Intensive organic vegetable production increases soil organic carbon but with a lower carbon conversion efficiency than integrated management

Intensive vegetable production in greenhouses has rapidly expanded in China since the 1990s and increased to 1.3 million ha of farmland by 2016, which is the highest in the world. We conducted an 11‐year greenhouse vegetable production experiment from 2002 to 2013 to observe soil organic carbon (SOC) dynamics under three management systems, i.e., conventional (CON), integrated (ING), and intensive organic (ORG) farming. Soil samples (0–20 and 20–40 cm depth) were collected in 2002 and 2013 and separated into four particle‐size fractions, i.e., coarse sand (> 250 µm), fine sand (250–53 µm), silt (53–2 µm), and clay (< 2 µm). The SOC contents and δ¹³C values of the whole soil and the four particle‐size fractions were analyzed. After 11 years of vegetable farming, ORG and ING significantly increased SOC stocks (0–20 cm) by 4008 ± 36.6 and 2880 ± 365 kg C ha^?1 y^?1, respectively, 8.1‐ and 5.8‐times that of CON (494 ± 42.6 kg C ha^?1 y^?1). The SOC stock increase in ORG at 20–40 cm depth was 245 ± 66.4 kg C ha^?1 y^?1, significantly higher than in ING (66 ± 13.4 kg C ha^?1 y^?1) and CON (109 ± 44.8 kg C ha^?1 y^?1). Analyses of ¹³C revealed a significant increase in newly produced SOC in both soil layers in ORG. However, the carbon conversion efficiency (CE: increased organic carbon in soil divided by organic carbon input) was lower in ORG (14.4%–21.7%) than in ING (18.2%–27.4%). Among the four particle‐sizes in the 0–20 cm layer, the silt fraction exhibited the largest proportion of increase in SOC content (57.8% and 55.4% of the SOC increase in ORG and ING, respectively). A similar trend was detected in the 20–40 cm soil layer. Over all, intensive organic (ORG) vegetable production increases soil organic carbon but with a lower carbon conversion efficiency than integrated (ING) management.     

Role of integrons in the proliferation of multiple drug resistance in selected bacteria occurring in poultry production

ABSTRACT

• 1. The increase in microbial resistance, and in particular multiple drug resistance (MDR), is an increasing threat to public health. The uncontrolled use of antibiotics and antibacterial chemotherapeutics in the poultry industry, especially in concentrations too low to cause inhibition, and the occurrence of residues in feed and in the environment play a significant role in the development of resistance among zoonotic food-borne microorganisms.

• 2. Determining the presence and transmission methods of resistance in bacteria is crucial for tracking and preventing antibiotic resistance. Horizontal transfer of genetic elements responsible for drug resistance is considered to be the main mechanism for the spread of antibiotic resistance.

• 3. Of the many well-known genetic elements responsible for horizontal gene transfer, integrons are among the most important factors contributing to multiple drug resistance. The mechanism of bacterial drug resistance acquisition through integrons is one of the essential elements of MDR prevention in animal production.

     

Are microconidia infectious principles in Neonectria ditissima?

Journal of Plant Diseases and Protection - Comparative studies of different isolates of Neonectria ditissima obtained from canker lesions and rotten fruit showed that both five-septate macroconidia...     

Effects of atmospheric and climate change at the timberline of the Central European Alps

? This review considers potential effects of atmospheric change and climate warming within the timberline ecotone of the Central European Alps. After focusing on the impacts of ozone (O₃) and rising atmospheric CO₂ concentration, effects of climate warming on the carbon and water balance of timberline trees and forests will be outlined towards conclusions about changes in tree growth and treeline dynamics.

? Presently, ambient ground-level O₃ concentrations do not exert crucial stress on adult conifers at the timberline of the Central European Alps. In response to elevated atmospheric CO₂ Larix decidua showed growth increase, whereas no such response was found in Pinus uncinata. Overall climate warming appears as the factor responsible for the observed growth stimulation of timberline trees.

? Increased seedling re-establishment in the Central European Alps however, resulted from invasion into potential habitats rather than upward migration due to climate change, although seedlings will only reach tree size upon successful coupling with the atmosphere and thus loosing the beneficial microclimate of low stature vegetation.

? In conclusion, future climate extremes are more likely than the gradual temperature increase to control treeline dynamics in the Central European Alps.

