浅谈财务预测的概念和作用

本文阐述了财务预测的概念和作用,针对财务预测的局限性,提出根据预测结果对经营活动进行调整,使其更为准确,使企业提高经济效率。     

民事责任原则重构——辛卜偿性责任价值质疑

补偿性责任几乎是我国目前确定民事责任的唯一原则，笔者对其操作价值，补偿与救济价值，惩罚、教育、预防和遏制价值，以及平等、公平、公正、正义价值进行剖析，建议重构民事责任原则，即确立补偿性责任为一般原则，惩罚性责任为辅助原则，限制性责任为例外原则，一元钱赔偿为适当适用的原则。     

No life-history cost of tebufenozide resistance in the smaller tea tortrix moth

BACKGROUND

Tebufenozide is widely used to control populations of the smaller tea tortrix, Adoxophyes honmai. However, A. honmai has evolved resistance such that straightforward pesticide application is an untenable long-term approach for population control. Evaluating the fitness cost of resistance is key to devising a management strategy that slows the evolution of resistance.

RESULTS

We used three approaches to assess the life-history cost of tebufenozide resistance with two strains of A. honmai: a tebufenozide-resistant strain recently collected from the field in Japan and a susceptible strain that has been maintained in the laboratory for decades. First, we found that the resistant strain with standing genetic variation did not decline in resistance in the absence of insecticide over four generations. Second, we found that genetic lines that spanned a range of resistance profiles did not show a negative correlation between their LD₅₀, the dosage at which 50 % of individuals died, and life-history traits that are correlates of fitness. Third, we found that the resistant strain did not manifest life-history costs under food limitation. Our crossing experiments indicate that the allele at an ecdysone receptor locus known to confer resistance explained much of the variance in resistance profiles across genetic lines.

CONCLUSION

Our results indicate that the point mutation in the ecdysone receptor, which is widespread in tea plantations in Japan, does not carry a fitness cost in the tested laboratory conditions. The absence of a cost of resistance and the mode of inheritance have implications for which strategies may be effective in future resistance management efforts. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

AM真菌和磷对小马安羊蹄甲幼苗生长的影响

丛枝菌根(arbuscular mycorrhizal,AM)真菌在退化生态系统恢复与重建实践中具有重要作用。采用盆栽模拟方法,重点分析不同土壤磷条件下小马鞍羊蹄甲(Bauhinia faberi)幼苗接种AM真菌后,幼苗的形态、生物量积累、菌根侵染率和菌根效应(mycorrhizal growth response, MGR)在一个生长季内的动态变化。结果表明,Glomus mosseae和 Glomus coronatum能较好地侵染幼苗,两种AM真菌显著地增加幼苗根系、叶片数和生物量;接种AM真菌显著影响幼苗的生物量分配,而土壤磷对幼苗的生物量分配影响不明显,AM真菌和土壤磷对幼苗生长的交互作用显著;G. mosseae是小马鞍羊蹄甲的优势AM菌,其接种的幼苗根长、叶片数、生物量、侵染率和菌根效应都显著高于G. coronatum处理的幼苗;菌根效应显著,接种AM真菌能有缓解土壤磷素缺乏的限制作用,且随着苗龄增大促生作用表现更为明显。不同AM菌种对小马鞍羊蹄甲幼苗生长的促生作用表现出的差异,提示在多元资源限制的干旱贫瘠环境中进行生物修复须为目标恢复物种筛选出高效的优势AM真菌。     

