1,720,984 research outputs found
Comparison between two methods of estimation of chilling and heat requirements for flowering in almond
No full textA precise determination of thermic requirements (chilling and heat) for breaking dormancy is quite difficult under field conditions. However, quantification under laboratory conditions should be considered with caution and it is costly and time consuming when analyzing a large number of genotypes. For this reason, statistical models based on the analysis of historical blooming dates have been developed to fit the responses of tree species to local weather conditions. Chilling and heat requirements for breaking dormancy and flowering were studied in five local almond cultivars with a widespread time of full bloom (‘Pizzuta d’Avola’, the earliest, ‘Tribuzio’, ‘Tuono’, ‘Cristomorto’ and ‘Rana Gentile’, the latest) in Apulia region (southern Italy). The chilling portions (CP), determined by dynamic model, and the growing degree hours by Richardson model (GDH) were used to determine chilling and heat accumulations, respectively. Using both full bloom dates and temperatures of previous seasons for nine years, two methods for estimating thermic requirements were compared: the Ashcroft method (AM), and a new version (Ashcroft method modified, AMM) that takes into account in a higher extent the GDH accumulation in comparison with AM, and allows selecting the optimal requirements when alternative choices are possible. The two methods generally underestimated the blooming date, but with a difference from the real one within 5 days for most of the cases studied. AMM resulted more effective than the original method in Apulian semi-arid conditions. The estimation of thermic requirements using temperature data and full bloom dates seemed to be useful, easy and not too expensive to be implemented for a wide number of cultivars
Sustainable agriculture and soil conservation
Full text linkSoil degradation is one of the most topical environmental threats. A number of processes causing soil degradation, specifically erosion, compaction, salinization, pollution, and loss of both organic matter and soil biodiversity, are also strictly connected to agricultural activity and its intensification. The development and adoption of sustainable agronomic practices able to preserve and enhance the physical, chemical, and biological properties of soils and improve agroecosystem functions is a challenge for both scientists and farmers. This Special Issue collects 12 original contributions addressing the state of the art of sustainable agriculture and soil conservation. The papers cover a wide range of topics, including organic agriculture, soil amendment and soil organic carbon (SOC) management, the impact of SOC on soil water repellency, the effects of soil tillage on the quantity of SOC associated with several fractions of soil particles and depth, and SOC prediction, using visible and near-infrared spectra and multivariate modeling. Moreover, the effects of some soil contaminants (e.g., crude oil, tungsten, copper, and polycyclic aromatic hydrocarbons) are discussed or reviewed in light of the recent literature. The collection of the manuscripts presented in this Special Issue provides a relevant knowledge contribution for improving our understanding on sustainable agriculture and soil conservation, thus stimulating new views on this main topic
The use of a nutrient quality score is effective to assess the overall nutritional value of three brassica microgreens
Get PDFMicrogreens have immense potential for improving dietary patterns, but little information is available regarding their overall nutritional value. We evaluated the nutritional traits of three hydroponically grown Brassica microgreens by using a Nutrient Quality Score. Micro cauliflower, micro broccoli and micro broccoli raab were grown using nutrient solutions with three different NH4:NO3 molar ratios (5:95, 15:85, and 25:75). Protein, dietary fiber, β-carotene, α-tocopherol and mineral elements (Ca, K, Mg, Fe, Zn, Cu, Mn, and Na) were analyzed. We developed the Nutrient Quality Score (NQS 11.1) on the basis of 11 desirable nutrients and 1 nutrient (sodium) to be limited. All Brassica microgreens are an excellent source of Vitamins A and E (more than 20% of the daily reference value-DRV), as well as a good source of calcium and manganese (10-19% of the DRV). Micro cauliflower showed a NQS 11.1 at 47% higher than micro broccoli raab and micro broccoli. Using NH4:NO3 25:75 molar ratio, the average score was 27% higher than other molar ratios. In all cases, the microgreens in the present study showed a higher NQS 11.1 than their mature counterpart (on the basis of data from the United States Department of Agriculture), highlighting that the score of micro cauliflower was about six-fold higher than mature cauliflower. In conclusion, the NQS 11.1 was useful for assessing the overall nutritional quality of the three Brassica microgreens, instead of simply quantifying nutrient content, in order to compare a single nutrient among different genotypes. Furthermore, the results highlight that the micro broccoli raab, micro broccoli and micro cauliflower in this study can be considered nutrient-rich vegetables that are able to improve dietary patterns more effectively than their mature counterparts
