Genetic variation for nitrate content between cultivars of endive (Cichorium endiviae L.)

Summary A high nitrate content is a negative quality trait in vegetables. Endive (Cichorium endiviae L.) contributes considerably to human nitrate intake in Northwestern Europe. A collection of 125 commercially available cultivars of endive were grown on nutrient solution and evaluated for genetic variation between cultivars for the nitrate concentration in expressed sap. In two subsequent experiments 23 cultivars, representing the range of nitrate levels found in the first experiment, were grown both in soil and on nutrient solution. There were significant differences between cultivars in nitrate accumulation. Cultivar Vicor consistently had the lowest nitrate content. Averaged over all experiments the nitrate concentration in expressed sap of this cultivar was 0.7 g·l^-1 (19%) lower than that of two recommended cultivars. The results indicate that there may be some possibilities to reduce the nitrate content of endive by cultivar choice or breeding. However, the chances of obtaining a substantial reduction of the nitrate content of endive seem less than in some other crops, such as lettuce. The nitrate levels of the cultivars showed interactions with experiments and growth medium. There was no correlation between the cultivar means for the concentrations of nitrate and chloride, or between the concentration of nitrate and the osmolarity of the plant sap.     

Inheritance of partial resistance to Myzus persicae in lettuce

Summary The genetics of partial resistance of lettuce to Myzus persicae was studied using F₁ and F₂ generations of two crosses between a susceptible and partially resistant accession (Norden x Batacer and Liba x Norden) and three crosses in which both parents were partially resistant (Batavia la Brillante x Batacer, Batacer x Liba and CGN4741 x Batacer). Partial resistance to M. persicae inherited quantitatively, without important dominance effects. Only in the cross Batacer x Liba were significant departures of the F₁ and F₂ from the midparent found, which were probably caused by epistatic effects. Reciprocal F₁s had similar resistance levels, indicating the absence of cytoplasmic or other maternal effects. Estimates of broad-sense heritability ranged from 0.34 to 0.61. The results indicated that lines with an improved resistance level can be obtained from crosses between partially resistant accessions, preferably by line selection or the application of indirect marker aided selection.Abbreviations PR partial resistance, partially resistant - S susceptibility, susceptible     

P40 polyester sheet plastination technique for brain and body slices: The vertical and horizontal flat chamber methods

The P40 technique produces high‐quality brain and body slices and is the user‐friendliest of the polyester techniques. The P40 polyester technique follows the same classical steps for plastination. That is, preparation of the specimen, fixation (optional), dehydration by freeze substitution, forced impregnation and curing. Two methods used to prepare two different types of specimens, that is, brain slices and body slices are described. Each method has its own characteristics depending on the specimen type used. Brain slices were used to illustrate the vertical small chamber method while the body slices were used to illustrate the horizontal large chamber method. The brain slices obtained using P40 are of very good quality presenting good contrast between grey and white matter. The body slices are also of very good quality. The physical appearance of these slices makes them an exceptional instrument for diagnostic imaging and anatomical correlation. Body slices prepared with P40 retain the natural colour of the tissue and preserve the anatomical relationships.     

Rice yields and yield gaps in Southeast Asia: Past trends and future outlook

Rice production must increase to meet future food requirements amid strong competition for limited resources. Yield gap analysis is a useful method to examine how large the ranges are between potential, desirable rice yields and those actually realized in farmers’ fields. We analyzed farmers’ yields in wet and dry seasons in four intensively cropped rice areas in Southeast Asia and explored opportunities for reducing the yield gap to meet future food requirements. We found yield gaps of 2.0-5.0 t ha⁻¹ between average and climatic yield potential and 1.2-2.6 t ha⁻¹ between average and best farmers’ yields. In relative terms, average yields varied between 43% and 75% of the climatic yield potential and 61% and 83% of the best farmers’ yields. Farmers with best yields were generally more educated, and used fertilizers and labor more efficiently than average farmers. The yield gaps between average and best farmers’ yields are higher in rice-importing countries (Indonesia and Philippines) compared with rice-exporting countries (Thailand and Vietnam). Assuming no change in diet, closing the existing yield gap between average and best-yielding farmers can sufficiently cover the yield increase needed for 2050 in the three countries, except for the Philippines, where yield increase must be even higher. Trend analysis of yield increases of a population of farmers in Central Luzon (Philippines), which included a learning curve analysis, well described the process of technology adoption from 1966 to 2008, leading to higher yields. Using this analysis, for the Philippines, we predicted yields to increase (from 2007/2008 to 2050) by only 18% with current cultivars, production technologies, and prevailing conditions. Therefore, structural changes are needed to boost farmers’ yields to close the yield gap faster. Investments in technology transfer and institutional arrangements are suggested.     

