Influence of bean rhizosphere on the biological properties and phosphorus fractionation in the calcareous soils amended with municipal sewage sludge

The biological and chemical conditions of the rhizosphere are known to considerably differ from those of the bulk soil, as a consequence of a range of processes that are induced either directly by the activity of plant roots or indirectly by the stimulation of microbial population and activity in the rhizosphere. Information about phosphorus （P） fractionation in the rhizosphere soils amended with municipal sewage sludge （MSS） is limited, were We carried out greenhouse experiments using a rhizobox in order to evaluate the effects of bean rhizosphere on the various inorganic P （Pi） fractions, organic P （Po）, P in particulate fraction （PF-P）, Olsen-P, dissolved organic C （DOC）, microbial biomass P （MBP） and alkaline phosphatase （ALP） enzyme in 10 calcareous soils amended with MSS （10 g MSS was added to 1 kg soil）. Non-occluded P, occluded P, calcium phosphate and residual P were also quantitated. The results showed that DOC, MBP and ALP activity strongly increased and PF-P and Olsen-P de- creased in the rhizosphere soils compared with in the bulk soils （P〈0.05）. The contents of non-occluded P, oc- cluded P and residuaI-P fractions in the rhizosphere soils were lower than in the bulk soils, while the contents of calcium phosphate and organic P in the rhizosphere soils were higher than in the bulk soils. Simple correlation coefficients showed that P uptake had positive relationship with non-occluded P, occluded P, calcium phosphate fractions and PF-P in the rhizosphere soils. The results suggest that the short-term application of MSS to the cal- careous soils may increase Po and calcium phosphate fractions in the rhizosphere soils, and calcium phosphate fraction is potentially available to crops.

Response of Leaf Tissue Structure to PP333 in Korla Fragrant Pear

[Objective] This study was performed to explore the effect of different concentrations of PP333 on leaf tissue structure of Korla fragrant pear and to lay the foundation for the cultivation and regulation of Korla fragrant pear. [Method] The leaf tissues treated with different concentrations of PP333 were dehydrated with al- cohol, embedded in paraffin and sliced into 10-μm slices. The thicknesses of leaf blade, upper epidermis, lower epidermis, palisade tissue and sponge tissue were measured, and the ratio of palisade to spongy layer thickness, cell tightness （CT） and cell looseness （CL） were calculated. [Result] The thickness of leaf blade, the ratio of palisade to sponge layer thickness and the thickness of palisade layer were all significantly increased after treatment with PP333. Treatment with 2 500 mg/L PP333 showed no obvious effect on the thickness of leaf epidermis, but increased the thicknesses of leaf blade and palisade tissue. Leaf CL was the highest in the treatment of 1 500 mg/L PP333. [Conclusion] PP333 can increase the leaf thickness, palisade tissue thickness and CT, reduce spongy tissue thickness and CL of Korla fragrant pear. Additionally, 1 500 mg/L was the optimal concentration for the application of PP333 to improve the cold resistance of Koda fragrant pear.

1-MCP Improved Diverse Sensorial, Biochemical and Physical Apple Traits during Cold Storage Based on Cultivar

Apple cultivars’ storability could be strengthened through known techniques of cold storage, advanced industries of control atmosphere or other routine usages like fruit pre-cooling followed by immersion in CA++ solution, depending on genetic potential of the plant material. At the end of pomology and cold storage assessments of 93 apple cultivars, two high yielding native 'Dirras-e Mashhad' and 'Wealthy' were treated by single and combined 1-MCP and ethylene nano-absorbent (ENA) to assess eventual improvements in cold storage span, fruit eating quality and role of cultivar. For this purpose, directs effects and interactions between all sources of variance were studied. Ethylene emission and CO2 amounts were measured. The results showed that reduced weight loss and flesh firmness, were registered in the treated samples of both cultivars compared with the control. Using of 1-MCP affected significantly (p 0.05) on these characteristics. The native apple 'Dirras-e Mashhad' showed higher pH value than 'Wealthy' under the combined treatment (ENA+1-MCP). Genetic source revealed significant difference through lower 'Wealthy' storability. Ethylene emission increased to 53.64 ppm/Kg·hr after 5th month, which resulted in significant difference at p > 0.01 level related to the initial value of 3.26 ppm/Kg·hr. The combined treatment (ENA+1-MCP) affected significantly (p < 0.05) most of the fruit characteristics in both of the cultivars. The treatments demonstrated different results by cultivar.

