Automated irrigation of apple trees based on measurements of light interception by the canopy     

Jaume Casadesús  Mercè Mata  Jordi Marsal  Joan Girona 《Biosystems Engineering》2011,108(3):220-226

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Polycyclic Aromatic Hydrocarbons in Soils from European High Mountain Areas   总被引：1，自引：0，他引：1  

Roberto Quiroz  Joan O. Grimalt  Pilar Fernandez  Lluis Camarero  Jordi Catalan  Evzen Stuchlik  Hansjoerg Thies  Ulrike Nickus 《Water, air, and soil pollution》2011,215(1-4):655-666

Polycyclic aromatic hydrocarbons (PAHs) were analyzed in 70 soils distributed in mountain areas such as Montseny (300?C1,700 m), Pyrenees (1,500?C2,900 m), Alps (1,100?C2,500 m), and Tatras (1,400?C1,960 m). Average total PAH concentrations, excluding retene and perylene, were about 400 ng/g in the Pyrenees and 1,300?C1,600 ng/g in the other mountain ranges. No correlations between PAH concentrations and total organic carbon were observed. Retene was the major PAH in the Pyrenean soils of lower altitude. No altitudinal dependence was found between soil PAH concentrations and elevation for the whole dataset. However, in the Tatra soils a statistically significant correlation with altitude was observed involving higher concentrations at higher altitude. This correlation was due to the statistically significant altitudinal dependence of the more volatile PAHs. Another observed altitudinal trend concerned the benz[a]anthracene/(benz[a]anthracene + chrysene + triphenylene) and the benzo[a]pyrene/(benzo[a]pyrene + benzo[e]pyrene) ratios that exhibited a decrease in the more chemically labile compounds, benz[a]anthracene and benzo[a]pyrene, respectively, in the soils located at higher altitude. This observation is consistent with the expected higher photooxidation at higher mountain altitude.  相似文献   

Effects of Vegetation Removal and Urea Application on Iron and Nitrogen Redox Chemistry in Riparian Forested Soils     

Junu Shrestha  Jean Christophe Clément  Joan G. Ehrenfeld  Peter R. Jaffe 《Water, air, and soil pollution》2011,220(1-4):213-223

Riparian wetlands are subject to nitrogen enrichment from upgradient agricultural and urban land uses and also from flooding by nitrogen-enriched surface waters. The effects of this N enrichment on wetland soil biogeochemistry may be mediated by both the presence of plants and the presence of redox-active compounds, specifically iron oxides in the soil. Despite the extensive research on wetland N cycling, the relative importance of these two factors on nitrogen is poorly known, especially for forested wetlands. This study evaluates the responses of the N and the Fe cycles to N enrichment in a riparian forested wetland, contrasting vegetated field plots with plots where the vegetation was removed to test the role of plants. Furthermore, in vitro anaerobic incubations of the experimental soils were performed to track Fe chemical changes over time under anoxic or flooded conditions. Wetland soils treated with N in form of urea, as expected, had significantly higher amounts inorganic nitrogen. In the soils where vegetation was also removed, in addition to inorganic nitrogen pool, increase in organic nitrogen pool was also observed. The results demonstrate the role of vegetation in limiting the effects excess urea has on different soil nitrogen pools. Results from anaerobic incubation of the experimental soils demonstrated the effects of N enrichment on the wetland Fe cycle. The effects of excess nitrogen and the role of vegetation on the Fe cycle in riparian wetland soil became more evident during anaerobic incubation experiments. At the end of the field experiment, Fe concentrations in the soils under the treatments were not significantly different from the control soils at the 5% confidence level. However, during the anaerobic incubation experiment of soils collected at the end of the experiment from these plots, the N-enriched soils and the unvegetated soils maintained significantly elevated concentrations of reducible Fe(III) for the initial 2-week period of incubation, and the soils collected from the plots with both the treatments had the highest Fe(III) concentrations. After 20 days of incubation, however, the Fe(III) concentrations decreased to the similar concentrations in all the incubated soils. The study clarifies the roles vegetation play in mediating the effects of N enrichment and also demonstrates that N enrichment does affect wetland redox cycle, which has strong implications on ecosystem services such as water quality improvement.  相似文献   

Variability in sensory attributes in common bean (Phaseolus vulgaris L.): a first survey in the Iberian secondary diversity center     

