稻田固氮解磷解钾菌筛选及其复合菌剂对土壤培肥作用

用固氮、解磷、解钾培养基,分别从稻田土壤中分离获得9个固氮菌株(A1-A9)、7个解磷菌株(B1-B7)和6个解钾菌株(C1-C6)。对各菌株固氮、解磷、解钾能力及水稻促生效果分析表明,最突出菌株分别为A5、B2、C5;各菌株等比例混合组成复合菌剂接入灭菌稻田土壤,30 d后可使土壤总氮、有效磷、速效钾分别增加21.32%、32.17%、45.57%;初步鉴定各菌株分别为固氮菌属(Azotobacter sp.)、假单胞菌属(Pseudomonas sp.)和芽孢杆菌属(Bacillus sp.)。复合菌剂处理稻田土壤,水稻苗高、鲜重、干重及植株全氮、全磷、全钾显著优于对照组,说明筛选菌株可在稻田土壤氮、磷、钾转换及培肥过程中起重要作用。     

表达大肠杆菌K99重组干酪乳杆菌口服免疫小鼠的免疫保护性研究

利用千酪乳杆菌(Lactobacillus casei)作为抗原传递系统来刺激机体产生黏膜免疫反应,从而研制有效的黏膜疫苗预防产肠毒素性大肠杆菌(ETEC)的感染.用PCR方法扩增ETEC K99基因,克隆到L.casei细胞表面表达载体pLA中,构建了重组表达载体pLA.K99,并将其电转化至L.casei中,在MRS培养基中培养后,经SDS-PAGE、western blot检测目的蛋白的表达,间接免疫荧光分析及流式细胞术检测外源蛋白展示到菌体表面.将重组菌及空质粒菌株分别口服接种SPF级BALB/c小鼠.采集血液样品测定小鼠产生抗K99的特异性IgG,收集小鼠肺部、肠道、阴道冲洗液及粪便样品测定小鼠产生的抗K99的特异性sIgA,并对小鼠进行攻毒保护性试验,免疫组保护率在83%以上,对照组则全部死亡.     

Fluctuations in soil test values for potassium as influenced by time of sampling

Abstract

Soil samples were taken at frequent intervals in 1975 and 1976 from a factorial set of lime ‐K treatments initiated in December 1970 to determine the effect time of sampling has on K soil test values. Previous work at this site had shown wide fluctuations in K soil test values due to sample time thus necessitating a more detailed study than was previously made. Such information is necessary if accurate K fertilizer recommendations are to be made. Samples from 28 unfertilized plots showed that months of sampling significantly affected K soil test values. Soil test values for K were highest in late May and declined as the growing season progressed, remaining low until the relatively higher exchangeable K was re‐established the following spring.

Disregard for this phenomenon could result in inaccurate recommendations for K fertilizer.     

Yield Quality Parameters and Chemical Composition of Peanut as Affected by Potassium and Gypsum Applications under Foliar Spraying with Boron

A field experiment was carried out at El-Khattara region (Sharkia Governorate, Egypt) during the 2009 season to study the effect of potassium (K) fertilization, gypsum addition rates, and foliar spraying with boron (B) and combinations of them on growth, yield, yield components, oil quality, and uptake of some macro- and micronutrients by peanut (Arachis hypogaea L. cv. Giza 6) grown on a sandy soil. Biological yield (pod + hay) as well as hay and seed yields were increased significantly as a result of K and gypsum application, but there was no significant increase under foliar spraying with B. The greatest values of 7788, 6585, and 954 kg fed^?1 for biological, hay, and seed yields corresponded to 20.8 kg K fed^?1 + 0.5 ton gypsum fed^?1 without foliar spraying with B. For hay, the greatest value of N uptake was obtained with 20.8 kg K fed^?1 + 1.0 ton gypsum fed^?1, whereas the greatest values for P and K uptake (70.1 and 131 kg fed^?1) were obtained when 20.8 kg K fed^?1 + 0.5 ton gypsum fed^?1 was applied under spraying with B. For seeds, the greatest value of K uptake was obtained when 20.8 kg K fed^?1 + 1.0 ton gypsum fed^?1 was applied, whereas for N and P uptake the greatest values (60.8 and 15.2 kg fed^?1) were obtained when 20.8 kg K fed^?1 + 0.5 ton gypsum fed^?1 were applied under spraying with B. The oil yield of peanut seeds using the Soxhelt extraction method was found to be in the range of 23.1 to 35.2%. The greatest B uptake in hay was obtained without spraying with B, whereas in seeds it was obtained under spraying with B. In both of them was obtained upon application of 20.8 kg K fed^?1 + 0.5 ton gypsum fed^?1. Apparent K recovery (AKR) and K-use efficiency (KUE) were markedly decreased with increasing K addition rates.     