The mechanical impact of water affected the soil physical quality of a loam soil under minimum tillage and no-tillage: An assessment using beerkan multi-height runs and BEST-procedure
Full text linkThe multi-height (low, L = 3 cm; intermediate, M = 100 cm; high, H = 200 cm) Beerkan run methodology was applied on both a minimum tilled (MT) (i.e., up to a depth of 30 cm) and a no-tilled (NT) bare loam soil, and the soil water retention curve was estimated by the BEST-steady algorithm. Three indicators of soil physical quality (SPQ), i.e., macroporosity (Pmac), air capacity (AC) and relative field capacity (RFC) were calculated to assess the impact of water pouring height under alternative soil management practices. Results showed that, compared to the reference low run,Mand H runs affected both the estimated soil water retention curves and derived SPQ indicators. Generally, M-H runs significantly reduced the mean values of Pmac and AC and increased RFC for both MT and NT soil management practices. According to the guidelines for assessment of SPQ, the M and H runs: (i) worsened Pmac classification of both MT and NT soils; (ii) did not worsen AC classification, regardless of soil management parameters; (iii) worsened RFC classification of only NT soil, as a consequence of insufficient soil aeration. For both soil management techniques, a strong negative correlation was found between the Pmac and AC values and the gravitational potential energy, Ep, of the water used for the infiltration runs. A positive correlation was detected between RFC and Ep. The relationships were plausible from a soil physics point of view. NT soil has proven to be more resilient than MT. This study contributes toward testing simple and robust methods capable of quantifying soil degradation effects, due to intense rainfall events, under different soil management practices in the Mediterranean environment
Physiological responses of apricot and peach cultivars under progressive water shortage: Different crop signals for anisohydric and isohydric behaviours
Full text linkThe knowledge about the behaviour of different fruit tree species when subjected to water shortage is pivotal to pair correctly the species with the environment, as well as to choose the most reliable index for monitoring the plant water status. Net photosynthesis (Pn) and stomatal conductance (gs) are considered some of the most reliable variables describing the plant water status, functionality and potential productivity, but their measurement are actually time consuming, complex and expensive. The aims of the present study were to investigate the effect of a progressive water stress on leaf functioning and plant water status of two stone fruit trees species; to study the water relations within the Soil-Plant-Atmosphere Continuum; to assess a pool of indices for estimating Pn and gs by means of other variables quick to be measured, potentially through less expensive and user-friendly sensors. The trial was carried out on an early ripening apricot variety (Prunus armeniaca L. cv. Primius) and on a late ripening peach variety (Prunus persica (L.) Batsch cv. Calred) subjected to progressive dry down. Trees were monitored for stem water potential, leaf temperature, chlorophyl fluorescence, Pn and gs. “Primius” and “Calred” behaved as near anisohydric and near-isohydric plants, respectively. In “Primius” Pn and gs were more affected by soil water content than vapour pressure deficit (VPD) and the opposite occurred in “Calred”, suggesting a different approach to be used for managing water in the two cultivars. Chlorophyll fluorescence variables and leaf to air temperature difference (ΔT), combined properly by means of stepwise multiple regression analysis approach, were selected as good predictors of Pn for both the species. ΔT and VPD were selected to estimate gs, using the same approach. The prediction performance of the models resulted good suggesting their possible use for driving irrigation in a more sustainable and plant-based way
Estimating the soil hydraulic functions of some olive orchards: Soil management implications for water saving in soils of salento peninsula (Southern Italy)
