Land-use change arising from rural land exchange: an agent-based simulation model     

Martha M. Bakker  Shah Jamal Alam  Jerry van Dijk  Mark D. A. Rounsevell 《Landscape Ecology》2015,30(2):273-286

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A probabilistic eco-hydrological model to predict the effects of climate change on natural vegetation at a regional scale     

Jan-Philip M. Witte  Ruud P. Bartholomeus  Peter M. van Bodegom  D. Gijsbert Cirkel  Remco van Ek  Yuki Fujita  Gijs M. C. M. Janssen  Teun J. Spek  Han Runhaar 《Landscape Ecology》2015,30(5):835-854

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Impacts of agricultural changes in response to climate and socioeconomic change on nitrogen deposition in nature reserves     

J. Kros  M. M. Bakker  P. Reidsma  A. Kanellopoulos  S. Jamal Alam  W. de Vries 《Landscape Ecology》2015,30(5):871-885

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Functional genomics of microspore embryogenesis     

Julia Hosp  Simone Faria de Maraschin  Alisher Touraev  Kim Boutilier 《Euphytica》2007,158(3):275-285

Isolated plant microspores, when stressed and cultured in vitro, can be diverted from their normal gametophytic pathway towards sporophytic development, with the formation of haploid embryos and ultimately doubled-haploid plants. This process is called androgenesis or microspore embryogenesis, and is widely used in plant breeding programmes to generate homozygous lines for breeding purposes. Protocols for the induction of microspore embryogenesis and the subsequent regeneration of doubled haploid (DH) plants have been successfully developed for more than 200 species. These practical advances stand in stark contrast to our knowledge of the underlying molecular genetic mechanism controlling this process. The majority of information regarding the genetic and molecular control of the developmental switch from gametophytic to sporophytic development has been garnered from four intensely studied (crop) plants comprising two dicotyledonous species, rapeseed (Brassica napus) and tobacco (Nicotiana tabacum), and two monocotyledonous species, wheat (Triticum aestivum) and barley (Hordeum vulgare). In these species the efficiency of microspore embryogenesis is very high and reproducible, making them suitable models for molecular studies. In the past, molecular studies on microspore embryogenesis have focussed mainly on the identification of genes that are differentially expressed during this developmental transition and/or early in embryo development, and have identified a number of genes whose expression marks or predicts the developmental fate of stressed microspores. More recently, functional genomics approaches have been used to obtain a broad overview of the molecular processes that take place during the establishment of microspore embryogenesis. In this review we summarise accumulated molecular data obtained in rapeseed, tobacco, wheat and barley on embryogenic induction of microspores and define common aspects involved in the androgenic switch.  相似文献   

Formalizing agro-ecological engineering for future-oriented land use studies   总被引：2，自引：0，他引：2  

H. Hengsdijk  M. K. van Ittersum 《European Journal of Agronomy》2003,19(4):549-562

Agriculture faces an array of interrelated problems that call for development of new and revision of existing cropping systems towards the multiple needs of the 21st century. Agro-ecological engineering approaches aimed at design and exploration of alternative land use systems at various scales may support the identification of appropriate land use options. Engineering approaches are based on mathematical representations of well-founded agro-ecological principles while taking into account available resources and prevailing land-related objectives. The goal of this paper is to contribute to the development of a formalized approach to engineer cropping systems at the land unit level that can be used as building blocks for systematic explorations of land use options at farm or regional scale. The approach for engineering cropping systems at the land unit level consists of three steps: (i) goal-driven design of cropping systems, (ii) quantification of biophysical production targets and (iii) definition of the optimal mix of inputs required to realize production targets. This paper describes the approach and illustrates it with examples from the Sudano-Sahelian zone of Mali. Explicit attention is paid to the required numerical tools and their application to analyze consequences of uncertainty in the performance of engineered cropping systems. Using numerical tools, uncertainty is made explicit with the aim to better manage or reduce it. Identification of uncertainty at the designer's desk allows taking uncertainty into account before applying engineered land use systems in regional model studies or testing such systems in practice. Problems related to the application of numerical tools are discussed, including the future role of agro-ecological engineering as independent discipline within agricultural science.  相似文献   

Cytoplasmic male sterility in petunia. II. A discussion on male sterility transmission by means of grafting     

G. A. M. van Marrewijk 《Euphytica》1970,19(1):25-32

Summary The aim of this study was to explore any possible mutual influence after grafting cytoplasmic male sterile and fertile petunia plants. In the graft generation no mutual influence of the graft partners was observed and progeny obtained by self- or cross-fertilizing graft components did not provide convincing indications as to sterilizing or fertilizing influence. Reduced fertile or even male sterile flowers were sometimes observed on some descendants of fertile graft components, but in all cases they had to be ascribed to causes other than sterility transmission.Critical analysis of the results and conclusions drawn by other authors infer that they have not conclusively shown sterility transmission by grafting either.  相似文献   

Prototyping and farm system modelling—Partners on the road towards more sustainable farm systems?     