A simple method to estimate harvest index in grain crops

Several methods have been proposed to simulate yield in crop simulation models. In this work, we present a simple method to estimate harvest index (HI) of grain crops based on fractional post-anthesis phase growth (f_G = fraction of biomass accumulation that occurred in the post-anthesis phase). We propose that HI increases in a linear or curvilinear fashion in response to f_G. The linear model has two parameters, the intercept (HI_o) and the slope (s). The curvilinear model was assumed to be monotonic: HI = HI_x − (HI_x − HI_o) · exp(−k·f_G); where HI_x is the asymptote, HI_o is the intercept and k is a constant modulating the rate of HI increase. The models were tested for barley (Pullman, WA and Uruguay), wheat (Pullman, WA) and sorghum (Australia). A positive relationship between HI and f_G was in general evident. For barley, the linear model appropriately represented the response of HI to f_G, with both HI_o and s in the vicinity of 0.3. For wheat HI_o and s were 0.34 and 0.21, respectively, but the curvilinear model yielded a slightly better fitting than the linear model. For sorghum, both linear and linear-plateau models fitted data reasonably well. It is shown that the models work well in crops source-limited or source-sink co-limited during grain filling, but in sink-limited conditions the magnitude of the limitation needs to be characterized to compute HI. A major advantage of this method is that the parameters of the linear or curvilinear model are readily calibrated from yield data and biomass measurements at anthesis and harvest.     

Comparison of factors limiting bacterial growth in different soils

Lack of carbon has been assumed to be the most common limiting factor for bacterial growth in soil, although there are reports of limitation by other nutrients, e.g. nitrogen and phosphorus. We have studied which nutrient(s) limited instantaneous growth rates of bacteria in 28 Swedish soils using the thymidine or leucine incorporation technique to measure increased growth rate after adding different combinations of organic carbon (glucose), nitrogen and phosphorus. The soils ranged in pH between 3.1 and 8.9, in organic matter content between 1% and 91% and in soil C/N ratio between 10 and 28. We also tested the effect of adding different amounts of carbon on the bacterial change in growth rate for two soils with different organic matter content. We found that bacterial growth in most of the 28 soils was limited by a lack of carbon, indicated by an increased bacterial growth rate 48 h after adding glucose. In some soils, adding carbon together with nitrogen increased the bacterial growth rates even further. In three soils no effects were seen upon adding nutrients separately, but adding carbon and nitrogen together increased bacterial growth rates. Nitrogen addition tended to decrease bacterial growth rates, while phosphorus addition had little effect in most soils. No correlations were found between the soil C/N ratio, ammonium or nitrate content in soil and bacterial growth limitation, indicating that even soils with a C/N ratio of 28 could be carbon limited. Although the interpretation of the effects of a single limiting nutrient was in most cases straightforward, an interaction between the amount of carbon added and the organic matter content of the soil confounded the interpretation of the extent of a second limiting nutrient.     

土壤生物炭的生产：三种窑模型的比较研究

Biochar has potentials for soil fertility improvement, climate change mitigation and environmental reclamation, and charred biomass can be deliberately incorporated into soil for long-term carbon stabilization and soil amendment. Many different methods have been used for biochar production ranging from laboratory to industrial scales. However, in countryside of developing countries,biomass is generally used for cooking but not charred. Biochar production techniques at farmer scale have remained poorly developed.We developed and tested biochar production kilns for farmers with a dimension of 50.8 cm × 38.1 cm(height × diameter), using three different setups for optimizing oxygen(O2) limitation and syngas circulation: airtight with no syngas circulation(Model I),semi-airtight with external syngas circulation(Model II) and semi-airtight with internal syngas circulation(Model III). A comparative assessment of these biochar production kiln models was made considering biochar pyrolysis time, fuel to biomass ratio, biochar to feedstock ratio and thermogravimetric index(TGI). Among the models, the best quality biochar(TGI = 0.15) was obtained from Model I kiln taking the longest time for pyrolysis(12.5 h) and the highest amount of fuel wood(1.22 kg kg-1biomass). Model III kiln produced comparatively good quality biochar(TGI = 0.11), but with less fuel wood requirement(0.33 kg kg-1biomass) and shorter pyrolysis time(8.5 h). We also tested Model III kiln in a three times larger size under two situations(steel kiln and pit kiln). The biochar to feedstock ratio(0.38) and quality(TGI = 0.14) increased slightly for the larger kilns. Quality of biochar was found to be mainly related to pyrolysis time. The costs for the biochar stove and pit kiln were US$ 65–77, while it was US$ 154 for the large size steel kiln. Model III kiln can potentially be used for both cooking and biochar production at farmer scale.     