Full text linkSaving water resources in agriculture is a topic of current research in Mediterranean environments, and rational soil management can allow such purposes. The Beerkan Estimation of Soil Transfer parameters (BEST) procedure was applied in five olive orchards of Salento peninsula (southern Italy) to estimate the soil physical and hydraulic properties under alternative soil management (i.e., no-tillage (NT) and minimum tillage (MT)), and to quantify the impact of soil management on soil water conservation. Results highlighted the soundness of BEST predictions since they provided consistent results in terms of soil functions or capacitive-based soil indicators when (i) the entire data set was grouped by homogeneous classes of texture, bulk density, and capillarity of the soil, (ii) the predictions were compared with the corresponding water retention measures independently obtained in lab, and (iii) some correlations of literature were checked. BEST was applied to establish a comparison at Neviano (NE) and Sternatia (ST) sites. The two neighboring NT soils compared at NE showed substantial discrepancies in soil texture (i.e., sandy loam (NE-SL) or clay (NE-C)). This marked difference in soil texture could determine a worsening of the relative field capacity at the NE-SL site (relative field capacity, RFC < 0.6), as compared to NE-C where RFC was optimal. The current soil management determined a similar effect (RFC < 0.6) at Sternatia (ST-MT vs. ST-NT), but the worsening in soil properties, due to soil tillage, must be considered substantially transient, as progressive improvement is expected with the restoration of the soil structure. The results of this work suggest that strategic MT can be a viable solution to manage the soil of Salento olive orchards
Maize Yield Response, Root Distribution and Soil Desiccation Crack Features as Affected by Row Spacing
Full text linkPlant density is among the most critical factors affecting plant yields and resource use efficiency since it drives the exploitation of the available resources per unit area, root distribution and soil water losses by direct evaporation from the soil. Consequently, in fine-textured soils, it can also affect the formation and development of desiccation cracks. The aim of this study, carried out on a sandy clay loam soil in a typical Mediterranean environment, was to investigate the effects of different row spacings of maize (Zea mais L.) on yield response, root distribution and the main features of desiccation cracks. The field experiment compared bare soil and soil cropped with maize using three plant densities (6, 4 and 3 plants m−2), obtained by keeping the number of plants in a row constant and varying the distance between the rows (0.5–0.75–1.0 m). The highest kernel yield (16.57 Mg ha−1) was obtained with the greatest planting density (6 plants m−2) with a row spacing of 0.5 m; significantly lower yields were recorded with spacings of 0.75 and 1 m, with a decrease of 8.09% and 18.24%, respectively. At the end of the growing season, soil moisture in the bare soil was on average 4% greater in comparison to the cropped soil and was also affected by row spacing, decreasing with the decrease in the inter-row distance. An inverse behaviour was observed between soil moisture and both root density and desiccation crack size. Root density decreased to the increase in soil depth and to the increase in distance from the row. The pluviometric regime occurred during the growing season (total rainfall of 343 mm)-resulted in the formation of cracks of reduced size and with an isotropic behaviour in the bare soil, whereas in the cultivated soil, the cracks were parallel to the maize rows and increased in size with decreasing inter-row distance. The total volume of the soil cracks reached a value of 135.65 m3 ha−1 in the soil cropped with a row distance of 0.5 m, and was about ten times greater in comparison to the bare soil and three times greater in comparison to a row spacing of 1 m. Such a volume would allow a recharge of 14 mm in the case of intense rainy events on soil characterised by low permeability
Assessment of soil quality under different soil management strategies: Combined use of statistical approaches to select the most informative soil physico-chemical indicators
No full textAssessment of soil quality under different management practices is crucial for sustainable agricultural production and natural resource use. In this study, different statistical methods (principal component analysis, PCA; stepwise discriminant analysis, SDA; partial least squares regression with VIP statistics, PLSR) were applied to identify the variables that most discriminated soil status under minimum tillage and no-tillage. Data collected in 2015 from a long-term field experiment on durum wheat (Triticum durum Desf.) were used and twenty soil indicators (chemical, physical and biological) were quantified for the upper soil layer (0–0.20 m). The long-term iteration of different management strategies affected soil quality, showing greater bulk density, relative field capacity (RFC), organic and extractable carbon contents (TOC and TEC) and exchangeable potassium under no-tillage. PCA and SDA