氨基酸螯合多元微肥拌种对玉米苗期生长的影响

玉米采用氨基酸螯合多元微肥拌种可显著地促进根系和地上部的生长，拌种后可使玉米地上部和根系的干物重分别提高22.5%和16.8%，根系活力提高72%，叶片光合强度提高56%，氨基酸螯合多元微肥对玉米的适宜拌种浓度为100倍。     

施氮对油菜硫、硼、钼和硒营养的影响

研究了不同氮水平与杂交油菜收获期植株各器官硫、硼、钼和硒等元素含量和积累的关系。植株各器官（种子除外）的硫以及种子和主茎中的硼含量随施氮量的增加呈先升后降的趋势，但植株各器官的钼、硒和种子的硫以及其余各器官的硼含量随施氮量的增加有所下降。种子和主茎的硫以及果壳的钼、硼和硒的含量及积累量较高。     

Spatial distribution and physiology of biological soil crusts from semi-arid central Spain are related to soil chemistry and shrub cover

Despite the critical role of biological soil crusts (BSCs) in arid and semi-arid ecosystem function, few studies are found concerning the most important environmental variables affecting their distribution and physiology. This study seeks to determine soil and microenvironmental factors affecting the spatial distribution and pigment production of BSC-forming lichens and mosses in open patches of a semi-arid Mediterranean kermes oak thicket. We measured late-successional BSC cover, shrub cover, distance to nearest kermes oak (to test for effects of kermes oak thicket microenvironment on BSC), and pigment concentration of one lichen (Cladonia foliacea) and one moss (Pleurochaete squarrosa) species in the Nature Reserve El Regajal-Mar de Ontígola (Central Spain). At the macroscale (>0.5 m), results showed that BSC distribution and pigments were tightly coupled to a suite of soil properties, in particular soil pH, Fe, and Ca. Specifically, soil pH had a positive relationship with the cover of five individual BSC-forming lichen species and was negatively related to pigment production in C. foliacea. When pH was excluded from the analysis, Ca appeared as the main soil variable and was correlated with total BSC cover and total lichen cover. The micronutrient Fe had a significant positive relationship with the concentration of eight pigments in P. squarrosa and was also coupled with the cover of two BSC-forming lichens. Manganese, previously proposed as a key limiting micronutrient for BSCs, affected lichen diversity in a negative way. At the microscale (∼0.5 m), kermes oak microenvironment, shrub cover, and moss cover were determinants of BSC distribution, and total lichen and total BSC cover were overrepresented on N and E-facing shrub microsites. Our findings suggest that soil chemical variability and microsite diversity created by neighbouring vegetation affect BSC distribution in complex and essential ways and that studies aiming to explore BSC-environment relationships should be conducted at various spatial scales. Studies based on species- or group-specific responses are, thus, inadequate to unveil the main factors determining the distribution of the diverse organisms that constitute BSCs and/or to propose potential tools aiming to restore BSC in arid and semiarid ecosystems.     

印度酸性耕作土中总锰、铁以及可提取态锰、铁的水平、分布及其与土壤性质的关系研究

A total of 400 surface soil(0–15 cm) samples were collected from cultivated soils representing four soil series,namely,Hariharapur,Debatoli,Rajpora and Neeleswaram in Orissa,Jharkhand,Himachal Pradesh and Kerala states of India,respectively,and were analyzed to measure the contents of total and extractable Mn and Fe,to establish the relationship among total and extractable Mn and Fe and soil properties,and to characterize the spatial distribution pattern of Mn and Fe in some cultivated acid soils of India. The contents of total as well as extractable Mn and Fe varied widely with extractants and soil series. However,the amounts of Mn or Fe extracted by diethylene triamine penta-acetic acid(DTPA),Mehlich 1,Mehlich 3,0.1 mol L-1 HCl and ammonium bicarbonate DTPA(ABDTPA) were significantly correlated with each other(P 0.01). Based on the DTPA-extractable contents and the critical limits(2 mg Mn kg-1soil and 4.5 mg Fe kg-1 soil) published in the literature,Mn and Fe deficiencies were observed in 7%–23% and 1%–3% of the soil samples,respectively. The content of soil organic carbon(SOC) had greater influence on total and DTPA-extractable Fe than did soil pH. Geostatistical analysis revealed that total and DTPA-extractable Mn and Fe contents in the acid soils were influenced by soil pH,SOC content,and exchangeable cations like potassium,calcium and magnesium. Spatial distribution maps of total and DTPA-extractable Mn and Fe in soil indicated different distribution patterns.     

