Bleeding canker, a devastating disease of pear trees (Pyrus pyrifolia L.), was first reported in the 1970s in Jiangsu, China and more recently in other provinces in China.  Trees infected with bleeding canker pathogen, Dickeya fangzhongdai, develop cankers on the trunks and branches, and a rust-colored mixture of bacterial ooze and tree sap could be seen all over the trunks and branches.  In this study, we provided detail descriptions of the symptoms and epidemiology of bleeding canker disease.  Based on pathogenic and phenotypic characterizations, we identified the causal agent of bleeding canker of pear as D. fangzhongdai.  Dickeya fangzhongdai strains isolated from pear were also pathogenic on Solanum tuberosum, Brassica pekinensis, Lycopersicon esculentum, and Phalaenopsis aphrodite based on artificial inoculation, and the pathogen were more virulent on potato than that of D. solani strain.  This study provides new information about this disease and bleeding canker disease of pear.

The aim of this study was to evaluate the growth of rape (Brassica napus L.) seedlings under different light intensities to select appropriate conditions for cultivation in an indoor system.  Seedlings were grown under different light intensities of red and blue light provided by light-emitting diodes (LEDs) and their self-adjustment ability and changes in leaf microstructure were evaluated.  Light was supplied by red LEDs with peak wavelengths of 630 (R₁) and 660 nm (R₂) and by blue LEDs (B) with a peak wavelength of 445 nm (the light intensity ratio of R₁:R₂:B was 3:3:2), at intensities of 400 (R₁R₂B400), 300 (R₁R₂B300), and 200 μmol m^–2 s^–1 (R₁R₂B200).  Natural solar light served as the control (C).  Plant height, stem diameter, root length, leaf area, and dry weight of rape seedlings gradually increased with increasing light intensity.  The seedlings in the R₁R₂B400 treatment grew more vigorously, while those in the R₁R₂B200 treatment were weaker.  The photosynthetic pigment contents did not differ significantly between the R₁R₂B400 treatment and C, but were significantly lower in the R₁R₂B300 and R₁R₂B200 treatments.  The highest intercellular CO₂ concentration, stomatal conductance, and transpiration rate were in the R₁R₂B300 treatment.  The highest photosynthetic rate was in the R₁R₂B400 treatment, and was related to more compact leaves, thicker and tidier palisade and spongy tissues, and well-developed chloroplasts.  In contrast, the seedlings in the R₁R₂B200 treatment had disordered mesophyll cells, round chloroplasts, and fractured and fuzzy grana lamellae, all of which inhibited plant growth.  In conclusion, the seedlings in the R₁R₂B400 treatment had well-developed leaves, which favored photosynthesis.  Compared with the light intensities below 300 μmol m^–2 s^–1, the light intensity of 400 μmol m^–2 s^–1 provided by a combination of red and blue LEDs was beneficial for cultivating strong and healthy rape seedlings in an artificial system.  

Using a household survey data collected from four leading maize producing provinces in China, this paper studies the decisions of maize farmers on seed choices and variety portfolios when asymmetrical information exists in the market. Our findings indicate, while farmers generally tend to adopt new varieties with the expectation of potential higher yield, the primary driver to do so for those who have less information on seed varieties is to reduce production risk. Improving seed market management and providing more seed information to farmers would be beneficial in choosing seed varieties and maize production.