新铁炮百合花芽分化及发育过程中氮磷钾含量变化的研究

在以往形态学研究的基础上,对新铁炮百合花芽分化及发育过程中叶片内氮、磷、钾含量的变化规律进行了研究。结果表明:在花芽分化及发育过程中,氮、磷、钾含量均有所下降且在花原基分化时期含量明显低于未分化期,外花被原基形成期氮、钾含量较高,三者的含量关系为钾氮磷;因此,新铁炮百合花芽分化及发育过程中,较低水平的氮、磷、钾有利于新铁炮百合的花芽分化,相对高水平的氮、钾有利于其花芽的发育,高水平的钾对新铁炮百合花芽分化及发育有一定的促进作用。     

Using Soil Potassium Adsorption and Yield Response Models to Determine Potassium Fertilizer Rates for Potato Crop on a Calcareous Soil in Pakistan

Ustochrept soil was collected from a major potato-growing area in Pakistan for a potassium (K) adsorption isotherm experiment. Adsorption data were fitted to Freundlich and Langmuir adsorption models. Results showed that the Freundlich model (R²?=?0.96**) fit the data better than did the Langmuir model. Fertilizer rates were calculated based on the Freundlich model and targeted solution K levels at 0, 3, 6, 9, 12, 15, 18, 21, 24, and 27 mg K L^?1. A field experiment was then conducted on the soil to assess the effect of various soil solution K levels (0–27 mg L^?1, with K fertilizer rates at 0, 24, 49, 75, 101, 128, 155, 182, 210, and 237 kg ha^?1), on tuber yield and quality along with 300 kg N and 250 kg P₂O₅ ha^?1 as basal doses. Yield response models (linear plus plateau, quadratic, square root, quadratic plus plateau, and exponential) were used to calculate the optimal fertilizer rate for potato crop. Linear plus plateau model fit the data with less bias than the other models. There was a significant effect of K use on the yield and quality of potatoes. Potassium fertilizer application at 130 kg K ha^?1, which is equivalent to a soil solution level of 12 mg K L^?1, maximized the tuber yield of potato. However, for the improvement in tuber dry matter, reducing sugars, protein contents, and starch contents, the soil solution K level required was as high as14.62 mg L^?1 (157 kg ha^?1). Even greater rate of K, 17.74 mg L^?1 (190 kg ha^?1), was needed to maximize vitamin C content in potato.     

Allelopathic effect of the root exudates of K21, a potent allelopathic rice

An inhibitory effect of the phenolic compounds released from the roots of K21, a newly bred potent allelopathic rice, was investigated in comparison to its male parent, Kouketsumochi, and its female parent, Dongjinbyeo. The inhibitory rates of the root exudates of K21 and both of its parents, collected at 5 day intervals, on the shoot growth of Echinochloa crus-galli var. praticola exhibited an increasing trend from 19–34 days after seeding (DAS). However, the root exudates of K21, at concentrations of 0.5, 1.0, and 2.0%, showed a greater inhibitory effect than those of its female parent on the growth of E. crus-galli var. praticola at the earlier collection dates. Nine phenolic compounds were identified; the total amount of phenolic compounds in the exudates increased from 19–34 DAS in both K21 and its male parent, but not much in the female parent. The subsequent increase in the amount of total phenolic compounds in the root exudates of the later investigation dates and the trend of increasing inhibitory rates on the shoot growth of E. crus-galli var. praticola at higher exudate concentrations imply that the increased amount of phenolic acids in the root exudates of K21 secreted on the subsequent dates could be related to its greater allelopathic effects.     

西部农业土壤固定态铵及影响因素的研究

以西部地区24种土壤为对象,测定了土壤中的固定态铵、固铵能力、全钾、缓效钾、无效钾、交换钾、交换铵、阳离子交换量、全氮、有机质和pH等,研究了它们与固定态铵之间的关系。结果表明,土壤固定态铵含量平均179mg/kg,占全氮16.6％;土壤固铵能力平均27.8％;土壤固定态铵与固铵能力显著正相关,与土壤全钾、缓效钾、无效钾极显著正相关,与阳离子交换量显著正相关,与土壤全氮、全磷、有机质、pH、交换钾、交换铵相关不显著。     

Potassium forms in calcareous soils as affected by clay minerals and soil development in Kohgiluyeh and Boyer-Ahmad Province,Southwest Iran

Potassium(K) is known as one of the essential nutrients for the growth of plant species. The relationship between K and clay minerals can be used to understand the K cycling, and assess the plant uptake and potential of soil K fertility. This study was conducted to analyze the K forms(soluble, exchangeable, non-exchangeable and structural) and the relationship of K forms with clay minerals of calcareous soils in Kohgiluyeh and Boyer-Ahmad Province, Southwest Iran. The climate is hotter and drier in the west and south of the province than in the east and north of the province. A total of 54 pedons were dug in the study area and 32 representative pedons were selected. The studied pedons were mostly located on calcareous deposits. The soils in the study area can be classified into 5 orders including Entisols, Inceptisols, Mollisols, Alfisols and Vertisols. The main soil clay minerals in the west and south of the study area were illite, chlorite and palygorskite, whereas they were smectite, vermiculite and illite in the north and east of the province. Due to large amount of smectite and high content of organic carbon in soil surface, the exchangeable K in surface soils was higher than that in subsurface soils. It seems that organic matter plays a more important role than smectite mineral in retaining exchangeable K in the studied soils. Non-exchangeable K exhibited close relationships with clay content, illite, vermiculite and smectite. Although the amount of illite was the same in almost all pedons, amounts of structural and non-exchangeable K were higher in humid regions than in arid and semi-arid regions. This difference may be related to the poor reservoir of K~+ minerals like palygorskite and chlorite together with illite in arid and semi-arid regions. In humid areas, illite was accompanied by vermiculite and smectite as the K~+ reservoir. Moreover, the mean cumulative non-exchangeable K released by CaCl_2 was higher than that released by oxalic acid, which may be due to the high buffering capacity resulting from high carbonates in soils.