Contributions to the Analysis of Genotype × Environment Interactions: Theoretical Results of the Application and Comparison of Clustering Techniques for the Stratification of Field Test Sites

For an analysis of cross-classified data sets with rows = genotypes and columns = environments (locations and/or years), existing genotype × environment interactions are of major importance. Differential responses of genotypes (environments) across environments (genotypes) are expressed by these effects. To reduce the impact of these genotype × environment interaction effects, one commonly stratifies genotypes or environments by cluster analysis techniques into homogeneous groups so that interactions within groups are minimized. The present paper presents a comprehensive overview of the numerous procedures for stratification of genotypes or environments by cluster analysis which have been proposed in the literature. In these studies, two different concepts of interaction have been used: the crossover concept of interaction [different rank orders of genotypes (environments) within environments (genotypes)] or the usual statistical concept of interaction (deviations from additivity of main effects in the linear model). For a quantitative characterization of cluster techniques and for a comparison of two different clustering procedures, two parameters are introduced and discussed: measure of resemblance for two classifications and cluster size for one classification.     

Sclerotinia resistance in sunflower: I. Genotypic variations of hybrids in three environments of Argentina

Sclerotinia sclerotiorum infections on sunflower capitula produce white rot, one of the most dangerous diseases sunflower bears in all humid areas. Therefore, disease quantification on developed genetic materials is a very important action in sunflower breeding. Given the horizontal type of resistance these evaluations should be made in different environments. Several hybrids obtained after crossing seven female × seven male sunflower inbred lines in a factorial mating design were evaluated for resistance to white rot in two locations in the southeast of the province of Buenos Aires, Argentina. Disease incidence and the symptom appearance index indicated significant genotypic effects and genotype × environment (G × E) interactions. Genotypic effects were a greater source of variance than the G × E interaction effects. The G × E interactions only represented changes in magnitude. These results were used to identify the best genotypes for both resistance factors. Four hybrids showed low disease incidence values under both artificial and natural infections, of which only two had high values of the symptom appearance index at both locations. These hybrids are considered to have adequate resistance attributes for the ascosporic penetration and the mycelium extension in the capitulum tissue and could therefore be sown in the province of Buenos Aires without increasing risks of S. sclerotiorum attacks.     

A methodology for evaluating a location as a selection site for an international plant breeding program

Summary A method for comparing locations as selection sites based upon their abilities to predict yield and disease reaction over a target region is proposed. The probability of coincidence in selection for a site is defined as the probability for a line selected at the site to be selected at other sites within the region. The probability of divergence in rejection is defined as that associated with regional selection of a line given that is discarded by the site where selection is being conducted. The ideal selection site would maximize the probability of coincidence in selection and minimize the probability of divergence in rejection. The method is illustrated using a set of data from the rice yield nurseries of the International Rice Testing Program for Latin America planted under the rainfed conditions of Central América and México during the period 1978–1984. Five locations were compared for their predictive ability in selecting for the rainfed rice growing region, based on yield and disease reaction. Selection for yield was defined as performance superior to the best check in each location. Selection for disease reaction was based on an index derived from the Standard Evaluation System for Rice for diseases of regional importance. Locations varies 10–15 percent in their selection coincidence with the region for both yield and disease selection criteria applied independently.     

不同生境对人工栽培龙芽稳木的影响简报

试验研究不同生境对人工栽培龙芽木苗木存活率及生长量的影响结果表明,人工栽培龙芽木宜选择半阴坡、郁闭度为30%左右,土壤湿润不积水,疏松肥沃且透气性好,pH值为5.5~6.5的壤土环境。     

作物—CO2环境模拟装置及评价

利用作物—ＣＯ₂环境模拟装置，探讨未来大气ＣＯ₂浓度倍增与作物生长关系的实验研究，已在各国取得不同程度的进展。该文简要综述了近年来国外有关的实验装置概况和发展动向，概述了三种类型装置（封闭式气室、开顶式气室、开放式系统）的结构、性能、特色及其应用，并作出了综合评价。     