B. Sterk  M.K. van Ittersum  C. Leeuwis  F.G. Wijnands 《European Journal of Agronomy》2007,26(4):401-409

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氮硫交互作用对小麦苗期生长和养分吸收的影响   总被引：15，自引：1，他引：15  

刘宝存  孙明德  吴静  黄德明 《华北农学报》2002,17(3):90-93

通过基质盆栽冬小麦，研究了氮硫交互作用对小麦苗期生长及养分吸收的影响。研究结果表明，氮、硫对苗期小麦的生长都有一定影响，氮的增产效果远大于硫，当氮肥用量为200mg/盆时，小麦生物量的最大增产幅度89％；在低氮水平下，硫肥的增产效果最佳，最高可增产125。硫肥的施用可以提高苗期小麦植株体内硫的累积量，在氮素胁迫的情况下最为显著，可提高1倍以上；同时降低植株体内氮的累积，但降低幅度不大。氮素充足时，地上部与地下部生物量之比为2.4-3.9，氮素胁迫条件下，小麦的地上部和地下部的生物量相当，说明氮素养分不足时，小麦合成的有机物质更倾向于分配给根系，促进根系的生长，这可能是小麦抵抗胁迫环境条件的生理机制之一。  相似文献   

The phylogenetic relationship between different Cichorium intybus cultivars and cultivar groups, as revealed by RAPDs     

N. Van  Stallen  V. Noten    V. Neefs  M. de  Proft 《Plant Breeding》2001,120(5):425-428

The phylogenetic relationship between different Cichorium intybus cultivars and cultivar groups was studied. A total of 127 random amplified polymorphic DNA markers have been used to distinguish between 51 Cichorium intybus cultivars belonging to three different cultivar groups. A principal component analysis was performed on the complete data set and a clear grouping of chicory cultivar groups was observed. The three chicory groups tested (root chicory, witloof and pain de sucre) were separated from one another in the principal component plots. The first two axes accounted for 43.9% of the total variation. Although the chicory used in traditional forcing in soil and the red chicory cultivars were related more to each other and to the chicory cultivars from the witloof group, they still formed separate groups in the principal component plot.  相似文献   

Molecular genetic characterisation of the Asc locus of tomato conferring resistance to the fungal pathogen Alternaria alternata f. sp. lycopersici     

E. A. van der Biezen  B. Overduin  T. J. A. Kneppers  L. A. Mesbah  H. J. J. Nijkamp  J. Hille 《Euphytica》1994,79(3):205-217

The Alternaria stem canker disease of tomato is caused by the fungal pathogen Alternaria alternata f. sp. lycopersici and its host-selective AAL-toxins. Resistance to the pathogen and insensitivity to the toxins are conferred by the Asc locus on chromosome 3L. Sensitivity to AAL-toxins is a relative character; the toxins inhibit development of all tested tomato tissues but susceptible cultivars are much more sensitive than resistant cultivars. In addition to tomato, some other plant and animal species are sensitive to the toxins as well. The likely mode of action of AAL-toxins is interference with sphingolipid biosynthesis by specific inhibition of ceramide synthase activity. To molecularly isolate Asc, transposon tagging and positional cloning strategies are applied. As a first step, transposon insertions and restriction fragment length polymorphism (RFLP) markers are identified in proximity of the Asc locus. Subsequently, the transposons are used to inactivate Asc by insertion mutagenesis, and the RFLP markers are used to identify yeast artificial chromosomes (YACs) with tomato DNA inserts. Once an Asc-insertion mutant and/or a YAC encompassing Asc has been obtained, physical isolation and characterisation of Asc will be conceivable. Elucidation of the molecular role of Asc will illuminate the specificity of host recognition by Alternaria alternata f. sp. lycopersici.Abbreviations AAL-toxin Alternaria alternata lycopersici-toxin - A. a. lycopersici Alternaria alternata f. sp. lycopersici - Asc Alternaria stem canker - HST host-selective toxin  相似文献