Stocking density and its influence on shape of Senegalese sole adults

Morphological changes in Senegalese sole adults (Solea senegalensis Kaup, 1858) reared at two stocking density conditions (low stocking density, 60% of bottom occupation and high stocking density, 180% of bottom occupation) were investigated using geometric morphometrics. Canonical variate analysis on weight matrix scores, including the uniform component (W′), at the end of the experiment revealed differences in body shape between experimental groups. The low density group presented a similar change pattern as that of the high density group but was less intense. Differences were discussed in terms of the effect of a high stocking density on the shape of soles which were very close to commercialization. Results did not indicate a significant size-related shape, likely due to fish age. Our results provide the first promising look at environment-related shape changes in reared sole.     

四川盆地西缘柳杉人工林结构及生长预测的初步研究

运用多元统计分析的方法,研究了四川盆地西缘山地柳杉人工林的密度和直径—株数分布的规律,筛选出了影响林分密度的主导因子(林今年龄、地位指数和林分平均直径),并建立了林分密度预测模型。还根据西泽正久(1978)所提供的求解Weibull分布参数e的gamma和Cud数值表,对48块林令标准地的林木株数调查结果用Weibull分布函数进行了拟合。结果表明:有33块标准地的拟合结果经卡方检验达到极显著水牛(α=0.01),有10块标准地达显著水平(α=0.05),另有5块标准地的拟合结果则不符合weibull分布。在此基础上,对影响柳杉人上林Weibull分布函数的 b、c参数的林分结构因子进行了回归分析,并用易测林分结构因子建立了两个参数的预测模型。 通过建立上述预测模型,作者对柳杉人工林的结构和生长量进行了综合预测。经检验结果表明:本次研究所建立的预测模型达到精度要求,为森林资源预测、森林经营管理、抚育间伐提供科学依据。     

The effects of changing regional Agricultural Knowledge and Innovation System on Italian farmers’ strategies

The aim of this paper is to identify and assess the role played by innovative extension services in affecting farmers’ strategy. More specifically we implement a multivariate probit model to evaluate the effects of different types of extension services introduced by a reform in the domain of Agricultural Knowledge and Innovation System (AKIS) in Italy. The results show that both generalist and specialized services could play a major role in farmers’ value creation strategies. They also confirm that different strategies for creating value are jointly implemented. Finally, they show that a further improvement in the quality of public provision of extension services within regional AKIS and a greater (systemic) interaction between farmers, rural actors and local networks should be supported.     

Structure of the nematofauna in Spanish Mediterranean continental soils

We studied the nematofauna in cultivated Euvisols in the Spanish Central Region in terms of multivariate statistical relationships between nematode groups and environmental variables (habitat, hosts, soil lexture, and quantitative edaphic variables). Three large nematode associations were recognized, one group being characteristic of the region's rotational crops (Pratylenchus, Ditylenchus, Helicotylenchus, Tylenchorhynchus, Rotylenchus, other Dorylaimidae,Plectus, andTylenchus), a second group related to cereal monoculture and wild gramineae associated with bush formations (Heterodera, Criconemoides, Discolaimus, and other Rhabditidae), and a third group characteristic of uncultivated soils (Paratylenchus, Xiphinema, Hemicycliophora, Mononchus, Tripyla, andAlaimus).Paratylenchus andTylenchus species were shown to have an indicator value for certain edaphic properties, especially soil texture, and may be regulated by the clay content of the soil.     

Characterization of Italian and exotic Lathyrus germplasm for quality traits

The aim of the following work is to characterize quality traits (protein, ashes, 100 seed weight and ODAP content) of 117 accessions of Lathyrus, from either Italian or foreign countries. Significant differences among entries were estimated for all traits and accessions were classified into similar genetic groups. Principal component and hierarchical cluster analyses produced five different groups. In particular, the absence of a strong association among the investigated traits and their dominant independent roles in each separate principal component allows the achievement of a useful recombinant in breeding work. An interpretation of each cluster, based on the data obtained from the accessions, provides practical information to establish a subset of grass pea collection for further activities.     

Relationships among different geographical groups,agro-morphology,fatty acid composition and RAPD marker diversity in Safflower (<Emphasis Type="Italic">Carthamus tinctorius</Emphasis>)

Patterns of geographical diversity, and the relationship between agro-morphological traits and fatty acid composition were assessed for 193 safflower (Carthamus tinctorius) accessions representing forty countries. Accessions were assigned to eight groups based on geographical proximity. Cluster and Principal Component analyses were performed to assess patterns of diversity among the accessions and to select the most distant accessions from each of eight groups for analysis of randomly amplified polymorphic DNA (RAPD) markers. There was a large amount of diversity for agro-morphological traits, fatty acid composition, and RAPD markers. Most correlations among different traits were rather low. Plant height showed a positive correlation with days to flowering (r = 0.63**). Palmitic acid was positively correlated with stearic acid and oleic acid values, and negatively correlated with linoleic acid (P < 0.01). Oleic acid and linoleic acid showed a strong negative correlation (r = −0.89**). The first three principal components together explained 59% of the variation, however, neither principal component analysis (PCA) nor marker analysis revealed a clear relationship between diversity pattern and geographical origin. Accessions from some geographical regions tended to group together, such as accessions from South Western Asia, Central Western Europe, and the Mediterranean region. The correlation between the morphological matrix and the genetic matrix based on RAPD markers was not significant (r = 0.027). Wide diversity in safflower germplasm indicates a considerable potential for improving this crop for both agronomic and quality traits.