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21.
Homozygous mlo -barley plants are resistant to barley powdery mildew but hypersusceptible to the rice blast fungus Magnaporthe oryzae . A mutational analysis was performed in the barley back-cross line BCIngrid mlo5 which led to the identification of two mutants with enhanced capacity to resist infections by M. oryzae , referred to as enhanced M. oryzae resistance mutants emr1 and emr2 . Here, we report on the characterization of emr2 mutant plants which not only show an almost complete reduction in disease severity after inoculation with M. oryzae but are also resistant to the necrotrophic fungi Drechslera teres and Rhynchosporium secalis . Histological analysis revealed that resistance to M. oryzae was based mainly on the formation of papillae at sites of attempted penetration into epidermal cells. There was no progression of fungal growth into the mesophyll. Additionally, because of the presence of the mlo -allele, emr2 -plants retained resistance to powdery mildew. The emr2 -conditioned broad spectrum resistance was inherited as in a recessive manner. Monitoring of PR -gene expression and enzymatic activity of peroxidases revealed a constitutively activated defence in emr2 . 相似文献
22.
N. Thangthong S. Jogloy N. Jongrungklang C. K. Kvien V. Pensuk T. Kesmala N. Vorasoot 《Journal of Agronomy and Crop Science》2018,204(2):111-122
Drought severely limits crop yield of peanut. Yet cultivars with enhanced root development enable the exploration of a greater volume of soil for water and nutrients, helping the plant survive. Root distribution patterns of three genotypes (ICGV 98305, ICGV 98324 and Tifton‐8) were compared when grown in well‐watered rhizoboxes and when grown in rhizoboxes where an early‐season drought was imposed using rain‐exclusion shelters. The treatments were arranged in a completely randomized design with three replications, and the experiment was conducted during two seasons at the Field Crop Research Station of Khon Kaen University, in Khon Kaen, Thailand. The root system of ICGV 98305, when grown under drought, had a significantly higher root length in the 30–110 cm deep soil layers and less roots in the 0–30 cm soil layers when under drought than when grown under well‐watered conditions. Roots of Tifton‐8 had the largest reductions in root length in upper soil layer and reduced in most soil layers. Tifton‐8 grown under drought was smaller than under well‐watered control for all root traits, showing negative response to drought. The peanut genotypes with high root traits in deeper soil layer under early‐season drought might contribute to drought avoidance mechanism. 相似文献
23.
R. I. Muetzelfeldt 《Agroforestry Systems》1995,30(1-2):223-234
There are a number of problems with conventional methods for implementing models of agroforestry systems, including the difficulties of building, modifying and understanding them. One way of addressing these problems is to adopt a modular modelling approach, in which a model is constructed by linking a number of submodels, which in turn may consist of smaller computational units.This paper presents a basic framework for the design of a modular modelling approach suitable for agroforestry modelling. This approach is based on a close correspondence between the notion of module in modelling and of subroutine in a programming implementation of a model, so that selecting and linking modules is analogous to choosing and issuing calls to subroutines. This approach has the potential for enabling the complex modelling structures that are required for agroforestry modelling, such as spatial aspects and the representation of individual trees, to be handled in a consistent and uniform manner.The approach requires that subroutines should be held as symbolically-represented structures, rather than just source code in a programming language, so that they can be referenced as discrete units, and internally modified by symbol-processing operations. It is shown that the logic-programming language Prolog is well-suited to the task of representing subroutines in template form, ready to be fleshed out and combined into a single program in response to the selections made by a user. Prolog's suitability for the development of a user-friendly model design interface is also discussed, enabling models to be constructed simply by selecting options from a menu of design choices. 相似文献
24.
In Accelerated Recurrent Selection (ARS) schemes, selection is based on the predicted performance of progeny families, estimated as the average of the parental families. These schemes can halve cycle time compared to simple recurrent selection methods. They also have a lower requirement for evaluation of families in yield trials, although they do require more seed production. ARS therefore provides options in cycle time, effective population size, response to selection and cost which have not been available before. Example schemes are compared by computer simulation with truncation selection and with optimal family selection, where contributions of families to the next generation are optimised to give the maximum response to selection at a specified effective population size. In many circumstances, ARS schemes compare favourably. Difficulties in combining estimates of selection intensity and of effective population size when comparing the merits of different breeding schemes are discussed. It is suggested that unless one is interested in response to selection over periods greater than 50 years, the weight given to effective population size in ranking different schemes should be small. 相似文献
25.
