984–85. Seed was sown on five occasions between April and August 1984 and the crop harvested after a minimum growth in the field of 16 wk on seven occasions between August 1984 and February 1985. A highly significant correlation (r = -0.78; P > 0.001) between the levels of carrot fly damage and the concentration of chlorogenic acid in the roots enabled a model to be formulated to predict the relative predisposition to carrot fly larval damage; high levels of chlorogenic acid early in the season predisposed roots to severe attack when they were older.     

Onion (Allium cepa L.) Seedling Emergence Patterns can be Explained by the Influence of Soil Temperature and Water Potential on Seed Germination

A theory is outlined that seedling emergence patterns in thefield are largely generated by the influence of soil water potentialon a critical event (i.e. the initiation of radicle growth)that determines the base water potential for germination. Abovethis base the mean rate and distribution of seedling emergenceare largely determined by temperature. This proposal was expressedas a parsimonious stochastic model to test whether patternsof seedling emergence recorded in field experiments could beexplained. The model applies current understanding of the influence ofwater potential and thermal time on germination under controlledconditions to the variable environment of horticultural seedbeds. Where possible, parameter values were taken from the literature,others were inferred from laboratory experiments on seed germinationand seedling emergence. The model accurately predicts the onsetof seedling emergence and the occurrence and timing of subsequentseedling flushes in a wide range of seed bed conditions. The study indicates that a co-ordinated use of existing seed-bedpreparation techniques to retain soil moisture for initial seedimbibition and limited irrigation, timed to coincide with thecritical period when radicle growth is initiated in the seedpopulation, may provide an approach to improving crop uniformitythat is simple and practical. Key words: Onion, germination, seedling emergence, thermal time, water potential     

Immunohistochemical expression of rabphilin-3A-like (Noc2) in normal and tumor tissues of human endocrine pancreas

Involvement of rabphilin-3A-like (RPH3AL), or Noc2, the potential effector of Ras-associated binding proteins Rab3A and Rab27A in the regulation of exocytotic processes in the endocrine pancreas has been demonstrated in experimental models. Noc2 expression together with other regulatory molecules of the exocytotic machinery in human tissues, however, has not been studied. We evaluated immunohistochemical expression of the key molecules of the exocytotic machinery, Noc2, Rab3A, Rab27A, and RIM2, together with the characteristic islet cell hormones, insulin and glucagon in normal and endocrine tumor tissues of human pancreas. Normal pancreatic islets were stained for all of these proteins and showed strong cytoplasmic localization. A similar pattern of strong cytoplasmic expression of these proteins was observed in the majority of endocrine tumors. By contrast, the exocrine portions of normal appearing pancreas completely lacked Rab27A staining and showed decreased expression of the proteins, Noc2, Rab3A, and RIM2. The staining pattern of Noc2 and Rab27A was similar to the staining pattern of glucagon-producing cells within the islets. The concomitant expression of Noc2 with these molecules suggests that Noc2 may serve as an effector for Rab3A and Rab27A and that it is involved in the regulation of exocytosis of the endocrine pancreas in humans.