基于B/S结构的设施农业信息平台的研究

设施农业信息平台是应用于设施农业领域的基于网络的信息系统。对基于B/S结构的设施农业信息平台进行了研究,阐述了设施农业信息平台中的关键技术以及体系结构,并分析了设施农业信息平台的各个系统功能模块,指出基于B/S结构的设施农业信息平台是可行的。     

Reaction of Oilseed Rape Cultivars to Sclerotinia Stem Rot in Field Environments

Sclerotinia sclerotiorum (Lib.) de Bary, as an ubiquitous phytopathogenic Ascomycete fungus capable of infecting a wide range of plants, has increased in importance for oilseed rape production worldwide in recent years. The objective of this research was to determine the effectiveness of two measurements of disease rating in predicting the field reaction of cultivars to sclerotinia stem rot. One hundred and ten cultivars or lines of oilseed rape were repeatedly evaluated the disease severity index (DSI) and lesion length for their resistance to nine isolates of S. sclerotiorum in two field stations.There were greatly significant differences between two stations, among isolates, among population of cultivars for the disease severity index and lesion length, and also significant station×isolate interaction for lesion length and population×isolate interactions for DSI and lesion length, but interactions of station×isolate for DSI were not significant.Cultivars such as Pomorzanin and Lisek consistently had the lowest disease severity ratings in the field tests. However,most of cultivars were susceptible to sclerotinia stem rot in the field test. A positive correlation between the mean DSI and lesion length was found for both isolates (Sc23 and B1). The correlations ranged from 0.23 to 0.83 at various plots, with nine of the twelve correlations significant. The correlations for disease caused by different fungal isolates were statistically significant difference. These correlations ranged from -0.44 to 0.90, with nine of the thirty-two correlations significant. It indicated that resistance to some isolates was significantly correlated and selection of some varieties for resistance to one isolate appeared to improve resistance to other isolates.     

中国浑善达克沙地生态环境变化研究

在野外调查采样的基础上,利用1987年,1995年和2000年的Landsat7 TM影像,在地理信息技术的支持下,研究了浑善达克沙地近期地表覆被变化的特征.研究结果表明:浑善达克沙地近期有明显的变化,变化的幅度约3%~6%,沙地面积约2.2×104km2,核心区面积约1.2×104km2;浑善达克沙地的分布与主导风向相一致;退化草地、片沙、沙丘等裸沙地是构成景观的主体,破碎化是浑善达克沙地的主要特征.此外,草地和退化草地的相互转化明显,是两种主要的防治类型.     

嫩江中下游湿地生态环境敏感性分析及可持续管理对策

对嫩江中下游湿地生态环境从自然驱动因子:流域地形地貌、地质构造和沉积特征、气候变化和人为驱动因子:人类开垦活动、水利工程等条件下进行了敏感性评价,在此基础上提出了湿地生态环境可持续性管理对策。     

Sortenbedingte Reaktion bei Lolium perenne L. auf systemisch selektiv wirkende Herbizide

Variety-specific reaction of Lolium perenne L. on selective systemic herbicides
The investigation intended to show the specific reaction of different varieties of Lolium perenne on selective systemic herbicides. These results can be regarded as the base for advanced explorations to the described topic. The results may be summarized as follows:
Independent of the stage of growth, the date of application, the dosage and the droplet size there were effects on the forage yield in correlation to the variety and the active ingredient. Measurable yield reductions were presented after CMPP application on the varieties of the late and after the treatment with Asulam on the varieties of the early maturity group. Compared to the maturity group the varietal attribute growthhabit demonstrated no significant effects. The active ingredients MCPB and MCPA presented not any measurable influence on the forage yield of the different varieties. In the main harvest year the yield depressions were manifested clearer than in the seeding year. In the same way the described secondary actions were larger after the treatment in an advanced stage.
Extended investigations should inquire to the causes and secondary effects on the forage quality. Beyond this for variety testings of species with a large distribution and volume it seems remunerative to include questions of herbicides tolerance.