Long-term studies on ground management in rainfed olive orchards

Two decades of research on soil management in rainfed olive graves, encompassing four experimental ftelds, one of which took eighteen years of continuous assessment, allowed comparative evaluation of severa! treatments including conventional tillage, residual herbicides, post-emergence herbicides, covers of natural vegetation (fertilized and unfertilized), sown covers managed as green manures and incorporated into the soil, or shredded and kept in the ground as a mulch, and sown covers of self-reseeding pasture legumes. This series of studies allowed showing that a better contrai of the herbaceous vegetation improves olive growth and yield and a greater development of the herbaceous vegetation improves severa! indicators of the soil fertility, which creates a great ambiguity. However, a large set of advantages comes from the use of early-season self-reseeding annual legumes. These plants presenta very short growing cycle and develop asynchronously with the trees (in winter, during the resting period of olive), showing reduced competition for water, allowing high productivity even in rainfed conditions. Additionally, they protect the soil from erosion ali year round, with live vegetation during winter anda mulch of dead vegetation during the summer, improve soil fertility, including the increase of soil organic matter, and are able to ftx nitrogen improving the nitrogen nutritional state of the trees.info:eu-repo/semantics/publishedVersio

A Two-Step Segmentation Method for Breast Ultrasound Masses Based on Multi-resolution Analysis

Breast ultrasound images have several attractive properties that make them an interesting tool in breast cancer detection. However, their intrinsic high noise rate and low contrast turn mass detection and segmentation into a challenging task. In this article, a fully automated two-stage breast mass segmentation approach is proposed. In the initial stage, ultrasound images are segmented using support vector machine or discriminant analysis pixel classification with a multiresolution pixel descriptor. The features are extracted using non-linear diffusion, bandpass filtering and scale-variant mean curvature measures. A set of heuristic rules complement the initial segmentation stage, selecting the region of interest in a fully automated manner. In the second segmentation stage, refined segmentation of the area retrieved in the first stage is attempted, using two different techniques. The AdaBoost algorithm uses a descriptor based on scale-variant curvature measures and non-linear diffusion of the original image at lower scales, to improve the spatial accuracy of the ROI. Active contours use the segmentation results from the first stage as initial contours. Results for both proposed segmentation paths were promising, with normalized Dice similarity coefficients of 0.824 for AdaBoost and 0.813 for active contours. Recall rates were 79.6% for AdaBoost and 77.8% for active contours, whereas the precision rate was 89.3% for both methods.info:eu-repo/semantics/publishedVersio

Olive response to potassium applications under different water regimes and cultivars

Although potassium (K) is a macronutrient few studies have evaluated the response of olive tree to K fertilization. In this work results of two field and two pot K fertilizer experiments are presented. One of the field trials was conducted in a commercial young olive grove. The second was conducted in a plantation purposely established for this study. In the two fieldand thefirst potexperiment,theK supply was the single variation factor. The second pot experiment was arranged as a factorial with two K rates, two water regimes and two cultivars (‘Arbequina’ and ‘Cobranc¸osa’). K supply did not increase olive tree growth or yield. Accumulated olive yield in the first field experiment, for instance, varied from 2.46 and 2.84 kg tree-1, respectively in K treated and untreated plants. K supply increased the shoot/root ratio (1.6–2.0 from the control to the most fertilized treatment) and the concentration of K in roots (2.9–11.2 g kg-1) to a greater extent than in leaves (7.0–11.9 g kg-1), suggesting that shoots are a priority sink for K and roots may store the nutrient as a reserve. Plant water status and chlorophyll a fluorescence were not significantly affected by K applications. Plants suffering from water stress yielded less phytomass (40.2–56.4 g pot-1, respectively in control and well-watered plants) and showed higher K concentrations in leaves (14.2–11.6 g kg-1) and lower in roots (4.9–6.8 g kg-1) which is probably due to the reduction of K uptake from the dry soil. ‘Cobranc¸osa’ appeared to be more tolerant to water stress than ‘Arbequina’. These experiments showed a poor response of olive tree to K fertilization. Considering that K is usually applied by farmers every year, it seems that further studies on K fertilizationin olive are needed in order to adjust K fertilizer rates to crop needs.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Programme PT2020 for financial support to CIMO (UID/AGR/00690/2013). The work was also funded by the INTERACT Project—‘‘Integrative Research in Environment, Agro-Chains and Technology’’, No. NORTE- 01-0145-FEDER-000017, in its line of research entitled ISAC, co-financed by the European Regional Development Fund (ERDF) through NORTE 2020 (North Regional Operational Program 2014/2020). For authors integrated in the CITAB research centre, it was further financed by the FEDER/ COMPETE/POCI—Operational Competitiveness and Internationalization Programme, under Project POCI-01-0145- FEDER-006958, and by National Funds of FCT–Portuguese Foundation for Science and Technology, under the Project UID/ AGR/04033/2013.info:eu-repo/semantics/publishedVersio

