“三定”栽培对双季超级稻养分吸收积累及氮肥利用率的影响

为探讨南方双季超级稻对氮、磷、钾养分的吸收积累及利用规律,于2008—2010年在湖南长沙和浏阳以超级早稻陆两优996、陵两优268和超级晚稻丰源优299、天优华占为材料进行大田定位试验,比较了“三定”栽培、免耕摆栽和传统栽培条件下双季超级稻不同生育期植株体内氮、磷、钾吸收积累特点及氮肥利用率。与传统栽培相比,“三定”栽培双季超级稻生长前期(分蘖中期)氮、磷、钾的吸收量较低,幼穗分化期差异甚小,而齐穗期(早季平均为10.71、2.23和11.82 g m^-2,晚季平均为12.25、2.69和16.37 g m^-2)和成熟期(早季平均为13.61、3.01和13.71 g m^-2,晚季平均为17.16、3.31和18.31 g m^-2)较高;氮肥的偏生产力(平均为53.40 kg kg^-1)、吸收利用率(平均为55.98%)、农学利用率(平均为22.27 kg kg^-1)较高,分别提高29.00%、88.92%和46.67%。免耕摆栽双季超级稻不同生育时期氮、磷、钾的吸收特点与“三定”栽培相似,但其氮肥的偏生产力、吸收利用率和农学利用率(平均为50.24 kg kg^-1、52.75%、19.33 kg kg^-1)分别比“三定”栽培降低6.29%、6.12%和15.19%。由此可见,双季超级稻生产采用“三定”栽培技术有利于提高氮肥利用率。     

“三定”栽培对双季超级稻产量形成及生理特性的影响

为探讨南方双季稻区超级稻高产栽培技术,于2008—2010年在湖南长沙和浏阳以超级早稻陆两优996、陵两优268和超级晚稻天优华占、丰源优299为材料进行大田定位试验,比较了“三定”栽培、免耕摆栽和传统栽培下双季超级稻的产量形成特点和生理特性。与传统栽培相比,“三定”栽培齐穗期的颖花伤流量、根系氧化力、根冠比、叶面积指数及籽粒结实期剑叶的光合速率较高,齐穗后剑叶SPAD值下降缓慢、干物质积累量大,有效穗数和每穗粒数多,早季平均产量为7.18 t hm^-2,增产11.68%,晚季平均产量为8.39 t hm^-2,增产7.41%;免耕摆栽干物质积累量大、有效穗数多,但其收获指数、每穗粒数和结实率居劣势,使其单季增产效果不显著。由此可见,南方双季超级稻在“三定”栽培下后期生理优势明显,产量构成因子协调,增产效果显著。     

Glutathione functions on physiological characters to increase copper-induced corn production

Glutathione (GSH) abundantly presents in plant and affects plants growth and development. To justify if GSH affects copper (Cu)-induced corn production, photosynthesis (Pn) rate, and photosynthetically active radiation (PAR), chlorophyll (Chl) content and Chl fluorescence, relative water content (RWC) and yields were evaluated. Different Cu concentrations (0, 0.2, 1.5 and 3.0 ppm of Zn) with or without 100 µm of N-acetyl cysteine (NAC) were arranged as completely randomize design with 5 replications. Results showed that both NAC and Cu affected plant height and leaf numbers. Copper reduced Pn rate, and PAR and increased RWC but no effect was observed on Chl content and Chl fluorescence in leaves. On the other hand, NAC application increased Pn, PAR, Chl parameters regardless of Cu treatment. In the presence of 1.5 ppm of Cu, corn plants showed improve yield and cob length irrespective to NAC treatment. Taken together, this study suggests that NAC might improve some physiological functions in plants to enhance Cu-induced corn production.     

Analysis of methanogenic archaeal communities of rumen fluid and rumen particles from Korean black goats

Molecular diversity of methanogens in the rumen of Korean black goats was investigated with 16S rRNA gene clone libraries using methanogen‐specific primers. The libraries were composed of rumen fluid‐associated methanogens (FAM) and rumen particle‐associated methanogens (PAM) from rumen‐fistulated Korean black goats. Among the 141 clones of the FAM library, the sequences were mostly related to two phyla, the Methanobacteriaceae family (77.3%) and the Thermoplasmatales family (22.7%); and among the 68 clones of the PAM library, sequences were also mainly clustered in the two phyla, the Thermoplasmatales family (63.24%) and the Methanobacteriaceae family (35.29%). Most of the sequenced clones in the two libraries were closely related to uncultured methanogenic archaeon. Quantitative real‐time PCR revealed that PAM (8.97 log 10) had significantly higher (P < 0.01) density of methanogens by the methanogenic 16S rRNA gene copies than FAM (7.57 log 10). The two clone libraries also showed difference in Shannon index (FAM library 1.70 and PAM library 1.59) and Chao 1 estimator (FAM library 18 and PAM library 17 operational taxonomic units). Apparent differences found in the microbial community from the two 16S rRNA gene libraries could be a result of such factors as the chemical and physical nature of the target material surface, types or component of diets, the interaction between the methanogens and other microbes, and age of the experimental goats.     