Land-use history and plant performance in populations of Trillium grandiflorum

Many forest herbs show reduced frequency in forests growing on former agricultural land (secondary forests) relative to forests that were never cleared for agriculture (primary forests). To explain this pattern, studies of secondary forest colonization by forest herbs have stressed the role of limited seed dispersal, though environmental conditions may also limit colonization. Here I demonstrate that adult plant performance of Trillium grandiflorum is significantly reduced in secondary vs. primary forests in central New York State, USA. Comparing primary and secondary sites both with relatively high soil pH, T. grandiflorum populations were more dense, and individual plants were larger and more likely to be flowering in primary than secondary forests. Using counts of annual leaf scars on the rhizome, I demonstrate that this result is not due to secondary populations being younger than primary populations. Age-specific leaf area was significantly greater in primary than secondary stands at high soil pH, and the data suggest slightly reduced seed set in secondary stands as well. These results point to a more important role for environmental conditions in limiting forest-herb colonization of secondary forests than has been previously appreciated. Restoration and conservation of forest herbs in post-agricultural forests will require more than simply overcoming dispersal limitation.     

干热河谷土壤酶活性和车轴草生长对氮磷添加的响应

为了探讨干热河谷地区不同土地利用类型下土壤酶活性和植物生长对氮磷添加的响应以及二者之间的联系,采集了元谋干热河谷6种不同土地利用类型土壤,包括灌丛、草地、森林、新开垦农田(新农)、常年耕作农田(常农)、侵蚀裸地(裸地),并利用盆栽探索了土壤酶活性和车轴草(Trifolium repens L.)生长对氮(N)、磷(P)、氮磷(N+P)处理的响应特征。结果表明:(1)植物生物量受土地利用类型和处理双重因素影响,两者的交互作用对植物生物量具有显著作用。(2)除农田土壤(新农和常农)外,其他土地利用类型的土壤上植物生长受到养分添加的显著影响,其中添加P处理的生物量显著高于对照; 而N+P处理又显著高于单一的P添加; 而新农和常农不同养分处理间植物生物量差异不显著。(3)土壤酶活性受土地利用类型显著影响,但是不同养分添加处理之间土壤酶活性差异不显著; 土壤酶活性与植物生物量无显著相关性。综上,干热河谷土壤中植物生长的限制养分主要为磷,然而土壤酶活性则不受氮磷养分的限制,其活性主要与土地利用类型有关。     

Control of cotton pests and diseases by intercropping: A review

Cotton (Gossypium hirsutum L.) is a globally important crop that is often damaged by pests and diseases. Current cotton pests and diseases management is dependent on chemical pesticides. Although chemical pesticides are usually effective, long-term application of these pesticides often leads to increased insecticide resistance in the pests, fewer natural enemies, reduced natural control, and a degraded environment. Because of increased environmental awareness and the need for sustainable cotton production, the control of cotton pests and diseases using biological means like intercropping is increasingly receiving attention. Intercropping of cotton with other crops can often boost the total yield and output of the intercropping system and provide significant economic benefits without sacrificing cotton quality. Intercropping also increases the number of natural enemies, and reduces the occurrence of cotton pests and diseases by altering the ecological structure and environmental conditions in the fields. Cotton-based intercropping is an effective strategy to reduce the competition between cotton and grain or other economic crops for arable land. It is also an important way to increase the populations of natural enemies in cotton fields for the management of pests and diseases. However, inappropriate intercropping can also increase labor requirements and even result in inadequate control of pests and diseases. This review focuses on the performance and the mechanisms of intercropping for reducing cotton pests and disease as well as on the effective management of intercropping systems. The risks and limitations, as well as the study approaches needed and the prospects of intercropping for the control of cotton pests and diseases, are also discussed. This information is intended to aid researchers and growers in designing economically viable and ecologically friendly pest and disease management strategies that will reduce the use of chemicals and the cost of cotton production.