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. 相似文献
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... 相似文献
? 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 CO2Larix 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.
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,... 相似文献
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.
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. 相似文献
Our research evaluates and compares the effects of three land‐related policies on land development in a sprawling metropolitan area during a real estate boom and a recession. Our findings suggest that during a real estate boom 1) the urban growth boundary (UGB) serves its purpose of attracting urban development inside the given boundary during a boom while its effectiveness diminishes with increased development pressure from lower‐valued land outside of the UGB during a recession period, 2) the agricultural zone works well for restraining new development during a boom period while agriculture zoned parcels are more likely developed during a recession period, and 3) an increase in the land‐value tax bill increases the incentive for development during a recession period while higher tax bills do not affect development during a boom period. In anticipation of a re‐emergence of urban sprawl with the recovery of the real estate market, our findings imply that land planners and others concerned with sprawling development should pay more attention to development in sprawl‐prone areas during recession periods. 相似文献
Summary In this study, the application of molecular markers to optimise genetic diversity in a polycross breeding program of perennial
ryegrass (Lolium perenne L.) was evaluated. The genetic diversity among 98 potential parental plants from three maturity groups (early, intermediate
and late flowering) was investigated using amplified fragment length polymorphism (AFLP) markers. For each maturity group,
two polycrosses of six parental plants with contrasting levels of genetic diversity were composed. Average genetic diversity
among parents selected for narrow polycrosses was 36% lower than among parents selected for wide polycrosses. Diversity within
first generation synthetic progenies (Syn1) was proportional to the diversity within the respective parental polycrosses.
However, differences were less pronounced with Syn1 progenies from narrow polycrosses showing 16% reduced diversity when compared
to Syn1 progenies from wide polycrosses. Multivariate analyses allowed for a clear separation of the six Syn1 progenies based
on AFLP markers and demonstrated their genetic distinctness. Evaluation of dry matter yield, date of ear emergence and stem
length of Syn1 and Syn2 progenies showed progenies from wide polycrosses to be constantly higher yielding when compared to
progenies from narrow polycrosses. On the other hand, there was no significant difference in variability for the two morphological
traits between progenies of narrow- and wide polycrosses. The results presented here provide evidence for an efficient application
of molecular markers to select genetically diverse polycross parents which resulted in an average yield increase of 3.8%. 相似文献