Acid Rain Increases Impact of Rice Blast on Crop Health via Inhibition of Resistance Enzymes.

Worldwide, rice blast (Pyricularia oryzae) causes more rice crop loss than other diseases. Acid rain has reduced crop yields globally for nearly a century. However, the effects of acid rain on rice-Pyricularia oryzae systems are still far from fully understood. In this study, we conducted a lab cultivation experiment of P. oryzae under a series of acidity conditions as well as a glasshouse cultivation experiment of rice that was inoculated with P. oryzae either before (P. + SAR) or after (SAR + P.) simulated acid rain (SAR) at pH 5.0, 4.0, 3.0 and 2.0. Our results showed that the growth and pathogenicity of P. oryzae was significantly inhibited with decreasing pH treatments in vitro culture. The SAR + P. treatment with a pH of 4.0 was associated with the highest inhibition of P. oryzae expansion. However, regardless of the inoculation time, higher-acidity rain treatments showed a decreased inhibition of P. oryzae via disease-resistance related enzymes and metabolites in rice leaves, thus increasing disease index. The combined effects of high acidity and fungal inoculation were more serious than that of either alone. This study provides novel insights into the effects of acid rain on the plant-pathogen interaction and may also serve as a guide for evaluating disease control and crop health in the context of acid rain.

Effects of simulated acid rain on microbial characteristics in a lateritic red soil.

A laboratory experiment was performed to examine the impact of simulated acid rain (SAR) on nutrient leaching, microbial biomass, and microbial activities in a lateritic red soil in South China. The soil column leaching experiment was conducted over a 60-day period with the following six SAR pH treatments (levels): 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0 and one control treatment (pH = 7). Compared with the control treatment, the concentrations of soil organic matter, total nitrogen, total phosphorus, total potassium, soil microbial biomass carbon (MBC), soil microbial biomass nitrogen (MBN), and average well color density (AWCD) in the Ecoplates were all significantly decreased by leaching with SAR at different pH levels. The decrease in MBC and MBN indicated that acid rain reduced the soil microbial population, while the decrease in AWCD revealed that acid rain had a negative effect on soil bacterial metabolic function. Soil basal respiration increased gradually from pH 4.0 to 7.0 but decreased dramatically from pH 2.5 to 3.0. The decrease in soil nutrient was the major reason for the change of soil microbial functions. A principal component analysis showed that the major carbon sources used by the bacteria were carbohydrates and carboxylic acids.

[Gender differences of Pomacea canaliculata in cold tolerance].

In order to understand whether Pomacea canaliculata exhibits gender differences in cold resistance, the survival rate and supercooling point of both P. canaliculata females and males were investigated at low temperature. The changes in physiological and biochemical indices in the body of P. canaliculata before and after the winter were also examined. The results showed that the mean supercooling point of females was -6.83 degrees C, which was significantly lower than that of the males (-6.26 degrees C). With the arrival of winter, the amounts of bound water, glycerol, lipid and glycogen of P. canaliculata increased, while the amount of free water decreased. These indices except glycerol showed significant differences between males and females. More than 90% non-acclimated snails could survive at the temperature of 10 degrees C for 7 days. The survival rate of snails exhibited significant differences in sex and shell height after being transferred at 5 degrees C for 7 days. In addition, more females were recorded during field investigation. Based on these results, we concluded that the females had higher cold tolerance than the males. This finding would provide some references for further investigation of ecological adaptation, natural sex ratio and cold tolerance mechanisms of P. canaliculata.

Physiological responses of mangrove Sonneratia apetala Buch-Ham plant to wastewater nutrients and heavy metals.

Mangroves play an important role for removing nutrients, heavy metals, and other pollutants in wetland ecosystems. This study investigated the physiological responses of a mangrove plant (i.e., Sonneratia apetala Buch-Ham) to different wastewater pollution levels. Four different treatments, namely three concentration levels (i.e., normal, five-time-greater than normal, and ten-time-greater than normal) of wastewaters and one control (i.e., salted water), were used to grow the mangrove plants. Results showed that the height and biomass of the plant increased with wastewater pollution levels. No significant differences in root and catalase activities were observed among different treatments, whereas the increases in peroxidase and superoxide dismutase activities were attributed to the need for detoxification. In general, leaf chlorophyll content increased with wastewater pollution levels due to the increase in nutrient contents.

[Directions of ecology specialty construction and personnel training in China].

This paper analyzed the present status of ecology specialty construction and personnel training in China. It was considered that there existed some problems to be solved, e. g., the contradiction between the rapid development of new subjects in ecology and the relative weakness in personnel qualified to teach, the unbalance between the extensive and intensive, and the deep and shallow teaching programs for the students in ecology, the conflict between the "soft" (theoretical) ecological education and the "hard" (technical) ecological construction, and the contradiction between the limited demands and the relative surplus supply of undergraduate students in ecology. Based on these analyses, a series of suggestions and countermeasures for the innovation of the teaching styles and training directions in ecological specialties were put forward, including 1) to formulate a development and construction plan of ecology specialty and to appropriately regulate the enrollment of undergraduate students, 2) to achieve the changes in current teaching styles from classroom to field and from "soft" theoretical teaching to "hard" technical training, 3) to develop and implement a variety of diversified teaching methods, such as participative, interactive, research-based, and innovative teaching for undergraduate students, 4) to enhance the undergraduate educational quality and teaching resource bank construction and to achieve teaching resource sharing, and 5) to establish "T-type" personnel training system in ecology. Some employment-oriented personnel training directions in ecology specialty were also presented.