Study of a germplasm collection of loquat (Eriobotrya japonica Lindl.) by multivariate analysis

Loquat species (Eriobotrya japonica Lindl.) originated in China, later was introduced in Japan. However, introduction in Europe occurred much later, in 18th century, it was introduced as an ornamental tree. Since then, the species was very well adapted to the Mediterranean climate, mainly in South East of Spain, where is located more than 50% of total European crop production. A European Project titled ‘Conservation, evaluation and collection of underutilized fruit species’ supported surveys and collection of plant material from these species in the Mediterranean basin countries. One of these surveys resulted in a germplasm collection of loquat established at IVIA, Valencia, Spain. This collection is being extended with new accessions collected across the world, currently the collection have 123 accessions under study. Germplasm management needs first a characterization of the plant material introduced and second diversity studies into the collection that could point out the variability pattern, to establish groups of accessions with similar traits and the most significant variables. These results allow organizing the information gathered for further uses. In this paper, 62 accessions from the IVIA germplasm collection were studied. Results from 43 variables were gathered and data studied by multivariate analysis. The analysis allowed summarizing the data tables with new variables containing most of the information. These results along with those obtained in the coming years will allow define a nuclear collection (minimum number of accessions that contained all the variability present in the collection).     

Variability of three regional sources of germplasm of Tejocote (<Emphasis Type="Italic">Crataegus</Emphasis> spp.) from central and southern Mexico

Tejocote (Crataegus spp.) is a genus of fruit-bearing trees distributed widely throughout Mexico; 13 species are reported for the north and central zones and two or more species may be present in southern Mexico. Accessions of this genus are safeguarded in the Germplasm Bank of Tejocote at the Autonomous University of Chapingo, mainly from three regional sources, i.e. the states of Puebla, Mexico, and Chiapas, including five different species that belong to series Mexicanae and series Crus-galli. They can be morphologically characterized by leaves from different shoot types, flowers and fruits. Multivariate statistical methods were used to elucidate patterns of variation in each of these regional sources. The sources displayed very low intra-source variability. The source from Chiapas showed significant statistical differences in all morphological variables evaluated, as a result, this genetic pool is considered as different from the other two sources. The sources from the states of Puebla and Mexico only differed by 22.79% (with P ≤ 0.05), and thus they could be considered as components of a single genetic pool. The most highly discriminant variables were from the leaf, such as basal angle, petiole length/major axis length ratio, minor axis length/major axis length ratio, and number of veins. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Effect of the thin cell layer technique in the induction of somatic embryos in Pinus patula Schl. et Cham

Pinus patula is a species commonly used for reforestation in Mexico.However,efficient methods for the mass production seedlings are required.Micropropagation particularly by somatic embryogenesis provides an option for the rapid multiplication of high-quality,genetically improved material.This study induces somatic embryogenesis in this species using the thin cell layer(TCL)technique.Two sources of explants(complete immature embryos;lTCL segments from immature embryos)were evaluated.The efficiency of TCL from longitudinal sections[lTCL]and transverse[tTCL]was evaluated.The results show using thin cell layers from immature embryos cultivated in 16 light/8 dark hours achieves induction of somatic embryos.A higher percentage of embryogenic callus was obtained when tTCL segments were used as an explant source.These results produced somatic embryos from tTCL segments of an immature embryo without germinating the seed,making the process more time efficient.In addition,this technique can be used to generate somatic embryogenesis in forest species that have low germination rates.     

Forms and buffering potential of aluminum in tropical and subtropical acid soils cultivated with Pinus taeda L

Purpose

Several interactions between Al and the solid phase of soil influence Al buffering in soil solution. This work evaluated soils cultivated with Pinus taeda L. to determine Al forms in organic and mineral horizons using various extraction methods and to relate acidity with clay mineralogy.

Materials and methods

Organic and mineral horizons of 10 soil profiles (up to 2.1 m deep) in southern Brazil were sampled. Organic horizons were separated into fresh, aged, and fermented/humified litter. The following Al extraction methods were utilized: 0.5 mol L^?1 pH 2.8 CuCl₂–Al complexed in organic matter; 1.0 mol L^?1 KCl–exchangeable Al; water–Al soluble in soil solution; HF concentrated?+?HNO₃ concentrated?+?H₂O₂ 30% (v/v)–total Al. Six sequential extractions were carried out to isolate different forms of amorphous minerals that can buffer Al on soil solution: 0.05 and 0.1 mol L^?1 sodium pyrophosphate; 0.1 and 0.2 mol L^?1 ammonium oxalate; 0.25 and 0.5 mol L^?1 NaOH. Samples of clay were also analyzed by XRD.

Results and discussion

There was a clear effect of litter age on increasing total Al concentration. In the aged litter and fermented and/or humified litter, levels of total Al were 1.4 to 3.8 and 1.5 to 7.8 times greater than in fresh litter, respectively. The CuCl₂ method had higher Al extraction capacity than the KCl method for litter. The lowest Al–pyrophosphate values were observed in the Oxisol, which also had a predominance of gibbsite and the lowest levels of Al–KCl and Al–CuCl₂. There was an inverse relationship between degree of soil weathering and soluble and exchangeable Al in soils. Available Al increased with higher Si proportion in minerals of the clay fraction (2:1?>?1:1?>?0:1).