Ana Rivera  Daniel Fenero  Antoni Almirall  Juan José Ferreira  Joan Simó  Marçal Plans  Roser Romero del Castillo  Francesc Casañas 《Genetic Resources and Crop Evolution》2013,60(6):1885-1898

Few studies have explored sensory variability in beans. We used geographic, agronomic, morphological, and genetic criteria to select numerous groups of landraces from among the many collected in Catalonia (northeast Spain). Beans cultivated in a single location to avoid environmental effects were submitted to a trained panel for sensory analysis. We used multiple linear regression to explore whether the flavor and texture of the seed (evaluable only by tasting after cooking) can be estimated from easily measurable traits like the appearance of the beans. The degree of variability found for all sensory traits (coefficients of variation: 20–70 %) was similar to that of agronomic traits; however, entries were grouped differently for sensory and agronomic traits, suggesting independent evolution. Negative genotypic correlations between some sensory traits will probably hinder attempts to achieve ideotypes combining low seed-coat perceptibility, low mealiness, and high flavor. Regressions between easily measurable traits (agronomic and culinary traits and appearance of the seeds) and flavor and texture yielded R² values ranging from 0.47 to 0.64. We consider these values good enough for rough screening of sensory attributes in genetic resources studies or breeding.  相似文献   

Factors involved in alleviating water stress by partial crop removal in pear trees     

Marsal J  Mata M  Arbones A  Del Campo J  Girona J  Lopez G 《Tree physiology》2008,28(9):1375-1382

We studied the relief of water stress associated with fruit thinning in pear (Pyrus communis L.) trees during drought to determine what mechanisms, other than stomatal adjustment, were involved. Combinations of control irrigation (equal to crop water use less effective rainfall) and deficit irrigation (equal to 20% of control irrigation), fruit load (unthinned and thinned to 40 fruits per tree) and root pruning (pruned and unpruned) treatments were applied to pear (cv. 'Conference') trees during Stage II of fruit development. Daily patterns of midday stem water potential (Psi(stem)) and leaf conductance to water vapor (g(l)) of deficit-irrigated trees differed after fruit thinning. In response to fruit thinning, gl progressively declined with water stress until 30 days after fruit thinning and then leveled off, whereas the effects of decreased fruit load on Psi(stem) peaked 30-40 days after fruit thinning and then tended to decline. Soil water depletion was significantly correlated with fruit load during drought. Our results indicate that stomatal adjustment and the resulting soil water conservation were the factors determining the Psi(stem) response to fruit thinning. However, these factors could not explain differences in daily patterns between g(l) and Psi(stem) after fruit thinning. In all cases, effects of root pruning treatments on Psi(stem) in deficit-irrigated trees were transitory (Psi(stem) recovered from root pruning in less than 30 days), but the recovery of Psi(stem) after root pruning was faster in trees with low fruit loads. This behavior is compatible with the concept that the water balance (reflected by Psi(stem) values) was better in trees with low fruit loads compared with unthinned trees, perhaps because more carbon was available for root growth. Thus, a root growth component is hypothesized as a mechanism to explain the bimodal Psi(stem) response to fruit thinning during drought.  相似文献   

Response of winter root starch concentration to severe water stress and fruit load and its subsequent effects on early peach fruit development   总被引：1，自引：0，他引：1  

Lopez G  Girona J  Marsal J 《Tree physiology》2007,27(11):1619-1626

Effect of water stress during stage III of peach fruit development on winter root starch concentration (RSC) and subsequent reproductive development was studied. Two irrigation treatments were applied in two consecutive seasons (2003-2004): full irrigation (FI) and no irrigation during stage III of fruit development until visible leaf wilting (LWI), which occurred when midday stem water potential reached -1.80 MPa. Three fruit thinning intensities were applied within each irrigation treatment. The year 2005 was a recovery year in which all trees received full irrigation and commercial fruit thinning. Water deficit and high fruit loads in the previous season significantly reduced the concentration of winter RSC. Fruit set and fruit growth from full bloom to 30 days after full bloom (30 DAFB) increased with increasing winter RSC before other factors, such as inter-fruit competition and availability of carbon from current photosynthesis, came into play. Consequently, severe water stress reduced the total number of fruits and fruit dry mass growth 30 DAFB. However, during the recovery year and after fruit thinning, fruit loads were similar between irrigation treatments and yield capacity remained unaffected. Peach fruit production recovered quickly from the deleterious effects of two consecutive years of water stress because of a combination of two factors: (1) reduced initial fruit set that was still adequate to achieve a commercial crop; and (2) the low sensitivity of fruit growth 30 DAFB to winter RSC.  相似文献   

