Germplasm enhancement of maize: a look into haploid induction and chromosomal doubling of haploids from temperate‐adapted tropical sources

The allelic diversity (AD) project of the Germplasm Enhancement of Maize (GEM) programme utilized the double haploid (DH) breeding method to expedite development and release of lines derived from 300 exotic maize races. Using 18 races in this study, differential effects on haploid induction rates (HIRs) and doubling rates (DRs) by the recurrent parents PHB47 and PHZ51, the elevation that the race is traditionally grown at, and by the race itself were addressed in this study. Races from the AD project were grouped by elevation of their origin, high, middle or low altitude. Six races per elevation were randomly selected and backcrossed using both recurrent parents to generate 36 populations. Ten replications were randomized in a complete randomized design for two growing seasons. The recurrent parent effect was significant, with PHB47 having a higher HIR than PHZ51. Effect of elevation was significant with higher HIR associated with low‐elevation origin, and race also proved to be significant. Effects of elevation, recurrent parent and race were not significant for DR.     

Design of a hyperspectral nitrogen sensing system for orange leaves

The orange (Citrus sinensis) is one of the most important agricultural crops in Florida. Heavy reliance on agricultural chemicals and low fertilizer use efficiencies in citrus production have raised environmental and economic concerns. In this study, a nitrogen sensor was developed to predict nitrogen concentrations in orange leaves. Four design criteria were chosen to maximize the sensing efficiency and reliability. They were: (1) coverage of the spectral N sensing range, (2) no moving parts, (3) single leaf detection, and (4) diffuse reflectance measurement. Based on chlorophyll and protein spectral absorption bands, the sensor's wavelength ranges were chosen to be 620–950 nm and 1400–2500 nm. A reflectance housing was designed to block environmental noise and to ensure single leaf measurement. A halogen light source, two detector arrays, two linear variable filters, and data acquisition cards with 16-bit analog-to-digital converters were used to collect data. The designed N sensor had a spectral resolution less than 30 nm. Test results showed that the nitrogen sensor had good linearity (r > 0.99) and stability. With averaged signal-to-noise ratio (SNR) of 299, the system was able to predict N content with a root mean square difference (RMSD) of l.69 g kg⁻¹ for the validation data set. Using the N sensor, unknown leaf samples could be classified into low, medium and high N levels with 70% accuracy.     

Motivations for Enrollment Into the Conservation Reserve Enhancement Program in the James River Basin of South Dakota

The Conservation Reserve Enhancement Program (CREP) targets high-priority conservation needs (e.g., water quality, wildlife habitat) by paying landowners an annual rental rate to remove environmentally sensitive or agriculturally unproductive lands from rowcrop production, and then implement conservation practices on these lands. This study examined motivations of South Dakota landowners for enrolling in the James River Basin CREP. All 517 newly enrolled landowners were mailed a questionnaire in 2014 measuring demographics, behaviors, opinions, and motivations (60% response rate). Cluster analysis of 10 motivations for enrolling identified three motivation groups (wildlife = 40%, financial = 35%, environmental = 25%). The financial group had the youngest mean age (62 years), followed by the wildlife (65) and environmental groups (68). Among respondents, 43% favored the public access requirement of this CREP with the environmental group most in favor. Understanding landowner enrollment motivations and decision criteria will assist in strategies (e.g., financial incentives, increasing yield via habitat restoration) for increasing future participation.     

Wireworm damage reduction in potatoes with an attract-and-kill strategy using <Emphasis Type="Italic">Metarhizium brunneum</Emphasis>

Innovative wireworm control strategies are required to implement integrated pest management on the basis of the (EC) No regulation 1107/2009 and Directive 2009/128/EC. Entomopathogenic fungi, such as Metarhizium brunneum (Metschnikoff) Sorokin, are potential biological control agents for wireworm control but do not achieve high control efficacies in the field when applied as a conidia suspension. In a 2-year study, wireworm control with a novel attract-and-kill strategy aimed at enhancing M. brunneum efficacies in organic potato production systems in Lower Saxony, Germany. The approach is based on the attraction of wireworms (Agriotes spp. Eschscholtz) towards an artificial carbon dioxide-emitting source, using baker’s yeast (Saccharomyces cerevisiae Meyen ex Hansen) in combination with M. brunneum conidia for wireworm infection. Both components were encapsulated in alginate as a carrier material and applied in a mixture with two types of beads (one for encapsulated yeast and one for M.brunneum conidia). An application of these beads within the potato rows during potato planting reduced wireworm tuber damage by 37–75% relative to the untreated control and was able to enhance the efficacy of M. brunneum by up to 35% through an attract-and-kill approach compared to beads without a carbon dioxide source only. This strategy offers a high potential to promote biological wireworm control as an alternative to insecticide use by potentially reducing the inoculum compared to an inundate M. brunneum conidia release strategy.     

