Microbial and enzyme activity in soils amended with a natural source of easily available carbon

The addition of sugar beet to soils as a source of C led to an increase in the availability of easily utilizable C (glucose), which in turn markedly increased numbers of soil bacteria and of the yeast Williopsis californica. Nitrification, P solubilization, urea hydrolysis (and the subsequent nitrification of liberated NH _inf4 ^sup+ ) were stimulated by this amendment. The stimulation of nitrification may have been a result of increased heterotrophic nitrification. In contrast, the concentration of sulphate in S^o-amended soils declined following amendment, presumably as the result of enhanced S immobilization. Activity of the enzymes amylase, aryl sulphatase, invertase, phosphatase, dehydrogenase, and urease were all stimulated by the sugar beet amendment. These results suggest that sugar beet amendment could be used to increase the rate of release of plant-available ions from fertilizers such as insoluble phosphates. Problems may arise, however, from a subsequent increase in nitrification and reduced sulphate availability.     

甜菜渣提取果胶后剩余残渣的利用

对甜菜渣提取果胶后剩余残渣的利用，提出了两条有效途径：一是采用物理方法制取食物纤维。残渣经水反复洗涤，用无水乙醇脱水后，在不同温度下真空干燥。结果表明在较低温度下可得到白色无毒的食物纤维。二是将残渣氧化制备草酸。通过对不同催化剂催化效果的研究，结果表明用Ｖ２Ｏ５—Ｆｅ２（ＳＯ４）３—ＡｇＮＯ３作催化剂，草酸的产率较高且重现性好。     

Soil dynamics of the origination of soil tare during sugar beet lifting

High soil tare of sugar beet on wet clay soil after uprooting with share lifters is usually attributed to the fact that the soil becomes sticky due to mechanical impact during uprooting. Results of field experiments have shown good potential for obtaining low soil tare of sugar beet on wet clay soil by beet extraction with a high average vertical acceleration and a spiral extraction path with a small pitch. The objective of this research was to provide models for soil–beet–lifter systems used in these experiments, and to simulate some of the observed effects of the uprooting method on soil tare and soil adherence. As the rootlet system plays an important role in the origination of soil tare, the rootlet system was also modelled. A constitutive soil model, assuming elastic–perfectly-plastic soil behaviour, was used as a basis for modelling soil–beet–lifter system variants, including beet with and without rootlets, uprooting by extraction, rotation and extrusion, and uprooting with low and high vertical acceleration. The origination of soil tare is presented on the basis of the calculated zone of initial soil failure during extraction. Expected soil adherence is discussed in relation to the stress state of the soil. The simulated initial soil failure and stress state of the soil agreed well with experimental results on soil tare and soil adherence.     

河套地区甜菜含糖与相关因素的调查

调查结果表明,甜菜收获前割擗叶子、过量施氮肥和低密度种植是影响河套地区甜菜糖分的主要因素,可降低含糖3.0～4.0锤度;其次是提前收获,可降低含糖约2.0锤度。该区有利于提高甜菜含糖的适宜保苗密度为6.7～7.5万株/hm2,种肥适宜用量为:氮30～75kg/hm2,磷60～120kg/hm2,钾22.5kg/hm2;追肥适宜用量为:氮120～180kg/hm2,磷45kg/hm2,钾60kg/hm2。同时要注意选用优良品种,它是影响甜菜含糖的内在因素。     

甜菜根际磷酸酶分泌特性的研究

甜莱根际磷酸酶的分泌特性是其根际土壤中有机磷有效性的决定性因子。采用液体培养和改进的Kuchenbuch微型盒土培法。对甜莱根际磷酸酶的分泌情况进行了较详细的研究。结果表明：(1)甜莱对有机磷的吸收是以有机磷的分解转化为前提，不同基因型的甜莱根际产生磷酶的种类、分布范围及分泌总量存在明显差异。并表现在对有机磷胁迫的抗耐能力方面的差别。某些基因型对有机磷表现出极强的分解、吸收和适应能力；(2)甜莱根系可分泌出多种磷酸酶。其中绝大多数品种以酸性磷酸酶为主。其次是中性磷酸酶．而碱性磷酸酶几乎没有；(3)甜莱各品种(系)根际磷酸酶的分布均表现出从根表向根际以外逐渐由高到低的特点。当达到一定点趋于一个恒定的值，符合方程y=yo ae^(-bx)的分布规律。     

Effect of Two Magnesium Fertilizers on Leaf Magnesium Concentration,Yield, and Quality of Potato and Sugar Beet