confirmed these results and underlined also the role of available phosphorous and organic carbon fractions as variables that most discriminated the treatments investigated. PLSR, including information on plant response (grain yield and protein content), selected, as the most important variables, plant nutrients, soil physical quality indicators, pH and exchangeable cations. The research showed the effectiveness of combining variable selection methods to summarize information deriving from multivariate datasets and improving the understanding of the system investigated. The statistical approaches compared provided different results in terms of variables selected and the ranking of the selected variables. The combined use of the three methods allowed the selection of a smaller number of variables (TOC, TEC, Olsen P, water extractable nitrogen, RFC, macroporosity, air capacity), which were able to provide a clear discrimination between the treatments compared, as shown by the PCA carried out on the reduced dataset. The presence of a response variable in PLSR considerably drove the feature selection process
Different Suitability of Olive Cultivars Resistant to Xylella fastidiosa to the Super-Intensive Planting System
No full textUntil today, only Leccino and Fs-17 (=Favolosa®) olive cultivars proved resistant to Xylella fastidiosa subsp. pauca (Xfp) due to a low presence of bacteria in the xylem. Integrated disease management in olive growing areas threatened by the spread of Xfp is crucial to overcoming the environmental, economic and social crisis. Since the EU Decision allows for the plantation of resistant olive cultivars in infected areas, there is a need to define a suitable plantation system for these cultivars. The adoption of new planting systems, such as intensive and super-intensive (SHD), could compensate for the economic losses and restore the olive agroecosystem. The aim is to ascertain the suitability of the available Xfp-resistant cultivars to SHD planting systems that demonstrate the best economic and environmental sustainability. Hence, a five-year study was established in an experimental SHD olive orchard (Southern Italy) in order to analyse the main vegetative and productive traits of Leccino and Fs-17, together with four other Italian cultivars (Cipressino, Coratina, Frantoio and Urano), compared with the well-adapted cultivars to SHD orchards (Arbequina and Arbosana), by means of the von Bertalanffy function. The results indicated that cv. Fs-17 showed sufficient suitability for SHD planting systems, giving the best-accumulated yield despite some canopy growth limitations, whereas cv. Leccino did not show satisfactory results in terms of both vegetative and yield parameters, confirming its suitability for intensive planting systems. These results are useful for optimizing integrated resistance management in Xfp-infected areas by planting resistant host plants
Heavy metal concentrations in a soil irrigated with treated municipal wastewater: use of mixed models to analyze the effect over time
No full textIn arid and semi-arid regions of the world, non-conventional waters may represent an important complementary irrigation source. To investigate potential soil contaminations risks, repeated measurement experiments and rigorous methodological approaches may be adopted to assess variations of contaminant concentrations in the soil, eliminating possible confounding effects due to correlations over time. A field trial was carried out in Southern Italy to assess variation of heavy metals concentrations in a soil irrigated with: (i) freshwater (FW), (ii) a secondary-treated (SW) and (iii) a tertiary-treated municipal effluent (TW).
Concentrations of cadmium, chromium, copper, nickel, lead and zinc were quantified by ICP-OES on soil samples collected over three sampling dates. Mixed effects models accounting for residual autocorrelation were used to evaluate differences over time and treatments and the following variance-covariance structures were compared: compound symmetry (CS); autoregressive of first order (AR(1)); autoregressive of first order with heterogeneous variances (ARH(1)). ARH(1) models were significant in most of the cases investigated, confirming heterogeneity of variances observed over time. At the end of each irrigation season, soil heavy metal contents did not show significant differences among treatments. Significant interactions between water source and sampling time were observed mainly under SW and TW supply; in any case no increase of metals over time was recorded.
Our results confirmed low risk of soil metals contamination after short and medium term irrigation with treated municipal wastewater. However, when using non-conventional water resources, proper irrigation management and continuous monitoring of water and soil are needed to avoid soil degradation
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