     

Stem injection of prohexadione carboxylic acid to protect blossoms of apple trees from fire blight infection (Erwinia amylovora)

Journal of Plant Diseases and Protection - Stem injection of prohexadione carboxylic acid (pca) was tested to prevent blossom infection by the fire blight pathogen Erwinia amylovora on apple trees,...     

A rapid and simple method for determining fungicide resistance in Botrytis

A simple test based on the germination of conidia of Botrytis on agar media augmented with various fungicides has been developed. Average concentrations causing a 50% reduction of germ-tube growth (EC₅₀) of highly sensitive isolates were determined on 1% malt extract agar (thiophanate-methyl 0.090 ppm; iprodione 0.566 ppm; fludioxonil 0.026 ppm; fenhexamid 0.144 ppm), 1% malt extract agar with 100 ppm salicyl hydroxamic acid (QoI fungicides, viz. trifloxystrobin 0.009 ppm; pyraclostrobin 0.013 ppm; azoxystrobin 0.087 ppm), 0.5% yeast extract agar (boscalid 0.069 ppm) and 0.5% sucrose agar (cyprodinil 0.053 ppm). In order to detect different levels of resistance against these various fungicides, two discriminatory concentrations were identified for each compound. A routine assay method was developed in which drops of a conidial suspension harvested directly from diseased plant material or sporulating cultures were incubated on each of 20 different agar media. Because of a very short time-span of 24–48 h between sample collection and evaluation of results, field-specific information on the occurrence, frequency and types of resistance of Botrytis against common botryticides in soft-fruit production may be generated prior to the main fungicide spray season at blossom time.

     

Differing trophic niches of three French stygobionts and their implications for conservation of endemic stygofauna

1. Groundwater ecosystems represent the greatest proportion of unfrozen freshwater on Earth and harbour high numbers of rare taxa with restricted distributions. Stygofaunal abundance, species richness, and ecology play essential roles in groundwater ecosystem services and functioning, as well as providing an important contribution to global biodiversity. However, as global depletion and contamination of groundwater pose serious and often irreversible threats to stygofauna, more information is urgently needed about the ecology of rare groundwater species to guide effective strategies for their conservation or restoration.
2. In this study, analyses of carbon and nitrogen stable isotopes were used to compare and evaluate trophic niches and diets of a vulnerable stygobiont isopod, Gallasellus heilyi living in sympatry in French groundwater ecosystems with the isopod Caecosphaeroma burgundum and the amphipod Niphargus ladmiraulti.
3. Stable isotope results showed trophic niche partitioning among the three stygobiont species and indicated that G. heilyi and C. burgundum occupy the role of primary consumers and N. ladmiraulti that of predator. Moreover, although G. heilyi and C. burgundum were shown to rely on the same food sources, indicating similar diets, and their trophic niches did not overlap, suggesting trophic specialization.
4. The results suggest that detritus (i.e. decaying organic material) is an important food source for G. heilyi, and its availability could determine the survival of this endangered species. As a practical conservation measure for G. heilyi and the whole stygofauna community, we suggest reconnecting surface and subterranean ecosystems, as they probably were before natural sinks and many wells were filled up or closed.

     

Agronomic performance of late-season rice under different tillage,straw, and nitrogen management

In double rice-cropping system in China, zero tillage in late-season rice with straw return from early season rice is an emerging technology for saving inputs, shortening the lag time between rice crops, avoiding straw burning, and conserving natural resources. The objective of this 2-year field study was to determine the effects of tillage and straw return on N uptake, grain yield, and N use efficiency of late-season rice. Treatments were arranged in a split-plot design with four combinations of tillage and straw return as main plots and three N management practices as subplots. Tillage was either conventional soil puddling or zero tillage with newly harvested crop residue from early season rice either removed or placed on the soil surface without incorporation. The N treatments were zero-N control, site-specific N management (SSNM), and farmers’ N-fertilizer practice (FFP). Straw return regardless of tillage or N management did not reduce rice yield. In the second year, straw return significantly increased grain yield in the zero-N control. Chlorophyll meter readings at heading and total N uptake at maturity were higher with straw return in the zero-N control, suggesting that straw provides nutrients to rice in the late growing period. Zero tillage did not reduce N uptake, grain yield, and N use efficiency compared with conventional tillage. Despite large differences in timing and rate of N application between FFP and SSNM, these two N treatments resulted in comparable N uptake and grain yield of late-season rice regardless of tillage and straw return. These results suggest that zero tillage after early rice with straw return could replace conventional tillage for late rice in the double rice-cropping system in China.