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| Seminars |
Welcome to the Crop and Soil Sciences Seminar Series. Following is a list of the seminars scheduled for the Fall of 2001. Unless otherwise noted, all seminars are on Tuesdays, from 3:30 PM to 4:30 PM in 135 Emerson Hall.
2002 Graduate Student Symposium - 5/6/2002
Crop and Soil Sciences
1/29/02 - Getting Started Quickly: Crop Establishment and On-farm Seed Priming (Dr. David Harris, Senior Research fellow, Crop Physiology/Adaptive Research Manager, Centre for Arid Zone Studies, University of Wales, Bangor, UK). Abstract: Dr. David Harris is a Senior Research Fellow and Manager for Crop Physiology/ Adaptive Research in DFID's Plant Sciences Research Programme at the Centre for Arid Zone Studies; University of Wales, Bangor, UK. He has over 20 years experience working on adaptive research, on-farm evaluations of technology, crop physiology, extension methodology and and soil/water management. Dr. Harris' international postings have included India, Botswana, Zimbabwe, and the East Caribbean. He will discuss his research with on-farm seed priming,, a simple, low input and highly effective technology to improve the livelihoods of resource-poor farmers in marginal environments.
Individual meetings with Dr. Harris can be scheduled for Jan 28-Jan 30(am only) with Julie Lauren, Dept. of Crop and Soil Sciences; 5-1727; JGL5@cornell.edu
2/19/02 - Bangladesh: From Basket Case to Bread Basket (Dr. Craig Meisner, Adjunct Associate Professor, Department of Crop & Soil Sciences) Abstract: A brief history of the agriculture research and development of Bangladesh will be presented, illustrating that the impacts of the CGIAR centers might have had on cereal production. A short discussion on lentil and pulse production declines will follow showing they may NOT have resulted from the impacts of cereal production increases but perhaps due to their environmental risk. A review of CIMMYT's work in Bangladesh during the past years will be presented showing its integration with the academic research by Cornell University through the Soil Management CRSP Phase II, SRI, Arsenic, Papaya Improvement and the alleviation of Ca- deficiency induced rickets. Craig is an Agronomist
2/26/02 - When, And at What Scale, Does Soil Heterogeneity Matter? (Philippe Baveye, Associate Professor, Department of Crop & Soil Sciences) Abstract: Since the late 60s, soil heterogeneity (also referred to as "soil variation" or "soil variability") has been the object of considerable attention from soil and environmental scientists. Interest in the subject waned slightly in the late 80s but made a remarkable come-back since, in particular through applications of GIS and demands from the "precision" agriculture movement. In this general context, the present talk will propose a critical reflection on recent research trends related to soil heterogeneity. Specifically, it will address (1) the common lack of a clear and explicit justification of much of the research on the topic, (2) the often-ignored relativist (i.e., observer-dependent) nature of the concept of soil heterogeneity itself, and (3) the fact that small-scale heterogeneity (which may crucially affect, e.g., biological activity, soil ecotoxicology, and plant nutrition) is generally ignored. The discussion will be illustrated by experimental results obtained by the author in a number of recent and current projects. Perspectives will be proposed for future research efforts.
4/2/02 - Highlights of Thirty-Year History in Classical Biological Weed Control (Neal R. Spencer, USDA/ARS Entomologist) Abstract: In the native home (or region of origin) of a given plant species, there should exist natural enemies which maintain (or are capable of maintaining) a comparatively low population density of the plant. This action is called classical biological control and is the reason why so many of our native plant species are relatively rare and/or innocuous. Classical biological weed control researchers look for host-specific natural enemies in the area of origin of the targeted weed and, working within a government-controlled framework, import the organisms into the United States. Canada, Australia, New Zealand, South Africa and the Commonwealth Agriculture Bureau International (CABI) Biosciences have been leaders in biological weed control for many years. The United States has not emphasized biocontrol, but as concern increases over the impact of exotic invasive species on North America and the large scale use of chemical herbicides, ecological management strategies will be a part of the integrated pest management (IPM) toolbox. A thirty year history of biological weed control will be given using specific weed programs covering different areas of the United States.
4/9/02 - DNA Microarray Analysis of Transcriptional Profiling of Developing Maize Kernels in Response to Water Deficit (LongXi Yu, Research Associate, Crop and Soil Sciences Department, Cornell University) Abstract: Although the early reproductive stages of maize kernel development have long been recognized as being particularly vulnerable to water deficit and causes stress-related yield loss, the mechanistic bases of the response are still not fully understood. Our work has focused on water deficit after fertilization is complete, during the period of rapid endosperm cell division. Also during this period, the development of placenta and vascular tissue of the pedicel creates capacity for influx of sugar and signaling molecules. Water deficit during the first few days after pollination inhibits early endosperm cell division, resulting in abortion of kernel development. To gain a better understanding of the regulatory mechanisms involved, we have initiated a functional genomics approach using DNA microarray technology. With the ZmDB endosperm and ear tissue arrays, we have probed mRNA targets of maize endosperm and pedicel/placenta in plants subjected to drought stress episodes and in unstressed controls. Targets were labeled with cyanine-3 and cyanine-5 and then hybridized competitively within a single array. Microarray data were obtained from replicated experiments and analyzed using a series of computer software. Since the plant hormone abscisic acid (ABA) plays a critical role in response to water deficit, we have used the kinetics of ABA accumulation in developing kernels and leaf water potential as indicators of the stringency of the stress treatments.
