Temperate agroforestry research: considering multifunctional woody polycultures and the design of long-term field trials

The many benefits of agroforestry are well-documented, from ecological functions such as biodiversity conservation and water quality improvement, to cultural functions including aesthetic value. In North American agroforestry, however, little emphasis has been placed on production capacity of the woody plants themselves, taking into account their ability to transform portions of the landscape from annual monoculture systems to diversified perennial systems capable of producing fruits, nuts, and timber products. In this paper, we introduce the concept of multifunctional woody polycultures (MWPs) and consider the design of long-term experimental trials for supporting research on agroforestry emphasizing tree crops. Critical aspects of long-term agroforestry experiments are summarized, and two existing well-documented research sites are presented as case studies. A new long-term agroforestry trial at the University of Illinois, “Agroforestry for Food,” is introduced as an experiment designed to test the performance of increasingly complex woody plant combinations in an alley cropping system with productive tree crops. This trial intends to address important themes of food security, climate change, multifunctionality, and applied solutions. The challenges of establishing, maintaining, and funding long-term agroforestry research trials are discussed.     

人工诱导池养3+龄鲥鱼性腺发育的初步试验与探讨

通过模似鲥鱼性腺发育的自然生态条件和埋植 LHRH-A 和 Testosterone 缓释放颗粒激素,诱导池养3~+龄鲥鱼性腺发育季至第1期,成熟系数达0.9%。试验摸索出麻醉操作鲥鱼不死的有效方法。对今后鲥鱼全人工繁殖的前景及有关问题进行了探讨.     

水稻持久抗瘟性生化鉴定的研究

对２个持久抗瘟性和２个感病水稻品种苗期接种稻瘟菌，分析接种前后叶片内的生化指标，结果表明：接种后感病品种过氧化物酶活性持续增加，接种９６ｈ后酶活性急剧上升，而持抗品种过氧化物酶活性增幅较少．接种前后持抗和感病水稻品种叶片蛋白质含量变化均不明显，前者蛋白质含量显著高于后者．接种后０～６ｄ内持抗品种叶片可溶性糖含量均低于感病品种，而持抗品种游离氨基酸含量高于感病品种．初步认为：接种后叶片的过氧化物酶活性可作为鉴别水稻品种抗瘟性的依据     

The carboxyterminal processing protease of D1 protein: Herbicidal activity of novel inhibitors of the recombinant and native spinach enzymes

The carboxyterminal processing protease of D1 protein (CtpA) is predicted to be an excellent target for the discovery of a general broad-spectrum herbicide. Directed and random screening of compounds against recombinant spinach CtpA (rCtpA) has led to the discovery of five different chemical classes of inhibitors. Lead compounds from each inhibitor class were investigated for their in vitro effects on the activities of both recombinant and native spinach CtpA. All of the lead compounds have K_i values of less than 50 μM when tested against rCtpA, and all except one showed competitive inhibition. Results from partially purified native CtpA from spinach were similar to those from the recombinant form of the enzyme, thus validating the use of rCtpA in the inhibitor screen. Compounds from three of the classes of CtpA inhibitors show in vivo herbicidal activity against Arabidopsis thaliana when applied either by addition to growth media or by spraying the leaves. Transgenic Arabidopsis plants which over-express CtpA showed greater resistance to the compounds than wild-type plants providing evidence that these inhibitors are directly acting against CtpA.     

Use of artificial landscapes to isolate controls on burn probability

Techniques for modeling burn probability (BP) combine the stochastic components of fire regimes (ignitions and weather) with sophisticated fire growth algorithms to produce high-resolution spatial estimates of the relative likelihood of burning. Despite the numerous investigations of fire patterns from either observed or simulated sources, the specific influence of environmental factors on BP patterns is not well understood. This study examined the relative effects of ignitions, fuels, and weather on mean BP and spatial patterns in BP (i.e., BP variability) using highly simplified artificial landscapes and wildfire simulation methods. Our results showed that a limited set of inputs yielded a wide range of responses in the mean and spatial patterning of BP. The input factors contributed unequally to mean BP and to BP variability: so-called top-down controls (weather) primarily influenced mean BP, whereas bottom-up influences (ignitions and fuels) were mainly responsible for the spatial patterns of BP. However, confounding effects and interactions among factors suggest that fully separating top-down and bottom-up controls may be impossible. Furthermore, interactions among input variables produced unanticipated but explainable BP patterns, hinting at complex topological dependencies among the main determinants of fire spread and the resulting BP. The results will improve our understanding of the spatial ecology of fire regimes and help in the interpretation of patterns of fire likelihood on real landscapes as part of future wildfire risk assessments.     

Genetic analysis and associated SRAP markers for flowering traits of chrysanthemum (<Emphasis Type="Italic">Chrysanthemum morifolium</Emphasis>)

The inheritance of two flowering traits of chrysanthemum, initial blooming time and the duration of flowering, was investigated using segregation within an F ₁ population derived from a cross between the autumn-flowering ‘Yuhualuoying’ and the summer-flowering ‘Aoyunhanxiao’ cultivars. The analysis, based on a single segregating generation and the major gene plus polygene mixed inheritance model, showed that the inheritance of both traits was compatible with the presence of two pairs of major genes displaying additivity–dominance–epistasis, with additivity predominating. As the heritability of both pairs of major genes was high (initial blooming time ~65%, duration of flowering ~72%), it should be possible to select for both traits in early breeding generations. A marker-trait association analysis based on sequence-related amplified polymorphism (SRAP) genotyping uncovered 10 (initial blooming time) and 12 (duration of flowering) markers significantly associated with phenotype, cumulatively explaining, respectively, 46 and 54% of the variation. Some potentially useful markers were identified.     

Load behaviors of a prefabricated wood framing house during lifting and transportation

Lifting for handling and flatbed truck transportation to the job site are important processes during manufacture of prefabri-cated wooden construction units like mini homes and building modules. Significant damage can occur to sections or components of units during these operations. Although damage usually will not impair its structural safety, it is costly to fix and causes the public to perceive prefabricated wooden buildings as low quality products. Field observations and preliminary numerical models for prefabri-cated units subject to lifting and transportation forces are summarized here. Once fully developed and verified, models will support the creation of damage mitigation strategies centered on structural details indicating how units are to be supported during lifting and transportation.     

花榈木实生苗人工林生长特性研究

花榈木实生苗人工林生长特性研究表明,花榈木适应性较强,在酸性、中性土壤均能正常生长.花榈木前期生长较快,,树高速生期2～7年,年平均生长量57cm,胸径速生期7～15年,年平均生长量0.93cm.材积前期增长较慢,但一直处于上升阶段,第11年生时,材积增长迅速加快,21年后,进入相对稳定的生长高峰期.     

Sample size and power determination for detecting interactions in mixtures of chemicals

In the analysis of mixtures of drugs/chemicals it is often of interest to test for the presence of interaction. If the hypothesis of no interaction (additivity) is not rejected, then the analyst may reasonably claim additivity if and only if the study is powered to a desired (e.g., biologically meaningful) level. The objective of this article is to address the sample size and power issues related to testing the hypothesis of additivity at specified mixture points. The study of disinfectant by-products (DBPs) found in drinking water, described in earlier literature, is used to illustrate the procedures for estimating power and sample sizes for detecting interactions at specified mixtures. The four trihalomethanes used in the study are bromodichloromethane (BDCM), chlorodibromomethane (CDBM), chloroform (CHCl₃), and bromoform (CHBr₃)