Microbial mineralization of organic nitrogen into nitrate to allow the use of organic fertilizer in hydroponics

Hydroponics is an excellent technique for the cultivation of vegetable crops and other plants, but organic fertilizers cannot be used in conventional hydroponic systems, which generally use only inorganic fertilizers, because organic compounds in the hydroponic solutions generally have phytotoxic effects that lead to poor plant growth. Few microorganisms are present in hydroponic solutions to mineralize the organic compounds into inorganic nutrients. In this article a novel and practical hydroponic culture method that uses microorganisms to degrade organic fertilizer in the hydroponic solution has been developed. Soil microorganisms were cultured by regulating the amounts of organic fertilizer and inoculum, with moderate aeration. The microorganisms mineralized organic nitrogen via ammonification and nitrification into nitrate at an efficiency of 97.6%. The culture solution containing the microorganisms was usable as a hydroponic solution, and organic fertilizer could be directly added to it during vegetable cultivation. Vegetables grew well in the organic hydroponic system. Organic hydroponics based on this method is therefore a practical tool for the utilization of organic sources of fertilizer.     

Effect of rice variety on methane emission from an Indonesian paddy field

Variations in CH₄ emission from a Sumatra paddy field in which 8 popular modern varieties in Indonesia were grown were compared in the 1994/1995 rainy season. Total amounts of CH₄ emitted during the period of rice growth were in the ranges of 32.6-41.7 and 51.3–64.6 g CH₄ m^-2 for the plots amended with chemical fertilizer only and those amended with both rice straw and chemical fertilizer, respectively. The mean CH₄ emission rate was highest in the plot with the variety Bengawan solo and lowest in the plots with the varieties Atomita-4 and Way seputih among the plots which received chemical fertilizer, while highest in the plot with Way seputih and lowest in the plot with Bengawan solo among the plots amended with both rice straw and chemical fertilizer. The increase in the mean CH₄ emission rates by rice straw application was higher for the plots planted with Way seputih (1.98 times) and Atomita-4 (1.77 times) than for the plots with Bengawan solo (1.23 times) and IR-64 (1.35 times). The plots with Walanai and Cisanggarung recorded intermediate mean emission rates and the increase in CH₄ emission by rice straw application was also intermediate (1.57–1.64 times). It was noteworthy that Way seputih and Atomita-4 were derived from the variety Cisadane, Bengawan solo and IR-64 from the variety IR-54, and Walanai and Cisanggarung from the varieties IR-36 and Pelita 1-1, respectively.

The amounts of CH. emitted for 1 kg grain production ranged from 53 (Atomita-4) to 74 (Kapuas and Walanai) and from 89-93 (IR-64, Bengawan solo, and Atomita-4) to 121 (Kapuas) g CH₄ kg^-1 of grain for the plots amended with chemical fertilizer and those amended with rice straw and chemical fertilizer, respectively.     

Contribution of charcoal to short-term nutrient dynamics after surface fire in the humus layer of a dwarf bamboo-dominated forest

Ecological function of charcoal has been mainly investigated by adding charcoal to soil, which is not fully adequate to understand in situ the role in fire-prone forest ecosystem. To determine in situ effects of charcoal on ecosystem functions, such as nutrient availability, we conducted an experimental burning in a Japanese white birch forest with dense coverage of dwarf bamboo in the understory with or without removal of charcoal. Ammonium-N in the remaining humus layer increased immediately after the burning, but decreased to the level of unburnt plots within 1?month of the burning. Removal of charcoal had no significant effect on the NH₄ ⁺-N dynamics. Although burning did not affect NO₃ ^?-N dynamics during the sampling period, charcoal removal led to a slight increase in NO₃ ^?-N. The available P increased immediately after the burning, but then fell at 1?month after burning. Charcoal inhibited the available P depletion and prolonged the high availability of P. Greater availability of P might be due to the adsorption of phosphate in charcoal pores. Exchangeable Ca and Mg increased gradually; charcoal appeared to extend the period of higher concentration of exchangeable Ca and Mg. Charcoal deriving from fire is a key factor in influencing available nutrient in the humus layer of post-fire forests.     

Origin of waxy common millet, Panicum miliaceum L. in Japan

We developed PCR-based markers for genotyping Waxy genes in common millet (Panicum miliaceum L.) and proposed a new hypothesis on the origin and dispersal of waxy type of Japanese landraces. I₂-K staining indicated that almost all the Japanese landraces had waxy endosperm. Based on the PCR and dCAPs analyses of two waxy loci on different genomes we concluded that there were at least two possible lineages in Asian continent that had independent dispersal pathways into Japan. Most Japanese common millet had the similar genotypes with those in Korean Peninsula but a few particularly from northern part of Japan had common genotypes in northeastern China and Primorskaya Province of Russia.     

