K De Witte

Use of the multi-allelic self-incompatibility gene in apple to assess homozygocity in shoots obtained through haploid induction

Abstract To obtain homozygous genotypes of apple, we have induced haploid development of either the female or the male gametes by parthenogenesis in situ and anther culture, respectively. Of the shoots obtained, which were mainly of a non-haploid nature, some could be derived from fertilised egg cells or from sporophytic anther tissue. In order to select the shoots having a true haploid origin, and thus homozygotes, we decided to use the single multi-allelic self-incompatibility gene as a molecular marker to discriminate homozygous from heterozygous individuals. The rationale behind this approach was that diploid apple cultivars contain 2 different alleles of the S-gene and therefore the haploid induced shoots obtained from them should have only one of the alleles of the single parent. The parental cultivars used were ‘Idared’ (parthenogenesis in situ) and ‘Braeburn’ (androgenesis), and their S-genotypes were known, except for 1 of the ‘Braeburn’S-alleles. To stimulate parthenogenetic development ‘Idared’ styles were pollinated with irradiated ‘Baskatong’ pollen, the S-alleles of the latter (2n) cultivar were also unknown. The cloning and sequence analysis of these 3 unidentified S-alleles, 1 from ‘Braeburn’ and 2 from ‘Baskatong’ is described, and we show that they correspond to the S24-, S26- and S27-alleles. We have optimised a method for analysis of the S-alleles of ‘Idared/Baskatong’- or ‘Braeburn’-derived in vitro plant tissues and have shown that this approach can be applied for the screening of the in vitro shoots for their haploid origin.

Mean and Bold? On Separating Merger Economies from Structural Efficiency Gains in the Drinking Water Sector

The Dutch drinking water sector experienced two drastic changes over the last 10 years. Firstly, the sector association started a voluntary benchmarking aimed to increase the efficiency and effectiveness of the sector. Secondly, merger activity arose. This paper develops a nonparametric model to dissect and distinguish the effects on efficiency of these evolutions. Parametric corrected ordinarily least squares (Fourier) tests show the robustness of the model with respect to the specification and its variables. Although detecting an efficiency enhancing effect of benchmarking, we find insignificant merger economies due to the absence of scale economies and the absence of increased incentives to fight inefficiencies.

Assessing pupil and school performance by non-parametric and parametric techniques

AbstractThis paper discusses the use of the non-parametric free disposal hull (FDH) and the parametric multi-level model (MLM) as alternative methods for measuring pupil and school attainment where hierarchical structured data are available. Using robust FDH estimates, we show how to decompose the overall inefficiency of a unit (a pupil) into a unit specific and a higher level (a school) component. By a sample of entry and exit attainments of 3017 girls in British ordinary single sex schools, we test the robustness of the non-parametric and parametric estimates. Finally, the paper uses the traditional MLM model in a best practice framework so that pupil and school efficiencies can be computed.

Designing Incentives in Local Public Utilities: An International Comparison of the Drinking Water Sector

Cross-country comparisons avoid the unsteady equilibrium in which regulators have to balance between economies of scale and a sufficient number of remaining comparable utilities. By the use of Data Envelopment Analysis (DEA), we compare the efficiency of the drinking water sector in the Netherlands, England and Wales, Australia, Portugal and Belgium. After introducing a procedure to measure the homogeneity of an industry, robust order-m partial frontiers are used to detect outlying observations. By applying bootstrapping algorithms, bias-corrected first and second stage results are estimated. Our results suggest that incentive regulation in the sense of regulatory and benchmark incentive schemes have a significant positive effect on efficiency. By suitably adapting the conditional efficiency measures to the bias corrected estimates, we incorporate environmental variables directly into the efficiency estimates. We firstly equalize the social, physical and institutional environment, and secondly, deduce the effect of incentive schemes on utilities as they would work under similar conditions. The analysis demonstrates that in absence of clear and structural incentives the average efficiency of the utilities falls in comparison with utilities which are encouraged by incentives.

Equity and Efficiency in Private and Public Education: A Nonparametric Comparison

We present a nonparametric approach for the equity and efficiency evaluation of (private and public) primary schools in Flanders. First, we use a nonparametric (Data Envelopment Analysis) model that is specially tailored to assess educational efficiency at the pupil level. The model accounts for the fact that minimal prior structure typically available for the behavior (objectives and feasibility set) under evaluation, it reckons with outlier behavior in the available data, while it corrects for ‘environmental’ characteristics that are specific to each pupil. Second, we propose first- and second-order stochastic dominance (FSD and SSD) criteria as naturally complementary aggregation criteria for comparing the performance of different school types (private and public schools) in Flanders. While FSD only accounts for (Pareto) efficiency, SSD also takes (Pigou-Dalton) equality into consideration. We find that private schools outperform public schools in terms of SSD.

Restrictions of the efficiency of haploid plant production in apple cultivar Idared, through parthenogenesis in situ

For haploid plant production in Idared apple, parthenogenesis in situ was induced by irradiated pollen. The most important restrictions were seed set, embryo germination and green plant recovery from germinated embryos. The efficiency of green plant production was strongly influenced by irradiation dose, picking time and quality of the irradiated pollen. 250 Gy pollen was more efficient for green plant production than 500 Gy pollen. Using 250 Gy pollen with reduced germination capacity resulted in a five-fold lower green plant yield. Delaying picking of the fruits (140 instead of 70 days after pollination) had a significant positive effect. Up to 20 plants per 1000 pollinated flowers, showing no expression of a marker gene present in the pollen parent, were obtained in some treatments.

Accounting for Economies of Scope in Performance Evaluations of University Professors

Teaching and research are widely regarded as the two key activities of academics. We propose a tailored version of the popular Data Envelopment Analysis methodology to evaluate the overall performance of university faculty. The methodology enables accounting for the potential presence of economies of scope between the teaching and research activities. It is illustrated with a dataset of professors working at a Business and Administration department of a university college. The estimation results reveal that overall the performance scores of faculty decrease if we allow for spillovers from research to teaching and vice-versa.

Plant regeneration from cotyledons and embryonic axes in apple: Sites of reaction and effect of pre-culture in the light

Mature embryos of the cultivar Gloster were isolated from seeds of fruits stored at 1 °C. Embryonic axes and wounded cotyledons were pre-cultured in the light for 0 to 6 days on embryo growth medium (experiment 1) or for 0 to 24 hours on shoot induction medium (experiment 2). After a subsequent dark period of 3 weeks for induction of organogenesis, explants were cultured in the light on shoot elongation medium. Up to 95% of the embryos formed shoots, while the mean shoot number per embryo reached 6.4. Regeneration frequency was influenced by the type of explant: embryonic axes reacted better (75%) than the tops of the cotyledons (29%) or wounds on the cotyledons (9%). The mean total shoot number per embryo comprised means of 2.3 for embryonic axes, 1.8 for tops of cotyledons and 2.3 for wounds on cotyledons (experiment 1). Wounds on the proximal part of the cotyledon reacted much better than those on other parts. Shoot differentiation was highest when cotyledons were cultured with the adaxial side on the medium, suggesting that there exist gradations within the cotyledon for regeneration capacity (experiment 2). The number of shoots per reactive site was not normally distributed, while a high frequency of 6 or more shoots per reactive site was found (experiment 1). A pre-culture of more than 24 hours in the light seemed to have negative effect, but there was no clear evidence whether this was a light and/or a medium effect.