Somatic hybrids of vegetable brassicas as source for new resistances to fungal and virus diseases

Somatic hybrids were produced by PEG-induced symmetric and asymmetric protoplast fusions in order to transfer resistance to Alternaria brassicicola, A. brassicae, Phoma lingam, Plasmodiophora brassicae and Turnip mosaic virus (TuMV) into Brassica oleracea var. capitata (cv. ‘Toskama’) and botrytis (cv. ‘Korso’). As resistance donors, ten species belonging to several genera of the family Brassicaceae including wild relatives were used. Of 2,189 plants (somatic hybrids, partially in vitro cloned) tested, 1,616 (73.8%) were resistant against at least one of the pathogens, indicating that, mostly, a successful resistance transfer has taken place. Five hundred and twenty-two hybrids showed multiple resistances to two, three and, in a single case, to four pathogens. Irrespective of the donor parents used in the fusion, a broad variability in symptom manifestation ranging from 0 (without symptoms) to 9 (highly susceptible) could be observed. With regard to the Alternaria pathogens, Sinapis alba, B. nigra and B. juncea were the most effective resistance donors, whereas fusions with Raphanus sativus resulted in the most hybrids with resistance to clubroot and TuMV. As could be shown especially in asymmetric fusions with S. alba, Barbarea vulgaris and Hesperis matronalis, transferred resistance to a pathogen may not correspond with resistance exhibited by the donor parent. Some combinations in which both parents were highly susceptible, e.g. R. sativus (+) B. oleracea var. capitata, yielded hybrids that exhibited strong resistance, e.g. to A. brassicicola, revealing that a new type of resistance might be occurring. With regard to the Alternaria pathogens, resistance expression was very unstable. Many hybrids into which (also variable) resistance of some donors, such as B. vulgaris, S. alba and B. carinata, was transferred became as highly susceptible as those of which the fusion parents did not show any resistance reaction (e.g. R. sativus). For reliable characterization of the resistance response, hybrids should be subjected to several resistance tests during growth period of the host, at least until flowering.     

Pharmacokinetics of buprenorphine in a sodium carboxymethylcellulose gel after buccal transmucosal administration in dogs

Alternatives to intravenous administration of opioids are needed in veterinary medicine. Previous research suggests that opioids can be administered through the buccal mucosa in dogs. This study reports the pharmacokinetics of buprenorphine HCl (0.05 mg/kg) administered transmucosally in six dogs compared with those of buprenorphine HCl (0.015 mg/kg) administered intravenously. The results suggest that the pharmacokinetics of buprenorphine HCl administered intravenously or transmucosally are similar and that transmucosal administration may be considered as a noninvasive alternative to intravenous administration.     

Cumulus Expansion, in vitro Fertilization and Embryonic Development after in vitro Maturation of Bovine Oocytes in the Presence of Follicle Stimulating or Luteinizing Hormone

Contents: Bovine follicular oocytes were matured and fertilize din vitro. The frequency of penetration and subsequent embryonic development were improved considerably, for oocytes cultured in larger volumes allowing larger oocyte groups as compared to the culture of 2 oocytes within 30 μl drops. The effects of follicle stimulating hormone (FSH) and luteinizing hormone (LH), present during in vitro maturation, were studied in terms of cumulus expansion, oocyte penetration, male pronucleus formation and embryonic development. Cumulus expansion including mucification was induced by both hormones. Scanning electron microgfaphs revealed that storage of LH as a frozen solution over a long time period (10 months), destroyed its ability to stimulate cumulus mucification, whereas uncoupling of the cumulus cell processes still occurred. LH caused an increase in the percentage of penetrated oocytes with incomplete sperm head decondensation. This effect was also lost after long term storage. Teh resulting total penetration frequency as well as the proportion of oocytes with both pronuclei formed was now similar to that observed with oocytes matured with fresh LH or FSH. Embryonic development was not altered by the replacement of FSH by LH during in vitro maturation .     

Histological damage by the microbial metabolite and chitin synthesis inhibitor complex nikkomycin to the silk and salivary glands of the mite Tetranychus urticae

The action of the chitin synthesis inhibitor complex nikkomycin on the silk and salivary glands of Tetranychus urticae (Acari, Tetranychidae) was examined with the electron microscope. Histological defects after nikkomycin treatment included a swelling of the cisterna of rough endoplasmic reticulum (ER). Subsequent defects were vacuolation, resulting from globular ER vesicles, and damage to the secretory grana of all the glands studied (the silk gland and the anterior and dorsal podocephalic glands). The consequences of the histological changes on the salivary secretions and the production of webs are discussed.