4/16/02 - Model Evaluation by Comparison of Model-Based Predictions and Measured Values (Gary Fick, Professor, and Hugh Gauch, Research Support Specialist, Crop and Soil Sciences Department, Cornell University) Abstract: Model evaluations, accurate predictions, and comparisons of multiple models require appropriate statistical procedures. Until recently, those procedures were so poorly defined that several different approaches were employed to evaluate predictive models. In this seminar, three distinct components of discrepancies between model-based and measured values are defined: unequal means, nonunity of slope, and lack of correlation. Mean squared deviation (MSD) is responsive to all three components, but regression and correlation are responsive to only the third component. These three MSD components are statistically independent, distinct, and additive. Also, their meanings relate directly to the usual regression parameters, namely the intercept a … 0, slope b … 1, and squared correlation r2 …1. A mathematical proof shows that the usual regression of Y on X provides the most accurate predictions of Y regardless whether there is error in X only (as this regression assumes) or in Y only or in X and Y both (as other regressions assume). Finally, multivariate analysis using the Additive Main effects and Multiplicative Interaction (AMMI) model provides a complementary and comprehensive overview when there are several sets of model-based values rather than just one, or likewise when there are several sets of measured values, or both. In conclusion, effective model evaluation uses complementary statistical methods: MSD components, linear regression, and multivariate analysis.
4/23/02 - Galactosyl Cyclitol Accumulation Enhanced by Substrate Feeding of Soybean Embryos (Silvia Odorcic, Undergraduate Research Assistan, Seed Biology, Crop and Soil Sciences Department, Cornell University) Abstract: Soybean (Glycine max (L.) Merrill) seeds accumulate soluble carbohydrates, primarily sucrose, raffinose, and stachyose and lesser amounts of galactopinitol A, galactopinitol B, ciceritol, and fagopyritol B1 in axis and cotyledon tissues as part of the seed maturation process. By contrast somatic embryos appear to be deficient in D-pinitol and galactopinitols indicating a lack of biosynthesis by embryo tissues. Cyclitol feeding experiments were performed with immature soybean embryos followed by slow drying to evaluate the role of substrate availability on the accumulation of galactosyl cyclitols during precocious maturation. D-Pinitol, myo-inositol, D-chiro-inositol and sucrose were fed individually or in combinations in both concentration series experiments and in slow drying time experiments. Sucrose feeding resulted in initially high levels of sucrose that declined during precocious maturation. myo-Inositol feeding resulted in a transient doubling of galactinol but had little effect on free myo-inositol, raffinose, stachyose, or other soluble carbohydrates. D-Pinitol feeding increased free D-pinitol 8 fold, galactopinitol A 4.5 fold and galactopinitol B 4.2 fold. Galactopinitols may be effective galactosyl donors for the biosynthesis of raffinose and stachyose. Feeding D-chiro-inositol increased fagopyritol B1 17 fold in axis and 7 fold in cotyledons accompanied by a decrease in free D-chiro-inositol, but did not increase D-pinitol, myo-inositol, galactopinitol A, galactopinitol B, galactinol, raffinose or stachyose concentrations. These results suggest that D-chiro-inositol does not serve as precursor to other cyclitols in soybean embryos and fagopyritol B1 does not serve as an alternate galactosyl donor for the biosynthesis of raffinose and stachyose. Feeding combinations of D-pinitol and D-chiro-inositol resulted in product accumulation patterns as feeding each alone and without interference. Results of these substrate feeding experiments are consistent with the interpretation that D-pinitol and D-chiro-inositol are transported from maternal tissues and not biosynthesized in soybean embryo tissues, that galactopinitols and fagopyritol B1 are biosynthesized by different pathways in soybean, that galactopinitols are biosynthesized by stachyose synthase, that fagopyritol B1 is biosynthesized by galactinol synthase in soybean, and that galactopinitols may serve as galactosyl donors for stachyose biosynthesis.
