[Corn straw composting in the field and in situ fertilizer effect].

According to the fact that corn straws remain or burned in the field in hilly and mountainous areas of Southwest China, which causes organic matter waste and serious atmospheric pollution, it is necessary to develop an efficient method to compost the corn straws. In the present experiment, corn straws were placed on the landside and land corner for composting with thermophilic cellulous bacteria inoculated, chemical nitrogen and nitrogen absorption agent added, and then covered with polyethylene film (bio-composting). Thereafter, flue-cured tobacco grown in the same land was fertilized with the compost to study the fertilizer effect. The results showed that the temperature in bio-compost increased quickly (over than 35 degrees C within 2 to 3 days) but decreased slowly compared to natural composting (control). In the bio-compost, temperature over than 50 degrees C lasted for about 15 days and the number of bacteria was 100 to 1000 times higher than in the control de- spite that microbial groups decreased in the high temperature period. After 90 days of bio-composting, corn straws contained water less than 25% with pH 6. 14 and showed brown or black color and fragmental or farinose physical state, indicating good decomposition and humification. Meanwhile, the active organic matter and nutrients, including N, P and K, were significantly increased. The yield, mean price, economical output of flue-cured tobacco leaves were increased and the leaf quality was improved by application of chemical fertilizers plus the compost at the ratio of 1:1. Therefore, bio-composting could utilize efficiently corn straws and eliminate air pollution, which is worth popularization in hilly and mountain areas.

Genome Sequencing of Ralstonia solanacearum FQY_4, Isolated from a Bacterial Wilt Nursery Used for Breeding Crop Resistance.

Ralstonia solanacearum strain FQY_4 was isolated from a bacterial wilt nursery, which is used for breeding crops for Ralstonia resistance in China. Here, we report the complete genome sequence of FQY_4 and its comparison with other published R. solanacearum genomes, especially with the strains GMI1000 and Y45 in the same group.

A rapid microbioassay for discovery of antagonistic bacteria for Phytophthora parasitica var. nicotianae.

A simple, rapid, small-scale microbioassay for infection of tobacco seedlings by Phytophthora parasitica var. nicotianae was developed here. This assay uses tobacco seedlings cultivated in petri dishes for a standardized method for quantitation of initial zoospore inocula and high-throughput screening of antagonistic bacteria. Zoospore inocula between 10(2) to 10(5) spores per petri dish were inoculated on 14-day-old tobacco seedlings for the susceptibility test. The optimum inocula was established to be ten thousand zoospores. One hundred and fifty pure culture bacteria with different pigments, growth rates, and morphologies were isolated from rhizosphere soil of tobacco and screened for protective ability against tobacco black shank. Fifteen bacteria presented high activity against P. parasitica on tobacco seedlings. They were identified by Biolog GEN III MicroPlate and distributed as Bacillus amyloliquefaciens, B. licheniformis, Paenibacillus pabuli, B. atrophaeus, B. subtilis, B. pumilus, and B. endophyticus, respectively. Four antagonists chosen randomly from the 15 bacteria all exhibited the same 100% protective activity in planta as that in the petri dishes. This microassay proved to be a rapid, reproducible, and efficient method for screening of potential biological agents or microorganisms and may be useful for studying mechanisms of infection and control of Phytophthora spp. under hydroponic conditions.