甘肃省典型土壤有益微生物区系动态

以甘肃省金昌高钙土、民勤沙漠土、武威灌漠土、定西黄绵土为对象,对耕层土壤和当地主要种植作物根际和土体的自生固氮菌、解磷菌、解钾菌数量进行平板涂抹法测定。结果表明:各土壤有益微生物数量均在108~109数量级范围内变化,其中武威灌漠土、定西黄绵土中各有益微生物数量无论是播种前还是在作物花期均明显高于金昌高钙土与民勤沙漠土,而且各作物根际有益微生物数量均明显高于土体6.12%~161.66%。     

不同氮水平下三种固氮菌剂对油菜及土壤中氮素的影响

通过在油菜盆栽试验中施加不同浓度的尿素和三种不同的固氮菌剂,比较分析了油菜和土壤中氮素的变化,结果表明:在施加尿素为2g/kg的范围内,土壤和植物中的氮素会随着尿素施入量的增多而增多;并且从马铃薯增产菌剂中分离出来的固氮菌比从生根旺菌肥和玉米复合微生物菌剂中分离出来的菌肥在施氮量适中的情况下固氮能力比较强。可为固氮菌肥的合理有效施用与氮肥的优化配比及探求作物高产优质的生物调控提供理论依据。     

Field efficiency of biofertilizers on the growth of okra (Abelmoschus esculentus [(L.) Moench])

An experiment was carried out at the Farm of the Department of Crop Botany, Bangladesh Agricultural University, Mymensingh from March to July, 2001 to investigate the effect of biofertilizers on morpho‐physiological characters of okra. The experiment was laid out in a randomized complete block design with four replications. There were nine treatments such as T₀ (control), T₁ (Azotobacter biofertilizer), T₂ (Azospirillum. biofertilizer), T₃ (Azotobacter + Azospirillum. biofertilizers), T₄ (Azotobacter + Cowdung 5 t ha^–1), T₅ (Azospirillum + 5 t ha^–1 cowdung), T₆ (Azotobacter + Azospirillum + 5 t ha^–1 cowdung), T₇ (5 t ha^–1 cowdung), and T₈ (60 % N). The experimental results revealed significant variations among the treatments in respect of morphological characters, e.g. plant height, number of leaves per plant, stem base diameter, tap root length, and physiological characters like root dry weight, leaf area index, and crop growth rate. Number of leaves per plant, stem base diameter, root length, root dry weight, leaf area index, and crop growth rate were larger in T₄, T₅, T₆, and T₈ than the others. In all the parameters, T₈ gave the similar result with biofertilizers in combination with cowdung treatments, and T₇ was identical with T₀ (control). These experimental results revealed that morpho‐physiological characters of okra could be modified by the application of biofertilizer + cowdung. However, biofertilizers + cowdung treatments were comparable to T₈ (60 % N) in this study. This suggests that T₄ or T₆ or T₅ were more benificial in environmentally friendly okra cultivation and may be used as an alternative of inorganic N by saving cost of production and sustaining productivity.     

Synergistic effects of the inoculation with nitrogen‐fixing and phosphate‐solubilizing rhizobacteria on the performance of field‐grown chickpea

The synergistic effects of nitrogen‐fixing and phosphate‐solubilizing rhizobacteria on plant growth, yield, grain protein, and nutrient uptake of chickpea plants were determined in a sandy clay‐loam soil. Legume grain yield and concentration and uptake of nitrogen (N) and phosphorus (P) were significantly increased as a result of co‐inoculation with Mesorhizobium and P‐solubilizing Pseudomonas and Bacillus spp. The inoculation with M. ciceri RC4 + A. chroococuum A10 + Bacillus PSB9 tripled the seed yield and resulted in highest grain protein (295 mg g^–1) at 145 d after sowing (DAS). An 8% increase in P concentration above the uninoculated control was observed in case of a single inoculation with Pseudomonas PSB 5, while the P uptake was highest (2.14‐fold above the uninoculated control) with a combined inoculation with [M. ciceri RC4 + A. chroococcum A10 + Bacillus PSB 9] at 145 DAS. The highest N concentration and N uptake at 145 DAS (81% and 16% above the uninoculated control, respectively) were observed with the triple inoculation of [M. ciceri RC4 + A. chroococcum A10 + Pseudomonas PSB 5). These findings show that multiple inoculations with rhizospheric microorganisms can promote plant growth and grain yield and increase concentrations and uptake of N and P by field‐grown chickpea.     