Development of on-line measurement system of bulk density based on on-line measured draught, depth and soil moisture content

On-line measurement of soil compaction is needed for site specific tillage management. The soil bulk density (ρ) indicating soil compaction was measured on-line by means of a developed compaction sensor system that comprised several sensors for on-line measurement of the draught (D) of a soil cutting tool (subsoiler), the soil cutting depth (d) and the soil moisture content (w). The subsoiler D was measured with a single shear beam load cell, whereas d was measured with a wheel gauge that consisted of a swinging arm metal wheel and a linear variable differential transducer (LVDT). The soil w was measured with a near infrared fibre-type spectrophotometer sensor. These on-line three measured parameters were used to calculate ρ, by utilising a hybrid numerical–statistical mathematical model developed in a previous study. Punctual kriging was performed using the variogram estimation and spatial prediction with error (VESPER) 1.6 software to develop the field maps of ρ, soil w, subsoiler d and D, based on 10 m × 10 m grid. To verify the on-line measured ρ map, this map was compared with the map measured by the conventional core sampling method.

The spherical semivariogram models, providing the best fit for all properties was used for kriging of different maps. Maps developed showed that no clear correlation could be detected between different parameters measured and subsoiler D. However, the D value was smaller at shallow penetration d, whereas large D coincided with large ρ values at few positions in the field. Maps of ρ measured with the core sampling and on-line methods were similar, with correlation coefficient (r) and the standard error values of 0.75 and 0.054 Mg m⁻³, respectively. On-line measured ρ exhibited larger errors at very dry zones. The normal distribution of the ρ error between the two different measurement methods showed that about 72% of the errors were less than 0.05 Mg m⁻³ in absolute values. However, the overall mean error of on-line measured ρ was of a small value of 2.3%, which ensures the method accuracy for on-line measurement of ρ. Measurement under very dry conditions should be minimised, because it can lead to a relatively large error, and hence, compacted zones at dry zones cannot be detected correctly.     

Boron-Calcium Synergically Alleviates Aluminum Toxicity in Wheat Plants (Triticum aestivum L.)

The effects of B and Ca treatments on root growth, nutrient localization and cell wall properties in wheat ( Triticum aestivum L.) plants with and without Al stress were investigated. Seedlings were grown hydroponically in a complete nutrient solution for 7 d and then treated with B (0, 40 μM), Ca (0, 2,500 μM), and Al (0, 100 μM) in a 500 μM CaCl₂ solution for 8 d. The cell wall materials (CWM) were extracted with a phenol: acetic acid: water (2:1:1 w/v/v) solution and used for subsequent pectin extraction with trans -1,2-diami-nocyclohexane- N,N,N,N -tetraacetic acid (CDTA) and Na₂CO₃ solutions. Boron, Ca, and B + Ca treatments enhanced root growth by 19.5, 15.2, and 27.2%, respectively, compared to the control (pH 4.5). Calcium and B+Ca treatments enhanced root growth with Al stress by 43 and 54%, respectively, while B did not exert any effect. The amounts of CWM and pectin per unit of root fresh weight increased by Al treatment, whereas the Ca and B+Ca treatments slightly reduced the contents of these components. Seventy-four percent of total B, 69% of total Ca, and 85% of total Al were located in the cell wall in the B, Ca, and Al treatments, respectively and 32% of total B, 33% of total Ca, and 33% of total Al were located in the CDTA-soluble and Na₂CO₃-soluble pectin fractions. A more conspicuous localization of B was observed in the presence of Al. Aluminum treatment markedly decreased the Ca content in the cell wall as well as pectin fractions, mainly in the case of the CDTA-soluble pectin fraction. Boron + Ca treatment decreased the Al content in the cell wall and pectin fractions compared to the Ca treatment alone in the presence of Al. It is concluded that the B+Ca treatment enhanced root growth and, B and Ca uptake, and helped to maintain a normal B and Ca metabolism in the cell walls even in the presence of Al.     