Novel prediction method of beer foam stability using protein Z, barley dimeric alpha-amylase inhibitor-1 (BDAI-1) and yeast thioredoxin

Foam stability is an important quality trait of beer. Our previous results of two-dimensional gel electrophoresis (2DE) analyses of beer proteins implied a relationship between barley dimeric alpha-amylase inhibitor-1 (BDAI-1) and beer foam stability as judged by the NIBEM-T analyzer. To develop a novel prediction method of beer foam stability under different conditions of barley cultivar and malt modification, multiple linear regression analysis was applied. The spot intensities of major beer proteins on 2DE gel were quantified and used as explanatory variables. The foam stabilities of 25 beer samples each brewed from malt with different malt modification in one of the three cultivars (cultivars A, B, and C) were explained by the spot intensities of BDAI-1 at the 5% significance level ( r = 0.421). Furthermore, two other major protein spots (b0 and b5) were observed on the 2DE gels of Japanese commercial beer samples with different foam stability. Then, multiple regression for foam stability was calculated using these three spot intensities as explanatory variables. As a result, 72.1% of the beer foam stability in 25 beer samples was explained by a novel multiple regression equation calculated using spot b0 and BDAI-1 as positive explanatory variables and spot b5 as a negative variable. To verify the validity of the multiple regression equation and the explanatory variables, the beer foam stability in practical beer samples was analyzed. As a result, 81.5% of the beer foam stability in 10 Japanese commercial beer samples was also explained by using spot b0 and BDAI-1 as positive explanatory variables and spot b5 as a negative variable. Mass spectrometry analyses followed by database searches revealed that protein spots b0 and b5 were identified as protein Z originated from barley and thioredoxin originated from yeast, respectively. These results confirm that BDAI-1 and protein Z are foam-positive factors and identify yeast thioredoxin as a possible novel foam-negative factor.     

Effect of fungicide thiram on microbial communities of rice seed surface estimated by culture-dependent and culture-independent (PCR-RFLP) methods

Coating of rice seeds with fungicide Thiram improved the seed germination capability over a long period of time (11 weeks) under low temperature conditions (4 and 8°C), which simulated the sowing of rice seeds in the winter season (the farmer's slack season). To analyze the effect of Thiram on the community structure of microorganisms on the rice seed surface, culture-dependent and culture-independent (PCR-RFLP) methods were applied. PCR-RFLP patterns of 16S rDNA showed that the bacterial communities on the rice seed surface were different between coated and uncoated treatments under 8°C conditions, but that they were very similar under 4°C conditions. PCR-RFLP patterns of 18S rDNA revealed the remarkable effect of Thiram on the fungal community structure under both 4 and 8°C conditions. Although the fungal communities were quite different between coated and uncoated seeds at the beginning of incubation, the fungal communities on the coated seed surface became similar to those of uncoated seeds along with the duration of the incubation period. As the dominance percentage of Fusarium spp. among the isolates increased with the duration of the incubation period for both coated and uncoated seeds, Fusarium was considered to be a responsible for the poor germination of rice seeds that were sown in the winter season.     

Effect of rice straw application on CH4 emission from paddy fields

The effect of rice straw (RS) incorporated at the time of plowing in the previous cr–p season on CH₄ emission from rice paddies was investigated in a pot experiment. Rice straw that incorporated just before transplanting of rice seedlings (June) into a paddy field was collected after the harvest (October) and at the beginning of the next cropping period (May). Methane emission rates from the rice-planted pots with the application of fresh RS, RS collected in October. and RS collected in Mayas well as the pots without RS application were measured using the chamber method. The composition of organic constituents in the three kinds of RS was estimated by the proximate analysis. The cumulative amount of CH₄ emitted during the first 50–d period was lower in the order of the pots with RS collected in May, pots with RS collected in October, and pots with fresh RS. The cumulative amount of CH₄ emitted throughout the rice growth period from the pots with fresh RS and with RS collected in October was significantly larger while that from the pots with RS collected in May did not differ statistically compared with the total CH₄ emission from the pots without RS. These results suggested that there was an overall decrease in the amount of organic constituents in RS based on the large differences in T-C content and similar composition of organic constituents between the fresh RS and RS collected in May. Significant effect of RS continuously applied during the previous cropping period on the increase in CH₄ emission was discussed.     

Identification of reaction products of acylated anthocyanins from red radish with peroxyl radicals

Red radish anthocyanin extract, which consists of 12 known acylated anthocyanins, was reacted with 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH) to generate peroxyl radicals under acidic pH conditions at 37 degrees C. The reaction products were isolated using preparative HPLC, and their chemical structures were determined to be p-hydroxybenzoic acid (1), 6-O-(E)-p-coumaroyl-2-O-beta-d- glucopyranosyl-alpha-d-glucopyranoside (3), p-coumaric acid (4), 6-O-(E)-feruloyl-2-O-beta-d-glucopyranosyl-alpha-d-glucopyranoside (5), and ferulic acid (6). Some products were not identified. HPLC analyses of the mixture of acylated pelargonidin isolated from red radish and AAPH revealed that the acylated pelargonidins possess the radical scavenging ability on some common sites even if the characteristics of the intramolecular acyl units are different. Degradation rates of acylated pelargonidins and the formation rates of the resulting reaction products were found to be quite different.     

Mass and local topography measurements of Itokawa by Hayabusa

The ranging instrument aboard the Hayabusa spacecraft measured the surface topography of asteroid 25143 Itokawa and its mass. A typical rough area is similar in roughness to debris located on the interior wall of a large crater on asteroid 433 Eros, which suggests a surface structure on Itokawa similar to crater ejecta on Eros. The mass of Itokawa was estimated as (3.58 +/- 0.18) x 10(10) kilograms, implying a bulk density of (1.95 +/- 0.14) grams per cubic centimeter for a volume of (1.84 +/- 0.09) x 10(7) cubic meters and a bulk porosity of approximately 40%, which is similar to that of angular sands, when assuming an LL (low iron chondritic) meteorite composition. Combined with surface observations, these data indicate that Itokawa is the first subkilometer-sized small asteroid showing a rubble-pile body rather than a solid monolithic asteroid.