Olive tree response to applied phosphorus in field and pot experiments

Phosphorus (P) application in olive orchards is very common in the Mediterranean basin although experimental evidence of crop response to applied P is practically non-existent. In this work soil P and tree P nutritional status of the olive groves of NE Portugal were assessed from a population of 1808 soil and 2252 leaf samples. Plant response to applied P was evaluated from two field and two pot experiments carried out with the cultivar ‘Cobrançosa’. The analyses of soil and leaf samples of the olive orchards of the region indicate that P fertilizer recommendations should be based on leaf rather than on soil analyzes, since the latter seems to overestimate the need for P. The field and pot experiments hardly showed any positive response to P applications, which is a sign that the use of P fertilizer in olive can be substantially reduced. Nonetheless, in one pot experiment, P application significantly increased total dry matter yield during three consecutive years, in a strict association with higher tissue P concentrations and enhanced photosynthetic activity, as revealed by gas exchange and chlorophyll fluorescence traits. The experimental results also showed that the roots can uptake and store P when available in the soil, which may buffer the levels of P in the shoots. The acid phosphate activity can provide useful information but deserves caution in the interpretation of results since it depends not only on the availability of inorganic P in the soil, but also on the available organic substrate and pH.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Programme PT2020 for financial support to CIMO (UID/AGR/00690/2013). The work was also funded by the INTERACT project – “Integrative Research in Environment, Agro-Chains and Technology”, no. NORTE-01-0145- FEDER-000017, in its line of research entitled ISAC, co-financed by the European Regional Development Fund (ERDF) through NORTE 2020 (North Regional Operational Program 2014/2020). For authors integrated in the CITAB research centre, it was further financed by the FEDER/COMPETE/POCI – Operational Competitiveness and Internationalization Programme, under Project POCI-01-0145-FEDER- 006958, and by National Funds of FCT–Portuguese Foundation for Science and Technology, under the project UID/AGR/04033/2013.info:eu-repo/semantics/publishedVersio

The effect of nitrogen applications on the growth of young olive trees and nitrogen efficiency

Two field trials (FieldExp1 and FieldExp2) and a pot experiment (PotExp) were c0onducted over a period of 3 years to assess olive tree response to nitrogen (N) applications and to estimate apparent N recovery. FieldExp1 was installed in a 3-year-old olive grove. FieldExp2 consisted of a plantation of young rooted plants. Two treatments were applied in both experiments: N application and a nonfertilized control. In PotExp, 4 N rates were used. In FieldExp1, olive yield significantly increased with applied N in only 1 of the 3 growing seasons. In FieldExp2, aboveground dry matter yield significantly increased with N application. In PotExp, total dry matter yield displayed a typical saturation curve in response to N rates. The poor response of olive yield to N application might be due to the reduced amount of N removed in the crop, and also to the negative interaction found between N application and water deficit. Apparent N recovery reached values varying from 13.1% in FieldExp2 to ~100% in PotExp. The results indicate that the olive response to N and N use efficiency seem to be influenced more by the agroecological conditions defining target yield and N loss, rather than by plant species.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) and FEDER under Program PT2020 for financial support to CIMO (UID/AGR/00690/2013). The work was also funded by the INTERACT project “Integrative Research in Environment, Agro-Chains and Technology”, no. NORTE-01-0145- FEDER-000017, in its line of research entitled ISAC, cofinanced by the European Regional Development Fund (ERDF) through NORTE 2020 (North Regional Operational Program 2014/2020).info:eu-repo/semantics/publishedVersio

Liming and application of nitrogen, phosphorus, potassium, and boron on a young plantation of chestnut