Twelve field experiments were conducted to study the impacts of calcined magnesite and Kieserite fertilizers on yield, quality and leaf concentrations of magnesium (Mg) in potatoes and sugar beet. The rate of Mg applied was 60 kg Mg ha^?1, and the experiments were realized in six locations for both crop species. There were clear increases in leaf Mg concentration and yield of both crops resulting from application of Mg fertilizers. Mean increase in leaf Mg concentration and crop yield for both species were more pronounced with Kieserite than with calcined magnesite. Sugar concentrations of sugar beet and dry matter yield of potatoes were, however, influenced only slightly by the Mg fertilizers. It seems that superiority of Kieserite to calcined magnesite is related to higher Mg solubility of Kieserite. Use of Mg fertilizers with higher solubility helps to avoid the risk of Mg deficiency and subsequent losses in yield and economic returns.     

Interactive effect between Cu‐adapted arbuscular mycorrhizal fungi and biotreated agrowaste residue to improve the nutritional status of Oenothera picensis growing in Cu‐polluted soils

The interactive effect of sugar beet (SB) agrowaste and arbuscular mycorrhizal (AM) fungi inoculation in response to increasing Cu levels was evaluated in the metallophyte Oenothera picensis. Plants were grown in a Cu‐added soil (0, 100, or 500 mg Cu kg^?1), in presence or absence of SB, and inoculated with: (1) indigenous Cu adapted mycorrhiza (IM) isolated from Cu‐polluted soils; (2) Claroideoglomus claroideum (CC); or (3) maintained uninoculated (control). Sugar beet application produced an increase in shoot biomass of 2 to 7 times, improving plant nutritional status and allowing their survival at the highest Cu concentrations. Moreover, AM fungi utilization had a positive effect promoting the plant establishment; nevertheless, Cu plant concentration as well as the mycorrhizal development in terms of AM colonization, AM spore density, and glomalin production were strictly dependent of the AM fungi strains used. Remarkable differences between AM fungi strains were observed at the highest soil Cu level where only plants colonized by IM were able to survive and grow when no SB residue was added. An interactive effect between AM fungi and SB produced a higher plant growth than plants without the amendment application, improving the plant establishment and allowing their survival at highest copper concentrations, suggesting that this combination could be used as a biotechnological tool for the phytoremediation of Cu‐polluted soils.     

Modelling the variability of UK sugar beet yields under climate change and husbandry adaptations

In the future, UK summers are likely to be warmer and drier. Modelling differential water redistribution and uptake, we assessed the impact of future drier climates on sugar beet yields. Weather was generated for 1961–1990 (BASE) and predictions based on low‐ and high‐emission scenarios (LO, HI) described in the most recent global climate simulations by the Hadley Centre, UK. Distributions and variability of relative soil moisture deficit (rSMD) and yield gap (drought‐related yield loss, YG_dr = 1?actual yield/potential yield), and sugar yield were calculated for different time‐lines using regional weather, soil texture and management inputs. The rSMD is estimated to exceed the senescence threshold with a probability of 75% (2050sLO) to 95% (2080sHI) compared with 65% (BASE). The potential yield loss, YG_dr, is likely to increase from 17% (BASE) to 22% (2050sLO) to 35% (2080sHI). However, increasing potential growth rates (CO₂ × temperature) cause average sugar yields to rise by between 1.4 and 2 t ha^?1 (2050sLO and 2050sHI respectively). Yield variation (CV%) may increase from 15–18% (BASE) to 18–23% (2050s) and 19–25% (2080s). Differences are small between regions but large within regions because of soil variability. In future, sugar yields on sands (8 t ha^?1) are likely to increase by little (0.5–1.5 t ha^?1), but on loams yields are likely to increase from 11 to 13 t ha^?1 (2050sHI) and 15 t ha^?1 (2080sHI). Earlier sowing and later harvest are potential tools to compensate for drought‐related losses on sandy soils.     

应用电导率评价蔬菜抗病性的最佳时期

以菜豆、芫荽、根甜菜和甘蓝的抗病和感病品种为试材,分别接种了根腐病(Rhizoctonia solani),叶斑病(Ramularia coriandri),立枯病(Aphanomyces cochlioides 等)和灰霉病(Botrytis cinerea)病原菌,并测定病原菌侵染后的电导率。结果表明:菜豆、芫荽和甘蓝在接种后第3天,根甜菜在接种后第4天,感病品种的电导率值比抗病品种分别高28％、25％、179％和12％,因此,这一时间可以作为鉴定以上4种蔬菜抗病性的最佳时期。