Routine On-farm Soil Tillage Helps Control Asparagus Fly (Plioreocepta Poeciloptera)

Asparagus fly (Plioreocepta poeciloptera (Schrank, 1776)) is a serious pest in German asparagus (Asparagus officinalis L.) production. To evaluate the effects of different routine on-farm soil tillage measures on the number of flies emerging the following spring, asparagus fields in Lower Saxony, Germany, were investigated. Soil samples were taken before and after tillage in autumn 2017 and autumn 2018. Investigations were also conducted in both years on the effect that the soil depth at which asparagus fly pupae were buried had on the emergence of adult flies.

This study revealed that the number of emerging flies was not reduced by mulching, but was significantly reduced by subsequent tillage and/or tillage and dam formation. The emergence rate of adult flies was significantly reduced the deeper the pupae had been buried the previous autumn. The effects also depended on the year. The highest mean emergence rate observed was 68% and 45% for pupae buried at a depth of 10?cm and 20?cm, respectively. In conclusion, the key mechanism causing a decrease in asparagus fly population the following spring through routine on-farm tillage could be the burial of pupae when forming dams. Routine on-farm soil tillage can be regarded as a physical measure for controlling asparagus fly and is therefore an essential tool in the integrated pest management of asparagus production.

     

Mapping quantitative trait loci conferring blast resistance in upland indica rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

A genetic analysis of blast resistance in upland rice variety is very crucial. In this study, we performed a linkage mapping of quantitative trait loci (QTLs) for blast resistance using an advanced backcross population from a cross between Way Rarem (susceptible indica variety) and Oryzica Llanos 5 (durable resistant indica variety). A transgressive segregation was observed in the advanced backcross population of Way Rarem//Oryzica Llanos 5. A total of 16 QTLs have been identified along chromosomes 1, 3, 5, 6, 7, 8, 9, and 11 against eight blast pathogen isolates. Each QTL accounted from 11.31 to 45.11% of the variation in blast resistance. Most QTLs showed race specificity, demonstrating the small effect of such QTLs. Unexpectedly, several superior blast resistance alleles were contributed by Way Rarem, the susceptible-recurrent parent. Among eight candidate defense response genes detected in several loci, a single gene (oxalate oxidase) present on chromosome 3 was found to be associated with blast resistance in upland indica rice. Ultimately, these advanced backcross lines with resistance to blast tagged by markers might be useful for pyramiding blast resistance alleles in upland rice.     

Hairpin RNAs and retrotransposon LTRs effect RNAi and chromatin-based gene silencing

The expression of short hairpin RNAs in several organisms silences gene expression by targeted mRNA degradation. This RNA interference (RNAi) pathway can also affect the genome, as DNA methylation arises at loci homologous to the target RNA in plants. We demonstrate in fission yeast that expression of a synthetic hairpin RNA is sufficient to silence the homologous locus in trans and causes the assembly of a patch of silent Swi6 chromatin with cohesin. This requires components of the RNAi machinery and Clr4 histone methyltransferase for small interfering RNA generation. A similar process represses several meiotic genes through nearby retrotransposon long terminal repeats (LTRs). These analyses directly implicate interspersed LTRs in regulating gene expression during cellular differentiation.     

Seasonal Biomass Accumulation and Nutrient Uptake of Canola,Mustard, and Flax on a Black Chernozem Soil in Saskatchewan

ABSTRACT

Seed yield and nutrient use efficiency are related to biomass accumulation and nutrient uptake in the growing season. Biomass accumulation and nutrient uptake of canola (Brassica napus L. and Brassica rapa L.), mustard (Brassica juncea L.) and flax (Linum usitatissimum L.) and the relationship to days after emergence (DAE) or growing degree days (GDD) were determined during the 1998 and 1999 growing seasons in field experiments at Melfort, Saskatchewan, Canada. In general, biomass accumulation and nutrient uptake increased with time at early growth stages and reached a maximum at late growth stages. Significant R² values for both biomass accumulation and nutrient uptake indicated that a cubic polynomial type equation was suitable to represent these parameters as a function of DAE. All oilseed crops maximized biomass at mid way to the end of pod forming stages (74–84 DAE or 750–973 GDD). Maximum biomass accumulation rate occurred at the early to late bud forming stage (42–49 DAE or 390–498 GDD), and it was 146–190 kg ha^?1d^?1 for canola, 158–182 kg ha^?1d^?1 for mustard, and 174–189 kg ha^?1d^?1 for flax. Maximum nutrient uptake occurred during flowering to early ripening (59–82 DAE or 597–945 GDD). Maximum nutrient uptake rate normally occurred at branching to early bud formation (21–42 DAE or 142–399 GDD). There was a close correlation between biomass accumulation and nutrient uptake, and among nutrients, suggesting interrelated absorption. For nitrogen (N), phosphorus (P), potassium (K), sulfur (S), and boron (B), respectively, maximum nutrient uptake rate was 2.3–4.5, 0.3–0.5, 2.5–5.7, 0.7–1.1, and 0.005–0.008 kg ha^?1d^?1 for canola; 2.3–3.9, 0.4–0.5, 2.6–4.9, 1.2–1.4, and 0.006–0.008 kg ha^?1d^?1 for mustard; and 3.2–4.0, 0.3–0.4, 2.9–4.1, 0.3–0.5, and 0.004–0.009 kg ha^?1d^?1 for flax. In general, maximum nutrient uptake rate and amount occurred earlier than maximum biomass accumulation rate and amount, and maximum rates of both nutrient uptake and biomass accumulation occurred earlier than their maximum amounts. The findings suggest that for high seed yields, there should be adequate supply of nutrients for plants, particularly to sustain high nutrient uptake rate at branching to bud forming stage and high biomass accumulation rate at early to late bud forming stage.     