Conclusions

The worst scenario was soils with the combination of high soluble and exchangeable Al levels and high concentrations of amorphous forms of Al minerals. The best predictors of Al accumulation in the youngest litter horizon were extractions of amorphous minerals with pyrophosphate and NaOH. These extractors are normally used to predict the level of Al buffering in soils. Organic matter had less influence on Al dynamics in soils.

     

Principles for Sustainable Governance of the Oceans

Pressures being exerted on the ocean ecosystems through overfishing, pollution, and environmental and climate change are increasing. Six core principles are proposed to guide governance and use of ocean resources and to promote sustainability. Examples of governance structures that embody these principles are given.     

Skipjack tuna fishery in relation to sea surface temperature off the southern Brazilian coast

Several oceanographic studies have associated tuna fisheries to sea surface temperature (SST) fields, although catch per unit of effort (CPUE) has not shown a clear relationship with SST. However, most results concerned species that occur deep in the water column. In this paper, we present a study on the relationship between SST and CPUE for the skipjack tuna fisheries off the southern Brazilian coast, which take place at the sea surface. We use historical data from the Japanese fleet, which operated in the area from July 1982 to June 1992. Fishing sets occurred only in areas where SST ranged from 17°C to 30°C. Frequency of occurrence vs. SST showed a Gaussian distribution, with highest CPUEs in waters of SST 22°-26.5°C. The relationship between CPUE (or fishing set occurrence) and SST varied seasonally. Largest CPUEs occurred in summer, independently of SST. Therefore, temperature alone could not be used as a determinant of CPUE, suggesting that seasonal variability of other environmental parameters has a stronger effect on the CPUE than does SST. However, when the seasonal cycle was excluded from the data sets, a relationship between the interannual variability of SST and CPUE became apparent. Cross-correlation analysis between CPUE and SST has shown that oscillations in CPUE anomalies precede oscillations in SST anomalies by a month, but the mechanism relating them in this way is unknown.     

Effect of activated charcoal on Brassica oleracea microspore culture embryogenesis

The effect of the addition of a 0.1 ml drop of activated charcoal (AC) on microspore culture embryogenesis was studied in nine morphotypes of Brassica oleracea. Embryo yields were significantly increased in all of the morphotypes by the addition of the 0.1 ml drop of AC to the microspore culture media. The magnitude of the response to the addition of AC varied with the different plants and morphotypes. The addition of AC never produced a detrimental effect. A qualitative improvement of the subsequent development of embryos to plants was also observed with the addition of AC. Data suggest that the addition of AC to microspore culture media promoted embryo production in different B. oleracea morphotypes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Pacific sardine (Sardinops sagax, Jenyns 1842) landings prediction. A neural network ecosystemic approach

In this study the performances of computational neural networks (CNNs), multiple linear regressions (MLRs) and generalised additive models (GAMs) to predict Pacific sardine (Sardinops sagax) landings and to analyse their relationships with environmental factors in the north area off Chile were studied. For this purpose several local and global environmental variables and indexes (sea surface temperature, sea level and Ekman transport index in the Chilean coast and, sea surface temperature in the area Niño 3 + 4 and Niño 1 + 2, and the south oscillation index) were considered as inputs or independent variables. Additionally, several CNNs were calibrated and validated adding the anchovy (Engraulis ringens) landings in the same area as model inputs. The time lags of the variables considered were selected through analysis of the non-linear cross-correlation functions and an alternative form of sensitivity analysis based on the approach of the missing value problem. The analysis of error measures with validation data set showed that the best results were obtained when local and global variables were used separately and combined with anchovy landings. Globally, the best result was given by a CNN with 18 input variables (model CNN 6(II) which only considered global variables and anchovy landings) and 10 neurons in a hidden layer. For this configuration the explained variance was slightly higher to 86% which supposed a standard error of prediction of 7.66%. These results were significantly better than those obtained with MLRs and GAMs. The strong correlation between predicted and observed sardine landings suggests that CNNs captured the trend of the historical data. Also, the generalisation capacity together the sensitivity analysis allowed us to identify the variables with a high weight in the model and partially to interpret the statistical functional relationships between these environmental variables and sardine landings.     

Sperm quality of Brazilian flounder Paralichthys orbignyanus throughout the reproductive season

The aim of this study was to evaluate the sperm quality of Brazilian flounder Paralichthys orbignyanus throughout its reproductive season. Sperm was collected at the beginning, middle and end of the breeding period. Spermatozoa density was maximum at the beginning (12.7 ± 0.92 × 10⁹ cells mL^?1) and at the end (11.8 ± 0.39 × 10⁹ cells mL^?1) of the breeding season (P<0.05). Sperm production and the percentage of spermatozoa moving fast forward increased significantly towards the end of the breeding season (P<0.05). The mean duration of progressive motility of spermatozoa was around 10 min. No difference was observed during the reproductive season in the percentage of motile cells, pH, osmolality and K⁺, Cl^? and Mg²⁺ concentrations in seminal plasma. The concentration of Na⁺ increased throughout the breeding season, reaching 174.62 ± 12.68 mmol L^?1 at the end (P<0.05). There was a decline in the concentration of Ca²⁺ (12.31 ± 3.08 mmol L^?1) in the middle of the breeding season, which coincided with the shortest motility duration of spermatozoa. The information reported in this study should help to improve management and optimize the development of protocols for short‐term storage and cryopreservation of Brazilian flounder semen.