4/30/02 - Two Seminars presented at the Spring Undergraduate Research Forum 2002
Response of Extracellular Enzyme Activity to Phosphorus Addition in Two Calcareous Fens (Benjamin E. Wolfe and Carmen T. Chapin, Department of Natural Resources, Cornell University) Abstract: Recent work has established the suitability of enzymatic assays in assessing biogeochemical alterations and subsequent changes of plant communities within wetland ecosystems. As part of a long-term study of the phosphorus (P) biogeochemistry of calcareous fens of Central New York, we measured the response of soil alkaline phosphatase to the addition of different forms of organic and inorganic P within the rhizosphere of the plant community. In an in situ fertilization experiment, the p-nitrophenol alkaline phosphatase assay was used in lab to measure differences in alkaline phosphatase activity (APA) between control plots and P enrichment plots. Following the field experiment, we supplemented our investigation with a laboratory incubation experiment to determine if the lack of enzyme activity inhibition was due to sub-critical levels of P addition. Soil from the field site was incubated with similar and different amounts and forms of labile (ortho) P. Our results indicate that the response of the microbial community depends on limitations within the microbial pool and not just on perceived limitation of the ecosystem as it pertains to the plant community.
The Effect of Lime and Phosphorus on Nodulation of the Leguminous Trees, Inga Edulis and Gliricidia Sepium in Amazonian Agroecosystems (Jessica Milgroom, Honors Thesis Work, Department of Crop & Soil Sciences, Cornell University) Abstract: The Amazon rainforest is rapidly being converted to farmland and pasture. Many efforts are underway to understand the ecology of reforestation of deforested areas and the sustainable management of associated agroecosystems. Nitrogen-fixing trees in small-scale agricultural systems play an important role in maintaining and restoring soil fertility via minimizing soil erosion and nutrient leaching, and enhancing biological N fixation. Trees in agricultural systems also provide fruits, fuelwood and fodder. This study focused on two N-fixing species, Inga edulis (native) and Gliricidia sepium (exotic) that are ubiquitous in forests margins as well as on farms. The low levels of available Ca and P in local soils can severely restrict root growth, nodulation and N-fixation. I investigated the effect of fertilizer treatments: phosphorus, lime and phosphorus + lime on nodulation of I. edulis and G. sepium in a 2x2 randomized blocks field experiment 54km north of Manaus, Brazil. In addition, two methods: soil auguring and trenches were compared for quantifying nodulation of I. edulis and local farmers were surveyed about their knowledge and uses of Inga. Results showed that additions of lime (Ca) significantly increased total number of nodules of I. edulis and there was a significant interaction effect between P and Ca in terms of nodule biomass for I. edulis. In comparing G. sepium and I. edulis, P had a significant positive effect on nodule biomass and activity and there was a significant interaction effect with species. The augur method cannot be used to predict nodulation values found with the trench method. All but three of 24 farmers interviewed cultivated species of Inga, mainly for fruit and shade purposes.
Special Seminars
2/14/02 - Sustainable Agriculture in Vermont (Dr. Vern Grubinger, Director of Sustainable Agriculture, University of Vermont). The talk will be focusing on the multiple components of sustainable farming in Vermont, from field practices to marketing. Room 404, Plant Science, 4 PM. Refreshments afterwards. Sponsored by the Department of Horticulture Graduate Students and the GSSAFC.
3/1/02 - Improving Crop Productivity and Sustainability of the Rice-Wheat Cropping System in South Asia: Highlights from 5 Years of the Soil Management CRSP Program (John Duxbury, Professor, Department of Crop & Soil Sciences) Abstract: John Duxbury, a Crop and Soil Sciences faculty member for 32 years, was trained as an organic chemist, but later switched his emphasis to working with agricultural systems. His research has covered a range of topics from greenhouse gas fluxes to soil nutrient dynamics and more recently, factors affecting the productivity and sustainability of the rice-wheat cropping system in South Asia. Dr. Duxbury, who has worked extensively in developing countries on a range of agricultural and environmental issues, also has a growing interest in food systems approaches to addressing human nutrition and health problems in South Asia.
CO_SPONSORS: Cornell Agroforestry Working Group, Management of Organic Inputs in Soils of the Tropics, and the Department of Crop and Soil Sciences. 135 Emerson Hall, 12:20-1:10 PM. Refreshments provided.
3/7/02 - Genetic Modification and Agriculture: Science, Risks, Ethics, and Public Policy (Dr. Jules Pretty, Director, Center for Environment and Society, Universtiy of Essex, UK) Sponsored by the Department of Horticulutre. G10 Biotechnology Building, 4:00 PM. Refreshments provided.
4/12/02 - Predicting Exposure to Aromatic Hydrocarbons in Industrial Soils: Understanding standard analytical methods and their relevance to risk assessment (Joe Kreitinger, Department of Crop and Soils Sciences, Cornell University, The Retec Group, Inc. www.retec.com) 300 Rice Hall, 12:20 to 1:10 PM. Sponsored by Environmental Toxicology, Cornell Center for the Environment.
Conferences
Other Related Seminars
CAWG/MOIST Seminar Series - Organic Inputs and Agroforestry