The effects of soybean, linseed and marine oils on aerobic gut microbiota of Arctic charr Salvelinus alpinus L. before and after challenge with Aeromonas salmonicida ssp. salmonicida

Populations of heterotrophic bacteria present in the hindgut region of Arctic charr Salvelinus alpinus L. fed dietary soybean, linseed and marine oils before challenge with Aeromonas salmonicida ssp. salmonicida and marine oil after challenge were estimated using the dilution plate technique. There were differences in bacterial composition between the rearing groups before and after challenge, as well as interindividual variations. For example, carnobacteria were only isolated from the hindgut region of fish fed soybean oil and linseed oil before challenge, whereas Carnobacterium spp. and Carnobacterium funditum‐like species were isolated from fish fed the same oils after challenge. Three non‐motile Aeromonas spp. were isolated from infected fish fed marine oil. One of these isolates was identified as identical to A. salmonicida ssp. salmonicida used in&the challenge test by microbial fingerprinting (amplified fragment length polymorphism). Electron microscopic examinations of hindgut regions demonstrated substantial numbers of bacterial cells associated with enterocytes, but bacterial colonization of the enterocyte surface varied between different rearing groups. The potential of bacteria found associated with the hindgut region to inhibit the fish pathogens A. salmonicida, Vibrio salmonicida and Vibrio anguillarum differed between rearing groups.     

Measurement of channel catfish (Ictalurus punctatus) plasma insulin in species-specific radioimmunoassay

A single antibody, equilibrium, species specific radioimmunoassay (RIA) for catfish insulin was developed and validated for measurements of plasma levels of insulin in juvenile and adult channel catfish. The RIA appeared to be sensitive (20 pg/tube) and stable with intra-assay coefficient of variation between 5.7% and 3.1% and inter-assay coefficient of variation of 6.5%. The blood was collected from two strains of catfish, USDA 103 and Norris, which differ in food consumption and growth rates, the former strain consuming more food and growing faster (Silverstein et al. 1999). The experiments conducted from December to May included fasting and feeding periods from 5 to 14 days as well as either intravenous or intraperitoneal administration of glucagon-like peptide known for its anorexic effect in both mammals and fish (Silverstein et al. 2001). As in other piscine species studied before, fed fish had higher plasma insulin content than food-deprived fish. Feeding status prevailed over other treatments as the primary physiological factor determining circulating plasma insulin levels. This revised version was published online in August 2006 with corrections to the Cover Date.     

Chemical Composition and Nutritional Value of Unripe Banana Flour (<Emphasis Type="Italic">Musa acuminata</Emphasis>, var. Nanicão)

Banana flour obtained from unripe banana (Musa acuminata, var. Nanicão) under specific drying conditions was evaluated regarding its chemical composition and nutritional value. Results are expressed in dry weight (dw). The unripe banana flour (UBF) presented a high amount of total dietary fiber (DF) (56.24 g/100 g), which consisted of resistant starch (RS) (48.99 g/100 g), fructans (0.05 g/100 g) and DF without RS or fructans (7.2 g/100 g). The contents of available starch (AS) (27.78 g/100 g) and soluble sugars (1.81 g/100 g) were low. The main phytosterols found were campesterol (4.1 mg/100 g), stigmasterol (2.5 mg/100 g) and β-sitosterol (6.2 mg/100 g). The total polyphenol content was 50.65 mg GAE/100 g. Antioxidant activity, by the FRAP and ORAC methods, was moderated, being 358.67 and 261.00 μmol of Trolox equivalent/100 g, respectively. The content of Zn, Ca and Fe and mineral dialyzability were low. The procedure used to obtain UBF resulted in the recovery of undamaged starch granules and in a low-energy product (597 kJ/100 g).     

Extraction of cellulose nanowhiskers from natural fibers and agricultural byproducts

In this work the feasibility of extracting cellulose from cotton, sisal and flax fibers, corn stover and rice husk by means of usual chemical procedures such as acid hydrolysis, chlorination, alkaline extraction, and bleaching was analyzed. Cellulose nanowhiskers from these sources, and from commercial cellulose, were produced by the acid hydrolysis of the obtained celluloses. The final products were characterized by means of Thermogravimetric Analysis (TGA), Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electronic Microscopy (SEM) and Atomic Force Microscopy (AFM). The chemical procedure used to obtain cellulose nanowhiskers was effective in all cases but differences on the thermal stability, chemical composition, crystallinity and morphology were found due to the dissimilar nature of the different sources. Thus, this work demonstrates that the morphology and physical properties of cellulose nanowhiskers synthesized by the same conditions are strongly dependent on their source.