O. A. A. Lopes de Sá M. A. S. Lara A. R. Evangelista T. F. Bernardes D. R. Casagrande 《Grass and Forage Science》2015,70(2):335-340
Understanding the morpho-physiological responses of forage plants is critical for successfully managing pastures; however, there is no specific method for morphogenetically assessing Arachis pintoi. The present study aimed to develop and validate mathematical models to estimate leaf area in A. pintoi to enable assessments of leaf elongation and senescence. Two experiments were performed. The first experiment used 500 A. pintoi leaves to model leaf area. Three models were used: correlation, mechanistic and empirical. A total of 336 leaflets were collected to validate the models. For the second experiment, 786 leaflet pairs were collected to test the leaf symmetry. Leaf length (L), width (W) and area (A) were measured for each leaflet in both of the experiments. The model identity test was used. The leaflet area can be estimated using the following formula: Â = W ×L × 0·25 × π. Experiment 2 showed that the initial leaflet pairs were equal, as were the terminal leaflet pairs. In conclusion, the mechanistic model should be used to estimate the leaf area for A. pintoi, and only half of each leaf can be measured. 相似文献
26.
First-fortnight incidence (FFI) is a modelling parameter that can be used to predict both the prevalence and duration of a foot-and-mouth disease (FMD) epidemic at regional and national levels. With an indication of how long an epidemic may last by the end of week two, it becomes possible to estimate whether vaccination would be economically viable from the start of an epidemic. Where FFI indicates that an epidemic is unlikely to last for as long as an export ban on agricultural produce, it may be inappropriate to implement a policy of 'vaccination to live'. Alternatively where FFI indicates that an epidemic will equal or exceed the ban length, then the benefits of vaccination should be considered at an early stage, during or after the first fortnight. Since blanket vaccination of the national or regional herds and flocks would be both costly and heighten the risk of producing carrier animals, targetting vaccination through risk assessment becomes useful. 相似文献
27.
Divergent selection for heading time was performed in two F2 barley population. Five populations were obtained for each cross: F5 SSD (unselected control), 3E and 3L (from three cycles of selection for earliness or lateness), 2E1L and ZL1E (from two cycles of direct and one of reverse selection). These populations, together with corresponding parents and F2 generations, were evaluated over two years. The response to selection was 5.6 and 6.5 days inane direction (earlier heading) and 7.7 and 6.7 clays in the other direction (later heading) in the two crosses, respectively. 3E and 3L populations were highly transgressive as compared to their parents. A sizeable amount of genetic variability was still present after two cycles of selection. Heading was probably controlled by a polygenic system with prevailing additive effects and alleles for earliness and earliness somewhat equally distributed in the parents. Selection fur heading time led to significant changes in plant height, yield and kernel weight. Early progenies were higher yielding than lace ones. 相似文献
28.
Daniel Ovando;Darcy Bradley;Echelle Burns;Lennon Thomas;James Thorson; 《Fish and Fisheries》2024,25(2):218-234
Designing effective spatial management strategies is challenging because marine ecosystems are highly dynamic and opaque, and extractive entities such as fishing fleets respond endogenously to ecosystem changes in ways that depend on ecological and policy context. We present a modelling framework, marlin, that can be used to efficiently simulate the bio-economic dynamics of marine systems in support of both management and research. We demonstrate marlin's capabilities by focusing on two case studies on the conservation and food production impacts of marine protected areas (MPAs): a coastal coral reef and a pelagic tuna fishery. In the coastal coral reef example, we explore how heterogeneity in species distributions and fleet preferences can affect distributional outcomes of MPAs. In the pelagic case study, we show how our model can be used to assess the climate resilience of different MPA design strategies, as well as the climate sensitivity of different fishing fleets. This paper demonstrates how intermediate complexity simulation of coupled bio-economic dynamics can help communities predict and potentially manage trade-offs among conservation, fisheries yields and distributional outcomes of management policies affected by spatial bio-economic dynamics. 相似文献
29.
响应面法优化鲈鱼鱼松加工工艺 总被引：2，自引：0，他引：2
为丰富淡水鱼精深加工品种,以大口黑鲈(Micropterus salmoides)为原料,制备一种鱼松。通过单因素优化腌制时间、汽烹时间和干制时间3个关键工艺参数。利用响应面分析方法,建立感官评分与工艺参数间的模型,确定鱼松的最优工艺参数。结果表明,影响感官分数的因素排序依次为干制时间腌制时间汽烹时间。采用响应面分析法建立的模型,曲面方程拟合性好,其优化的鱼松最佳工艺参数为腌制时间1.01 h,汽烹时间18.04 min,干制时间2.44 h。此条件下感官分数达8.92,与模型方程理论预测值(9.07)相对误差为1.65%。产品鉴定出挥发性物质成分27种,主要为烷类、烯类、苯类和酮类。本试验鱼松产品呈疏松的浅黄色絮状,味道鲜美,可进一步工业化生产。 相似文献
30.
Sara Ringmark Arne Lindholm Ulf Hedenstr?m Michael Lindinger Kristina Dahlborn Clarence Kvart Anna Jansson 《Acta veterinaria Scandinavica》2015,57(1)