Evaluation of certain Ni soil tests for an initial estimation of Ni sufficiency critical levels

Although Ni is officially recognized as an essential micronutrient for all higher plants, the majority of the published research on soil availability of Ni focuses on its hazardous role as a heavy metal. The objective of the study was to evaluate certain Ni soil tests in uncontaminated soils for an initial estimation of its sufficiency critical levels. Nickel was extracted from 30 cultivated soils employing the following extraction methods: DTPA, AB‐DTPA, AAAc‐EDTA, Mehlich‐3, 0.1 M HCl, and 0.1 M HNO₃. Ryegrass (Lolium perenne L.) was grown in pots containing the soils, harvested five times, certain plant parameters were determined, and the Cate–Nelson procedures were used for Ni critical levels determination. Among the six methods, HCl was the least reliable extractant for the evaluation of soil available Ni, whereas the most significant (p ≤ 5%) relationships between Ni concentration or Ni uptake by ryegrass and Ni soil tests were consistently obtained for AAAc‐EDTA or Mehlich‐3 extractable Ni. In many cases, > 80% of the variability of Ni concentration or uptake by ryegrass was explained by these two soil tests without the inclusion of other soil properties that affect Ni bioavailability. Sufficiency critical levels of Ni in soil were ≈ 2 mg kg^–1 for both methods. Consequently, as an initial approach, concentrations of AAAc‐EDTA or Mehlich‐3 extractable Ni < 2 mg kg^–1 are probably a good guide to indicate soils that will respond to Ni fertilization.     

夏高粱的锌锰营养及施肥效应的研究

夏高粱对锌、锰的吸收情况为:苗期较慢,拔节至齐穗阶段达高峰,此时亦是干物质增加最快的时期,齐穗以后吸收逐渐减慢。田间试验结果表明,施用锌、锰肥可使夏高粱籽粒产量比对照分别增加8.3%和6.0%。施用锌、锰肥能促进植株对锌、锰的吸收和提高植株体内的锌、锰含量,增加每穗粒数和千粒重。盆栽试验显示,在不同土壤上,夏高粱对锌、锰肥的反应差异较大,这主要取决于土壤中锌、锰的有效性。     

Rice residue incorporation and nitrogen application: effects on yield and micronutrient transformations under rice–wheat cropping system

Abstract

Despite being a major domain of global food supply, rice–wheat (RW) cropping system is questioned for its contribution to biomass burning in Indo-Gangetic Plains (IGP). Enhancing the yield and soil quality properties in this system is therefore necessary to reduce environmental degradation and maintain agricultural productivity. A field experiment evaluated the effects of soil management practices such as rice residue (RS) incorporation, and nitrogen (N) application on crop yield and micronutrients transformations in a RW cropping system of north-western India. The results revealed that N application (120?kg N ha^?1) and RS incorporation (7.5 t ha^?1) significantly increased micronutrients cations and crop yield compared with no-residue (RS₀). Irrespective of N application, crop grain yield under RS incorporation (Rs_7.5 t ha^?1) was significantly higher than RS₀ incorporation. Significant increase in all the micronutrient transformations was recorded in N₁₂₀/Rs_7.5 t ha^?1 compared with RS₀. Among different fractions, crystalline Fe bound in Zn, Mn, and Cu and amorphous Fe oxide in Fe fractions were the dominant fractions under N application (N₁₂₀) and RS incorporation (RS_7.5) treatment. Our study showed that application of N₁₂₀ followed by RS_7.5 can be more sustainable practice under RW cropping system for improvement in micronutrients availability and crop yield. This practice also provides an opportunity to incorporation of crop residues as an alternative to burning, which causes severe air pollution in the RW cropping system in the IGP.     