European chestnut is the most important cash crop in the highlands of NE Portugal. However, limited data on cropping technique are available to help farmers make decisions. This work is motivated by the lack of data related to chestnut response to fertilizer application. It reports results from a field fertilization trial consisting of the application of a combination of lime (L), nitrogen (N), phosphorus (P), potassium (K), and boron (B), namely LNPKB, NPKB, –NPKB, N–PKB, NP–KB, and NPK–B. Seedlings of chestnut were planted in June 2013 and grown for four growing seasons. Plant height, trunk diameter, and pruning wood were assessed every year and used as indicators of tree crop growth. Elemental leaf analysis and other tools [SPAD-502 chlorophyll meter; Field Scout CM 1000 NDVI (normalized difference vegetation index) meter, and the OS-30p+ fluorometer] were used to assess plant nutritional stresses. In January 2017 soil samples were collected at three depths (0–5, 5–10, and 10–20 cm) to determine several soil fertility parameters. The nonapplication of K and B reduced the tree crop growth and pruning residues. Leaf analysis revealed leaf K and B concentrations respectively in the NP–KB and NPK–B treatments to be in the deficient range previously established for chestnut. SPAD readings and NDVI detected the reduced availability of N associated with the –NPKB treatment but not the reduced plant growth associated with NP–KB or NPK–B treatments. The dark adaptation protocols of FV/FM, FV/F0, and OJIP measurements performed with the OS-30p+ fluorometer failed to diagnose the nutrient stresses detected by leaf analysis or the reduction in plant growth.info:eu-repo/semantics/publishedVersio

Estudos de fertilização em castanheiro com aplicação de calcário, azoto, fósforo, potássio ou boro

Este trabalho foi motivado pela falta de informação disponível sobre resposta do castanheiro à correção do pH e à aplicação de outros fertilizantes ao solo, numa fase em que, face aos bons preços a que se vende a castanha, os produtores têm estado muito predispostos a investir na técnica cultural. O trabalho reporta resultados de um ensaio em castanheiro que decorreu durante quatro anos, onde se ensaiaram seis modalidades de fertilização: aplicação de calcário mais azoto (N), fósforo (P), potássio (K) e boro (B) (CalNPKB); aplicação de N, P, KeB (NPKB); aplicação de P, Ke B (-NPKB); aplicação de N, K e B (N-PKB); aplicação de N, Pe B (NP-KB); e aplicação de N, Pe K (NPK-B). Os tratamentos fertilizantes foram aplicados à instalação das jovens plantas no ano de plantação e mantidos por quatro anos consecutivos, com exceção do calcário que só foi aplicado à instalação. Foi avaliada a resposta das plantas aos tratamentos fertilizantes através da medição da sua altura e do diâmetro do tronco e da lenha de poda produzida, bem como do estado nutricional das plantas avaliado a partir de análises elementares às folhas e com aparelhos portáteis. As plantas dos tratamentos NPK-B, NP-KB e -NPKB revelaram, respetivamente, teores de B, Ke N significativamente mais baixos que os restantes tratamentos. O tratamento N-PKB não revelou teores de P mais baixos que os restantes e o tratamento CalNPKB não revelou teores de cálcio ou magnésio superiores aos restantes. A altura das plantas e o diâmetro dos caules foram significativamente mais baixos nas modalidades NPKB e NP-KB. Os resultados dos aparelhos portáteis de medição da condição das plantas confirmaram que a falta de B e K foram os tratamentos que mais reduziram o estado nutricional das plantas nos respetivos elementos e maior influencia negativa exerceram no crescimento em altura e engrossamento das árvores. Recomenda-se que as futuras recomendações de fertilizaçâo para esta cultura tenha estes dois elementos em conta.info:eu-repo/semantics/publishedVersio

Agronomic practices change the patterns of soil glomalin in olive rainfed orchards