Experimental verification and development of EPIPRE,a supervised disease and pest management system for wheat

From 1981 to 1984, 27 experiments were carried out to evaluate and develop the EPIPRE system for supervised pest and disease management in wheat. The results of these experiments led to an adjustment of the EPIPRE recommendation for control ofSeptoria spp. After this adjustment only minor differences remained between EPIPRE and the general recommendation in the number and type of sprays and in net yields. The EPIPRE advice models for stripe rust, leaf rust, mildew and cereal aphids were reliable. More research is needed onSeptoria spp. and the modelling of pesticide action and efficiency. Reduction in pesticide application as a result of using EPIPRE was less than was expected at the start of the EPIPRE project. A reason for this is that pesticide use in wheat in the Netherlands is low in comparison with surrounding countries. Application of sprays above the level of EPIPRE recommendation were often found to be economically worthwhile, but their economic advantage, compared to the adapted EPIPRE recommendation or to the general recommendation, was small and did not justify intensive, high-input crop protection strategies. EPIPRE had positive educational effects, but probably few short-term economic benefits for the farmer. This limits the participation in the advice system. In the future the EPIPRE information on disease and pest management will be incorporated into a computerized management system for wheat growing, that comprises all crop husbandry measures from sowing to harvest.Samenvatting Van 1981 tot 1984 werden 27 proeven uitgevoerd om het EPIPRE-systeem voor geleide bestrijding van ziekten en plagen in tarwe te evalueren en verder te ontwikkelen. De resultaten van deze experimenten gaven aanleiding tot een forse aanpassing van het EPIPRE-advies voorSeptoria spp. Na deze aanpassing verschilden het EPIPRE advies en het Algemene advies, zoals gegeven door de Voorlichtingsdientst, nog slechts weinig wat betreft het aantal en het type van de bespuitingen en de netto opbrengst. De EPIPRE-adviesmodellen voor gele roest, bruine roest, meeldauw en bladluizen bleken te voldoen. VoorSeptoria spp. en het modelleren van de werking en efficiëntie van bestrijdingsmiddelen is meer onderzoek nodig. De reductie in het gebruik van bestrijdingsmiddelen door gebruik van EPIPRE bleek minder te zijn dan aanvankelijk werd verwacht. Een van de redenen hiervoor is dat het gebruik van bestrijdingsmiddelen in de tarweteelt in Nederland laag is in vergelijking met omringende landen. Vaker spuiten dan EPIPRE adviseerde bleek vaak economisch verantwoord, maar het voordeel t.o.v. EPIPRE of het Algemene advies was klein en geeft geen reden om over te gaan tot intensieve bestrijdingsregimes. Deelnemers aan EPIPRE waarderen de educatieve aspecten van het systeem, maar hebben waarschijnlijk op korte termijn slechts weinig economische voordelen van deelname. Dit bemoeilijkt de uitbreiding van het aantal deelnemers. In de komende jaren zal de EPIPRE-advisering ingebouwd worden in een compleet geautomatiseerd teeltbegeleidingssysteem, dat alle belangrijke teelthandeling van zaaien tot oogsten zal bevatten.     

Distribution and activity of spray deposits in an oak canopy following aerial application of diluted and undiluted formulations of Bacillus thuringiensis Berliner against the gypsy moth,Lymantria dispar L. (Lepidoptera: Lymantriidae)

The distribution and biological activity of spray deposits resulting from aerial applications of diluted and undiluted Bacillus thuringiensis, ‘Dipel 64AF’ against the gypsy moth, Lymantria dispar L., were examined in oak stands in south-eastern Ontario, Canada. The sprays were applied by fixed-wing aircraft equipped with four ‘Micronair AU4000’ atomizers. Application of diluted formulation at 30 BIU ha^?1 in 6.0–6.4 litre generally resulted in a higher droplet density (10–28 cm ^?2 leaf) than application of undiluted product at the same dosage rate in 1.8 litre ha^?1 (4–10 cm ^?2). However, spray deposits of undiluted product with a volume median diameter (D_v.5) of 90–130 μm caused as much mortality of gypsy moth larvae in bioassays of sprayed foliage as deposits of diluted product with a D_v.5 of 150–350 μm despite a two- to three-fold reduction in droplet density. Our data suggest that by using fine spray atomization, undiluted application of these formulations can offer the same efficacy against gypsy moth as coarsely atomized sprays of diluted product.     

Radiographic and clinical changes of the tibial tuberosity after tibial plateau leveling osteotomy

OBJECTIVE: To investigate radiographic changes of the tibial tuberosity after tibial plateau leveling osteotomy (TPLO) surgery and identify clinical findings and risk factors associated with such changes. STUDY DESIGN: Retrospective study. SAMPLE POPULATION: Hundred and eighty-six client-owned dogs (219 stifles) that had TPLO surgery. METHODS: Patient data retrieved included radiographic changes of the tibial tuberosity during re-examination, age, body weight, whether unilateral or single-session bilateral surgery had been performed, location of the anti-rotational pin, approximate tibial tuberosity area, and approximate average tibial tuberosity width. RESULTS: Fracture with resulting caudal displacement of the proximal tibial tuberosity (1.4%; 3 of 219) occurred less frequently than non-displaced tibial tuberosity fractures (7.3%; 16 of 219). Age, weight, average tibial tuberosity width, location of the anti-rotational pin, and single session bilateral surgery were identified as risks factors for non-displaced fracture. Weight divided by the square of the average tibial tuberosity width may be a stronger risk factor than either weight or average tibial tuberosity width alone. CONCLUSIONS: Dogs undergoing single session bilateral TPLO surgery are at greater risk for developing non-displaced tibial tuberosity fractures. The non-displaced tibial tuberosity fracture does not appear to adversely affect outcome or lead to tibial tuberosity avulsion. Significant risk factors for fracture of the proximal tibial tuberosity with caudal displacement were not identified. CLINICAL RELEVANCE: Factors including age, weight, tibial tuberosity thickness, and conditions that may enhance strain on the tibial tuberosity, such as single-session bilateral procedures, may increase risk of fracture.