不同光周期下外源锌对水培生菜生长和品质的影响

以意大利耐抽薹生菜为试材,采用水培法,设置不同光周期(12 h/12 h、16 h/8 h、20 h/4 h)和外源锌浓度(0、0.5、1 mg/L ZnSO₄·7H₂O),研究不同光周期下外源锌对水培生菜生长和品质特性的调控效应。试验结果表明,16 h/8 h光周期处理有利于生菜地上部的生长以及维生素C、类黄酮和总酚含量的增加,而20 h/4 h光周期处理有利于生菜地下部的生长及可溶性蛋白质、可溶性糖和还原糖含量的增加,但20 h/4 h光周期处理会对生菜的生长产生抑制作用,从而影响干物质的积累。从光周期与锌互作效果看,光周期对生菜生长和品质的影响起主导作用,外源锌起调节作用。综上所述,16 h/8 h光周期下根施0.5 mg/L Zn对促进生菜生长、提升品质效果最佳。     

配合施肥对云南冬季亚麻生长及土壤肥力的影响

如何保证亚麻正常生长和亚麻地土壤肥力稳定及养分平衡,是亚麻新产区非常关注的问题。以氮、磷、钾和几种主要微量元素进行2因素随机区组试验的结果显示,不同肥料处理组合对亚麻农艺性状的影响各不相同,对有效株数影响最大,单茎重、株高与工艺长度居其次,而茎粗所受影响最小,且大量元素对亚麻生长的影响要比微量元素更大。依据亚麻综合性状表现,配合施肥以A3B1、A2B0、A3B2、A2B2处理组合比较理想,亚麻原茎产量达到13.3t/hm2以上。在配合适量施肥前提下,亚麻地土壤肥力基本保持稳定。     

Nutritional composition and micronutrient status of home made and commercial weaning foods consumed in Tanzania

About 50% of young children in Tanzania suffer from protein-energyundernutrition (PEU) while more than 45% of children under the age offive suffer from various micronutrient deficiency disorders. The immediatecause of these conditions is inadequate intake and poor utilization ofnutrients, which begins in the weaning period and amplifies in thesubsequent years. This study was conducted to assess the potential of somehome made and commercial weaning foods commonly consumed in Tanzania tosupply adequate amounts of both macro- and micronutrients as recommendedin the Tanzania and FAO/WHO Codex Alimentarius Standards forcereal/milk-based weaning foods. Six types of home made weaning foods,maize, cassava, millet, sorghum and millet-sardine-peanut composite gruelsand plantain pap, and four types of commercial weaning foods, Cerelac-1,Cerelac-2, Lactogen-1 and Lactogen-2, popularly consumed in Tanzania, werechemically assayed for proximate composition, energy and mineral density.Results of the study indicated that, both the home made and commercialweaning foods were good sources of macro- and micronutrients. Whencompared with the Codex Alimentarius and Tanzania Bureau of Standardsspecifications for weaning foods, both home made and commercial weaningfoods had some shortcomings in terms of nutrient composition and energybalance. Many of the foods were low in fat, Fe, Ca, Zn and P but high incrude fiber, carbohydrate and magnesium. Ca, Fe and Zn were the mostcommon deficient macro/micronutrients in the home made weaning foods. Inspite of these shortcomings, most of the home made and commercial weaningfoods were nutritionally sound since they could provide reasonablepercentages of the recommended daily allowances for macro/micronutrientsand energy. It is suggested that, more efforts must be directed towardsincreasing the concentration of Ca, Fe and Zn in the home made weaningfoods through supplementation of the starchy staples with mineral richfoods. Meanwhile, the parents, caretakers and health workers should beeducated on the selection and preparation of nutritious, balanced weaningfoods and good weaning practices.