Optimization of Compatible Mixed Cultures for Liquid State Bioconversion of Municipal Wastewater Sludge

The filamentous fungal strains such as Penicillium corylophilum (P), Aspergillus niger (A), Trichoderma harzianum (T) and Phanerochaete chrysosporium (PC) isolated from its relevant sources (wastewater, sewage sludge and sludge cake) were selected for compatible/incompatible mixed cultures. Six combinations of P. corylophilum and A. niger (P/A); P. corylophilum and P. chrysosporium (P/PC); P. corylophilum and T. harzianum (P/T); A. niger and T. harzianum (A/T); A. niger and P. chrysosporium (A/PC); T. harzianum and P. chrysosporium (T/PC) were used to evaluate their potential performance as compatible/incompatible mixed culture for the treatment of municipal wastewater sludge in a bioconversion process. The results of the present study showed that the combinations of P/A, P/PC and A/PC showed compatible growth and the rest of the combinations (P/T, A/T and T/PC) were incompatible cultures. A maximum production of dry biomass and dry filter cake were recorded in the compatible mixed culture of P. corylophilum and A. niger (P/A). A maximum reduction of COD (90%) and a decreased filtration time of treated sludge was observed in the case of P/A microbial mixed culture. The pH value was also affected by the fungal cultures. Effective results were observed by using microbial mixed culture after four days of treatment compared to other treatments (2 and 6 days).     

Earthworm casts form stable aggregates in physically degraded soils

Topsoils affected by surface mining suffer severe physical degradation and lose most of their earthworm populations. After mining, replaced soils are planted to grassland and managed to improve soil structure. Earthworm inoculation into selected restored areas produced populations similar to those of undisturbed soils within 3 years. Soil properties in inoculated areas were compared with those of controls to evaluate the contribution of casts to bulk soil aggregation, and soil organic matter and root content responses to earthworm activity. Crumb porosity and coarse particle content were measured in water-stable macro-aggregates and earthworm casts to establish whether aggregates were formed by earthworms. Over a 5- to 6-year period, inoculation increased stable aggregation (>2 μm, >60 μm and >3 mm), even at 0- to 5-cm depth where it reduced soil organic matter content. Productivity and root content were also increased by inoculation; roots and organic matter were re-distributed to greater depth. Crumb porosity decreased with casts > aggregates (inoculated plots) > aggregates (control plots). Coarse particle content increased with casts < aggregates (inoculated plots) < aggregates (control plots). Coarse particle and porosity data were consistent with much of the newly aggregated soil being processed and formed by earthworms as casts. Whilst levels of soil organic matter were often closely associated with percentage stable aggregation, root content showed weaker associations. Aggregation percentage was most closely associated with abundance of Aporrectodea longa, although at particular depths significant correlations were also obtained for Aporrectodea caliginosa and Lumbricus terrestris. Results suggest that earthworms, rather than plant roots, initiate aggregation in severely degraded grassland soils.     

Development and Characterization of Novel Polymorphic Microsatellite Markers for Tapinoma indicum (Hymenoptera: Formicidae)

Tapinoma indicum (Forel) (Hymenoptera: Formicidae) is a nuisance pest in Asia countries. However, studies on T. indicum are limited, especially in the field of molecular biology, to investigate the species characteristic at the molecular level. This paper aims to provide valuable genetic markers as tools with which to study the T. indicum population. In this study, a total of 143,998 microsatellite markers were developed based on the 2.61 × 10⁶ microsatellites isolated from T. indicum genomic DNA sequences. Fifty selected microsatellite markers were amplified with varying numbers of alleles ranging from 0 to 19. Seven out of fifty microsatellite markers were characterized for polymorphism with the Hardy–Weinberg equilibrium (HWE) and linkage disequilibrium (LD) analysis. All seven microsatellite markers demonstrated a high polymorphic information content (PIC) value ranging from 0.87 to 0.93, with a mean value of 0.90. There is no evidence of scoring errors caused by stutter peaks, no large allele dropout, and no linkage disequilibrium among the seven loci; although loci Ti-Tr04, Ti-Tr09, Ti-Te04, Ti-Te13, and Ti-Pe5 showed signs of null alleles and deviation from the HWE due to excessive homozygosity. In conclusion, a significant amount of microsatellite markers was developed from the data set of next-generation sequencing, and seven of microsatellite markers were validated as informative genetic markers that can be utilized to study the T. indicum population.