Hypovirulent effect of the Cryphonectria hypovirus 1 in British isolates of Cryphonectria parasitica     

Pedro Romon‐Ochoa  Caroline Gorton  Alex Lewis  Sietse van der Linde  Joan Webber  Ana Prez‐Sierra 《Pest management science》2020,76(4):1333-1343

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Effect of allele combinations at Ppd-1 loci on durum wheat grain filling at contrasting latitudes     

Jose M. Arjona  Conxita Royo  Susanne Dreisigacker  Karim Ammar  Joan Subirà  Dolors Villegas 《Journal of Agronomy and Crop Science》2020,206(1):64-75

Flowering time is the most critical developmental stage in wheat, as it determines environmental conditions during grain filling. Thirty-five spring durum genotypes carrying all known allele variants at Ppd-1 loci were evaluated in fully irrigated field experiments for three years at latitudes of 41°N (Spain), 27°N (northern Mexico) and 19°N (southern Mexico). Relationships between weight of central grains of main spikes (W) and thermal time from flowering to maturity were described by a logistic equation. Differences in flowering time between the allele combination causing the earliest (GS100/Ppd-B1a) and the latest (Ppd-A1b/Ppd-B1a) flowering were 7, 20 and 18 days in Spain, northern Mexico and southern Mexico, respectively. Flowering delay drastically reduced the mean grain filling rate (R) and W at all sites. At autumn-sowing sites, an increase of 1°C in mean temperature during the first half of the grain filling period decreased W by 5.2 mg per grain. At these sites, W was strongly dependent on R. At the spring-sowing site (southern Mexico), W depended on both R and grain filling duration. Our results suggest that incorporating the allele combinations GS100/Ppd-B1a and GS105/Ppd-B1a (alleles conferring photoperiod insensitivity) in newly released varieties can reduce the negative effects of climate change on grain filling at the studied latitudes.  相似文献   

Contrasting time-scale effects of land-use legacy on species richness,diversity and composition in Mediterranean scrubland communities     

Gamboa-Badilla  Nancy  Segura  Alfonso  Bagaria  Guillem  Basnou  Corina  Pino  Joan 《Landscape Ecology》2020,35(12):2745-2757

Context

It is known that land-use and land-cover (LULC) changes affect plant community assembly for decades. However, both the short- and the long-term effects of contrasting LULC change pathways on this assembly are seldom explored.

Objectives

To assess how LULC change pathways affect woody plant community parameters (i.e. species richness, diversity and evenness) and species’ presence and abundance, compared with environmental factors and neutral processes.

Methods

The study was performed in Mediterranean limestone scrublands in NE Spain. Cover of each woody species was recorded in 150 scrubland plots belonging to five LULC change pathways along the past century, identified using land-cover maps and fieldwork. For each plot, total woody and herbaceous vegetation cover, local environmental variables and geographical position were recorded. Effects of these pathways and factors on plant community parameters and on species presence and abundance were assessed, considering spatial effects potentially associated to neutral processes.

Results

Species richness and diversity were associated with LULC change pathways and elevation, while evenness was only associated with this last. Pathways and environmental variables explained similar variance in both species’ presence and cover. In general, while community parameters were affected by recent-past (1956) use, species presence and abundance were associated with far-past (pre-1900) cropping. No relevant spatial effect was detected for any studied factor.

Conclusions

Historical LULC changes and current environmental factors drive local-scale community assembly in Mediterranean scrublands to an equal extent, while contrasting time-scale effects are found at community and species level. Neutral, dispersal-based processes are found to be non-relevant.

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Assessing wild bees in perennial bioenergy landscapes: effects of bioenergy crop composition,landscape configuration,and bioenergy crop area     

John B. Graham  Joan I. Nassauer  William S. Currie  Herbert Ssegane  M. Cristina Negri 《Landscape Ecology》2017,32(5):1023-1037

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