Stability and Sensory Quality of Dried Papaya

Fruit dehydration is a way of supplying the population with healthy and nutritious foods. The shelf life of dried fruit can be defined by the evaluation of changes occurred in chemical characteristics during storage. This study aims to evaluate the sensory quality and the stability of papaya cv. Tainung n° 1 dehydrated by convective drying. Fresh and dried papaya were evaluated for color, moisture, pH, acidity, water activity, soluble solids, vitamin C, carotenoids, total extractable polyphenols (TEP) and antioxidant activity (ABTS). The sensorial acceptance of the dried papaya was evaluated using a structured nine-point hedonic scale. For the stability study, the analysis of moisture, pH, titratable acidity, water activity, total carotenoids and vitamin C were carried out every 30 days of storage until 120 days. During storage, the moisture content of dried papaya remained constant, but there were undesirable changes in color, increase of acidity and reduction of soluble solids. The degradation of total carotenoids and vitamin C followed the first order reaction, and the half-life time was 346 days for carotenoids, whereas for vitamin C it was only 29 days. In the sensory analysis, the dried papaya received grades between 5.0 and 6.0 for all evaluated attributes. Dried papaya is recommended to be consumed up to 30 days, since within this period a product with higher total carotenoids content, vitamin C and with satisfactory physicochemical and sensorial characteristics were obtained.

Response of Leaf Tissue Structure to Exogenous ABA in Korla Fragrant Pear

To study the effects of different concentrations of Abscisic Acid(ABA) on leaf tissue structure of Korla fragrant pear and lay the foundation for the cultivation and regulation of Korla fragrant pear. Using the paraffin section method, the leaf thickness, the epidermis thickness, the palisade tissue thickness and the sponge tissue thickness were measured; palisade spongy ratio, Cell Tightness(CT) and Cell Looseness(CL) were examined after treatments with exogenous ABA. Leaf thickness, leaf palisade spongy ratio and palisade tissue thickness increased significantly after exogenous ABA treatment compared with CK, while the effect on leaf epidermis was not obvious. The leaf thickness and palisade tissue thickness increased evidently after 70 mg · LABA treatment by 24.89% and 41.10%, respectively. The tissue structures of leaves were more compact, while CL was lower after 70 and 90 mg · LABA treatments. The effects of different concentrations of exogenous ABA could increase the leaf thickness, palisade tissue thickness of Korla fragrant pear and CT, reduced the thickness of spongy tissue and CL. Among those concentrations of exogenous ABA, the effect of spraying 70 mg · Lexogenous ABA was suitable for improving cold resistance of Korla fragrant pear.

Residue Dynamics of 20% Propargite Agent in Apple and Soil

To clear the degradation regularity of propargite in apple, the liquid chromatography was applied to study the residue and degradation dynamics of 20% propargite agent in apple and soil. The results showed that the half life of propargite in apple was 14.6-36.2 d, which was 7.1-8.6 d in soil. When the dosage of 20% propargite agent was 1 500-3 000 ml/hm^2, and the agent was sprayed for 2-3 times, the residues in apple and soil were less than 1.28 mg/kg. With comprehensive consideration on environmental safety, when 20% propargite agent was used to control apple mites, the recommended dosage was 1 500 ml/hm^2, the agent could be sprayed for 2-3 times, and the safety interval was 14 d.

Roles of DEMETER in regulating DNA methylation in vegetative tissues and pathogen resistance

DNA methylation is an epigenetic mark important for genome stability and gene expression.In Arabidopsis thaliana,the 5-methylcytosine DNA glycosylase/demethylase DEMETER(DME)controls active DNA demethylation during the reproductive stage;however,the lethality of loss-of-function dme mutations has made it difficult to assess DME function in vegetative tissues.Here,we edited DME using clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated protein 9 and created three weak dme mutants that produced a few viable seeds.We also performed central cell-specific complementation in a strong dme mutant and combined this line with mutations in the other three Arabidopsis demethylase genes to generate the dme ros1 dml2 dml3(drdd)quadruple mutant.A DNA methylome analysis showed that DME is required for DNA demethylation at hundreds of genomic regions in vegetative tissues.A transcriptome analysis of the drdd mutant revealed that DME and the other three demethylases are important for plant responses to biotic and abiotic stresses in vegetative tissues.Despite the limited role of DME in regulating DNA methylation in vegetative tissues,the dme mutants showed increased susceptibility to bacterial and fungal pathogens.Our study highlights the important functions of DME in vegetative tissues and provides valuable genetic tools for future investigations of DNA demethylation in plants.