Incorporation of fallow weed increases phosphorus availability in a farmer’s organic rice fields on allophanic Andosol in eastern Japan

ABSTRACT

We investigated the amount of soil phosphorus (P) in a farmer’s paddy fields under organic farming (OF) for various periods from 0 to 22 years as well as other farmers’ fields under conventional farming. All the fields are located in allophanic Andosol with long history of P fertilizer application, and some of them have been converted to OF across years. After conversion to OF, P was supplied only with winter fallow weeds mainly Foxtail (Alopecurus aequalis), rice residues (rice bran and straw), and guano. We determined total-P (Tot-P) and plant-available P (Av-P), which consists of Truog-P (Tru-P) and Bray-2-P under reducing condition with ascorbic acid (Asc-P), in soils of each field. For both Av-Ps, the ratio to Tot-P increased across years under OF following quadratic functions with both linear and quadratic terms being statistically significant. The ratios showed little changes for the initial 15 (Tru-P) or 10 (Asc-P) years and increased rapidly thereafter. These temporal changes in Av-P were consistent with the rapid increase of the amount of P accumulated in the winter fallow weeds and incorporated in the fields after beginning of OF. These results led us to the hypothesis that the incorporation of winter weeds has contributed to the increase of Av-P in the organic fields across years. We tested this hypothesis by investigating temporal changes of Av-P after suspending the weed incorporation for 2 consecutive years in plots of the organic fields. Both Av-Ps were significantly greater in plots with continued weed incorporation (CWI) than those in plots with its suspension. We further found that the increase of Asc-P in plots with CWI was 4.9-fold the input of total P in the incorporated weeds. This suggests that the incorporation of winter fallow weeds enhanced soil-P availability beyond the supply of P accumulated in the weeds.     

Improvement and validation of the method to determine neutral detergent fiber in feed

To improve the performance of the analytical method for neutral detergent fiber in feed with heat‐stable α‐amylase treatment (aNDFom), the process of adding heat‐stable α‐amylase, as well as other analytical conditions, were examined. In this new process, the starch in the samples was removed by adding amylase to neutral detergent (ND) solution twice, just after the start of heating and immediately after refluxing. We also examined the effects of the use of sodium sulfite, and drying and ashing conditions for aNDFom analysis by this modified amylase addition method. A collaborative study to validate this new method was carried out with 15 laboratories. These laboratories analyzed two samples, alfalfa pellet and dairy mixed feed, with blind duplicates. Ten laboratories used a conventional apparatus and five used a Fibertec^® type apparatus. There were no significant differences in aNDFom values between these two refluxing apparatuses. The aNDFom values in alfalfa pellet and dairy mixed feed were 388 g/kg and 145 g/kg, the coefficients of variation for the repeatability and reproducibility (CV_r and CV_R) were 1.3% and 2.9%, and the HorRat values were 0.8 and 1.1, respectively. This new method was validated with 5.8% uncertainty (k = 2) from the collaborative study.     

Analysis of gene sequences for the nucleocapsid protein from <Emphasis Type="Italic">Tomato spotted wilt virus</Emphasis> for promoting RNA-mediated cross-protection using the <Emphasis Type="Italic">Potato virus X</Emphasis> vector system

Virus interactions between Tomato spotted wilt virus (TSWV) and Potato virus X (PVX) containing the nucleocapsid protein (N) gene sequences were examined to evaluate the capacity of the N gene sequences from TSWV to promote RNA-mediated cross-protection. Plants simultaneously inoculated with TSWV and PVX containing the 3 96bp of the N gene were highly resistant to TSWV infection, whereas no such resistance was observed in plants inoculated with TSWV and PVX containing the 5 96bp. These results suggest that the 3 portion of the N gene has a higher capacity for promoting RNA-mediated cross-protection of TSWV.     

Isolation of exfoliative toxin from Staphylococcus intermedius and its local toxicity in dogs

A rounding effect was demonstrated in cultured cells inoculated with the culture filtrates (CFs) of 60 strains of Staphylococcus intermedius derived from dogs affected with pyoderma. Exfoliative toxin (ET)-like toxin (ETLT) was isolated from the CF of S. intermedius strain D-52, which exhibited strong rounding activity and then was purified by gel filtration on a Sephadex G-75 column, and by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The ETLT caused exfoliation in 1-day-old chickens, suckling Syrian hamsters, and dogs, but not in suckling mice. The ETLT was serologically different from exfoliative toxin A (ETA), exfoliative toxin B (ETB), exfoliative toxin C (ETC), S. hyicus exfoliative toxin A (SHETA), and SHETB, as shown by Western blot analysis. The molecular weight of the ETLT was estimated at 30 kDa by SDS-PAGE. In the present study, we propose the ETLT was a novel type of ET, S. intermedius exfoliative toxin (SIET).     

Cloning of the gene coding for Staphylococcus intermedius exfoliative toxin and its expression in Escherichia coli

An exfoliative toxin (SIET)-producing strain (D-52) of Staphylococcus intermedius derived from canine pyoderma did not possess large plasmids. Therefore, the gene coding for SIET was considered to be located on the chromosomal DNA. The SIET gene was cloned from the chromosomal DNA of S. intermedius and was expressed in Escherichia coli. The nucleotide sequence of the SIET gene consists of a coding region of 990 bp specifying a polypeptide of 330 amino acid residues, which included a putative 42-residue signal sequence.     

Estimating stand structure using digitalized aerial photography

This study estimates the structure of a forest stand using high-resolution data from digitized aerial photography. The study area was conducted on the fifteen plots with the size of 20 m × 20 m or 15 m × 15 m taken as samples of sugi (Cryptomeria japonica D. Don) stands. The stand factor was investigated based on its relation with the digitalized number (DN) on the black and white aerial ortho photos (scale 1:5,000, taken in 1995). We analyzed various stand structure factors and the distribution of DN from the image data using the Weibull function, which comforms well to every shape of distributions. Using the Weibull distribution, a significant negative correlation was observed between the quantity of stand factors (Mean DBH and the stand volume) and the distribution parameterc of DN. A significant positive correlation was also observed between the distribution parameterc of the stand factor (DBH, height and volume) and the distribution parameterc of DN.     

Developmental and tissue-specific expression of CHS1 from Plutella xylostella and its response to chlorfluazuron

The cDNA of chitin synthase-1 gene of Plutella xylostella (PxCHS1) was characterized and expression patterns of the two splice variants PxCHS1A and PxCHS1B were investigated in various developmental stages and in major body tissues by RT-PCR and real-time quantitative PCR (qPCR). The PxCHS1 cDNA was 5461 bp in length with an open reading frame of 4701 bp that encoded a putative protein of 1567 amino acids with predicted molecular mass of 179 kDa. The two splice variants were expressed from the mutually exclusive exons which were same in size (177 bp) but showed only 66% identity at the nucleotide level. Both splice variants were expressed in all developmental stages. The qPCR data suggested an uneven expression of the two variants in the body where expression of PxCHS1A was 3.7-fold higher than that of PxCHS1B. The expression of PxCHS1A was 1.5-fold higher in the head than the body whereas in case of PxCHS1B the difference between head and body was 6.3-fold. Chlorfluazuron did not change the expression of PxCHS1 in larvae.     

Possibility of quantitative assessment of the contribution of paddy irrigation and caldera lakes to river water in Bali Island using water isotopic physics

Paddy and Water Environment - This study aims to investigate a possibility of quantitative assessment of the relationship between return flow from paddy fields and river regime by using hydrogen-...