Glomalin, a thermostable hydrophobic glycoprotein produced by arbuscular mycorrhizal fungi, plays an important role in the stability of soil aggregates and in the sequestration of C, N and heavy metals, being their concentrations dependent from agronomic practices such as tillage and application of pesticides and fertilizers. Despite the recognized importance of glomalin in soil quality, studies on olive groves are scarce. The study conducted on summer 2017 in three different rain fed orchards (cv. Cobran~osa) of Northeast Portugal revealed that both total glomalin, measured as Bradford-reactive soil protein (T-BRSP}, and the easily extractable Bradford-reactive soil protein (EE-BRSP) concentrations were lower under mechanical cultivation than on a permanent sward grazed with a flock of sheep or than on an annual legume cover crop. Moreover, higher TBRSP and EE-BRSP levels were found on orchards without phosphorus and boron supply, and also on the top soil layer (0.1 0 cm) and on tree row, mainly in younger orchards. Interestingly, one soil presented a twofold superior EE-BRSP: T- BRSP ratio than the other two soils, representing an increase of labile g lomalin, probably re lated with greater applications of copper formulations to control olive fungal diseases. This study demonstrated that less disruptive agronomic practices influences positivety the levels of glomalin, an appropriate indicator of healthy soil conditions, which in turn may favour carbon sequestration.This work was funded by the INTERACT project - •Integrative Research in Environment, Agro-Chains and Technology': no. NORTE-01-0145-FEDER- 000017, in its lines of research entitled I SAC, eo-financed by the European Regional Development Fund (ERDF) through NORTE 2020 (North Regional Operational Program 2014/2020).info:eu-repo/semantics/publishedVersio

Leguminous cover crop to adapt olive rainfed orchards to climate change

Leguminous cover crops have the potential to contribute to soil protection against erosion and improve carbon sequestration, soil and water quality and might help agricultura! systems become more resilient to climate change. The aim of this study was to investigate the effects of a cover crop of self-reseeding annuallegumes of short growing cycle on physiological and biochemical responses of twenty-six-year-old olive trees (Olea europaea L. cv. Cobrançosa) grown under rainfed conditions, when compared with conventional tillage. The results showed that the leguminous cover crop ameliorates the physiological and biochemical performance of olive tree during the drought season, judging by the rise of net photosynthesis, transpiration rate and stomatal conductance, whereas the opposite pattern was observed for the concentration of total phenols and for total antioxidant activity in leaves. ln addition, it was observed an increase on yield, size and weight of olive fruits. These results indicate that the use of well-designed, locally-tailored cover crop mixtures, associated with an appropriate mowing time, is a very promising strategy to implement in olive orchards under water scarcity. Thus, cover cropping is a win-win strategy as it increases farm benefits and provides ecosystem services.This work was funded by the INTERACT project- "Jntcgrative Research in Environment, Agro-Chains and Technology", no. NORTE-01-0145-FEDER-000017, in its !ines of research entitled ISAC, co-tinanced by the European Regional Devclopment Fund (ERDF) through NORTE 2020 (North Regional Operational Program 20 14/2020). SM (PD/BD/135327/2017), EM (PD/BD/128274/2017) and CB (PD/BD/52543/2014) acknowledge the financ ial support provided by the FCT-Portuguese Foundatíon for Science and Technology, under the Doctoral Programme "Agricultura] Production Chains- from fork to farm" (PD/00122/2012).info:eu-repo/semantics/publishedVersio

Use of kaolin as a summer stress alleviating product in olive orchards under rainfed conditions

In a changing world, where is expected the temperatures rising and the reduction in precipitation in some semi-arid areas of the globe, the search for new agronomic practices that help crops to maintain and/or increase yields and quality is a continuous challenge. Kaolin (KL) exogenous application has been considered a short-term solution to alleviate the adverse effects of summer stress. The formed particle film increases the reflection of excess radiation reducing the risk of leaf damage from heat load accumulation and solar injury. Olive trees (Olea europaea L.) cultivated under rainfed conditions were sprayed with KL (5%) during two consecutive years in the beginning of the summer season. In general, relatively to the control group, KL-sprayed plants showed an enhancement in leaf water status, stomatal conductance and photosynthetic capacity and a reduction in leaf sclerophylly. In the severest period analyzed, at the end of the second-year summer, KL has lost the effectiveness of keeping gas exchange above the control measurements. However, in both years, allowed a faster restauration of the physiological functions in early autumn and contributed to higher crop yield. Overall, the results of the present investigation revealed that KL were effective in preventing the adverse effects of summer stress on crop performance and yield.Doctoral fellowship under the Doctoral Program “Agricultural Production Chains – from fork to farm” (PD/00122/2012) provided by the FCT-Portuguese Foundation for Science and Technology to C. Brito (PD/BD/52543/2014). Institution CITAB, for its financial support through the European Investment Funds by FEDER/COMPETE/POCI– Operational Competitiveness and Internationalization Program, under Project POCI-01-0145-FEDER-006958 and National Funds by FCT - Portuguese Foundation for Science and Technology, under the project UID/AGR/04033/2013.info:eu-repo/semantics/publishedVersio