固氮菌孢囊的诱导及其超微结构

用正丁醇诱导固氮菌孢囊形成5d,维氏固氮菌(Azotobactervinelandii)有98%的细胞形成孢囊,圆褐固氮菌(Azotobacterchroococcus)有91%的细胞形成孢囊.固氮菌孢囊为球形或卵圆形,直径1.2～1.5μm.其结构可明显分辨成三部分:中心体,内壁层和外壁层.成熟孢囊的中心体内含有聚β-羟基丁酸盐颗粒.内壁层密度小而宽,外壁层为紧密多层膜片状结构.     

营养成分对维氏固氮菌合成褐藻酸钠的影响

报道了各种营养成分对维氏固氮菌(Azotobacter vinelandii)产褐藻酸钠及对褐藻酸钠中甘露糖醛酸与古洛糖醛酸比值(M/G)的影响。认为调节培养基中的磷酸氢二钾、酵母膏至最佳浓度,可使蔗糖合成褐藻酸钠的转化率达40％以上。培养基中磷酸氢二钾、钼酸钠、硫酸钙的浓度显著影响细菌褐藻酸钠的M/G值。     

Interactive Effect of Rhizotrophic Microorganisms on Growth,Yield, and Nutrient Uptake of Wheat

The interactive effect of rhizotrophic microorganisms on growth, yield, and nutrient uptake of wheat (Triticum aestivum L.) was determined in a pot experiment using sterilized soil deficient in available phosphorus (P). Positive effect on plant vigor, nutrient uptake, and yield in wheat plants was recorded in the treatment receiving mixed inoculum of nitrogen-fixing Azotobacter chroococcum + phosphate solubilizing microorganism (PSM) Pseudomonas striata + arbuscular mycorrhizal (AM) fungus Glomus fasciculatum. The available P status of the soil improved significantly (P ≤ 0.5) following triple inoculation with A. chroococcum, P. striata, and G. fasciculatum. The residual nitrogen (N) content of the soil did not change appreciably among the treatments. Addition of Penicillium variable to single- or double-inoculation treatments negatively affected the measured parameters. The population of A. chroococcum, PSM, percentage root infection, and spore density of the AM fungus in inoculated treatments increased at 80 days of wheat growth. The present finding showed that rhizotrophic microorganisms can interact positively in promoting plant growth, as well as N and P uptake, of wheat plants, leading to improved yield.     

Adsorption of silica in river waters by soils in central Chile

The adsorption of the silica in water by soils was investigated using principal river waters and soils collected in central Chile from about 34° to 41° south latitude. The adsorption of silica in water (y) was linearly proportional to the silica concentration in river waters (x) as shown by the following equation:

y=bx-a

where a and b were constants being subject to the nature of the soils. The silica contentration in river waters appeared to relate closely to the rocks in the catchment area. and was high in rivers from volcanic ash areas. However, the salt concentration had no correlation with the silica concentration, and tended to lower to the southward with an increase in annual precipitation and a decrease in annual mean temperature. Sulphate appreciably lowered the adsorption of silica by soils, although chloride and nitrate had little effect on the adsorption. The a-value, dissolution of silica in pure water, was the largest in paddy and alluvial soils, and both the a- and b-values were less in surface soils .in comparison with those of lower horizons. Soils caused neither adsorption nor dissolution of silica at a certain silica concentration. This silica zero adsorption concentration differed greatly from soil to soil, and the largest value which was observed in the surface soil of an irrigated paddy soil was so large that it could not adsorb silica from any river water in the central Chile. In contrast to this soil, an imogolitic subsoil of an Ando soil exhibited the highest adsorption concentration, i.e. it was possible to adsorb silica from every river water in the central Chile. Humus seemed to protect soil silica from dissolution and at the same time to prevent adsorption of silica by soils. Allophanic colloids were labile in water without humic-material, readily releasing silica into the water.     

水稻根际固氮菌促生特性评价

利用半固体培养基和土壤栽培经水稻特异性根际固氮菌处理的水稻幼苗,发现固氮菌属(Azotobacterspp.)菌株R-N00、R-N1110和R-N1112具有较强的促生能力。半固体培养基栽培获得接种3株菌株的水稻幼苗干重分别提高16.60%、9.23%和9.37%,根干重分别提高38.00%、30.00%和55.00%;土壤栽培获得接种菌株的水稻幼苗干重分别提高93.25%、90.18%和97.21%,根干重分别提高71.25%、72.21%和74.92%。这3株菌的固氮能力分别为13.37、11.93和13.57 mg.L-1;合成铁载体能力均达到5+;分泌吲哚乙酸分别为6.79、8.60和3.39 mg.L-1;溶磷能力分别为41.63、37.76和39.78 mg.L-1。结果表明,水稻根际促生菌的各种促生生理活性共同作用促进水稻幼苗生长,为高效生物肥料的研究提供参考。