O olival é uma das culturas amplamente distribuídas na região mediterrânica e com grande impacto em Portugal, nomeadamente na região de Trás-os-Montes onde apresenta elevada importância socioeconómica. Sendo a oliveira uma espécie muito exigente em boro e apresentado este micronutriente importantes funções nas plantas, entre as quais na estrutura da parede celular, divisão celular, integridade das membranas, transporte de açúcares e metabolismo dos hidratos de carbono, relações hídricas, floração, frutificaçâo e regulação hormonal, torna-se necessário aprofundar os conhecimentos sobre a resposta da oliveira à fertilizaçâo com boro. O presente estudo foi realizado num olival (cv. Cobrançosa) de sequeiro localizado em Bragança, tendo sido avaliados dois níveis de boro: 3 kg/ha e ausência de boro. Durante o stresse estivai foram avaliados parâmetros de trocas gasosas e fluorescência da clorofila o, conteúdo relativo em água, concentração de pigmentos fotossintéticos e indicadores de crescimento. Verificou-se que as plantas fertilizadas com boro apresentaram maior conteúdo relativo em água, condutância estomática, taxa de transporte de eletrões, quenching fotoquímico e concentração de ciorofilas, conduzindo a incrementos da taxa de fotossíntese líquida e do crescimento, expressa pelo diâmetro do tronco e pelo volume da copa. Estes resultados demonstram que a adição de boro melhora a fisiologia da oliveira em regime de sequeiro, fornecendo nova informação que poderá ajudar a aperfeiçoar as recomendações de fertilizaçâo para a cultura.

A oliveira [Olea europaea L.) é uma espécie que frequentemente se encontra sujeita a longos períodos de seca e altas temperaturas, o que afeta a sua atividade fisiológica e, consequentemente, a sua produtividade. A glicina betaína é um importante soluto orgânico que apresenta um papel crucial na tolerância das plantas a alguns tipos de stresse/ incluindo o défice hídrico, por estar envolvido em processos como ajustamento osmótico, destoxificação de espécies reativas de oxigénio e proteção de macromoléculas, sendo também reserva de carbono e fonte de azoto. O objetivo do presente estudo foi investigar os efeitos da aplicação foliar de glicina betaína (25 mM) na atividade fotossintética de oliveiras (cv. Cobrançosa) em plena produção, cultivadas em regime de sequeiro na Terra Quente Transmontana (Suçães, Mirandela). A aplicação do bioestimulante foi efetuada no início do verão e a atividade fisiológica, centrada nas trocas gasosas e no estado hídrico, foi avaliada ao longo dos 3 meses seguintes. A aplicação de glicina betaína conduziu, em julho, a um aumento da taxa de fotossíntese e da eficiência intrínseca do uso da água durante o período da manha, e da condutância estomática durante a tarde. Por outro lado, as plantas tratadas com bioestimulante apresentaram aumento do conteúdo relativo em água no mês de agosto. Os resultados sugerem que a aplicação de glicina betaína provocou um aumento da atividade fisiológica a curto prazo, verificando-se perda de efeito a o longo do tempo. Justifíca-se a necessidade de estudos futuros no sentido de otimizar a concentração e o número de aplicações deste metabolito para obter uma melhor performance da oliveira em condições de sequeiro.

In Northeast Portugal, olive orchards cover over 75000 ha and involve approximately 36000 producers, being olive oil the only saleable product for many families. Despite the physiological defense strategies that olive trees dispose against summer stress, the projected climate change characterized by severe summer conditions, with low rainfall, excessive heat load and high irradiance leveis might affect this crop. Cropping practices for adaptation of olive orchards to climate change must be pursued. In this work we aimed to investigate the introduction of foliar applications of compounds that have shown a central role in stress tolerance in different plant species. The study was conducted in an organic orchard at Quinta do Prado, Lodões, Vila Flor (41°20'13. 3"N, 7°05'54. 2"W) and shows the impact of the application of arginine (l mM), jasmonate (100 |-iM) and kaolin (5%; w/v) on leaf gás exchange parameters at 6 different times between July and October 2016. Ali compounds, specially kaolin, contributed to the improvement of the photosynthetic activity of olive trees during measurements made during August and September, mainly due to lower stomatal limitations, although a drop of non-stomatal limitations were also recorded at midday period, namely by the end of August. The present study gives new insights about the effect ofthis new cropping practice for olive orchards that can help to mitigate the harsh climatic conditions projected forthe Mediterranean summers.

The predicted scenario of global warming anticipates severe summer conditions in the Mediterranean basin, with low water availability and excessive heat load. hlence, in arder to overcome the constrains that will affect olive groves and its socioeconomic value, new cropping practices focusing on water use efficiency must be investigated. In this work we aimed to investigate water management practices that can ensure the adequate compromise between yield and the quality of olive products. The study was conducted in Quinta do Prado, Lodões, Vila Flor (41°20'13. 3"N, 7°05'54. 2"W) and different irrigation strategies where investigated: full irrigation (Fl), equivalent to 100% of crop evapotranspiration (ETc), as control treatment, sustained déficit irrigation (SDI; 30% of ETc) and regulated déficit irrigation (RDI; 80% of ETc in phases l and III offruit growth and 10% of ETc in pit hardening stage). The impact of the treatments on leaf gás exchange and oxidative stress indicators during the 2016 summer was evaluated. The results indicate that both déficit irrigation strategies (DIS) allowed to maintain similar values of photosynthetic and transpjration rate and stomatal conductance as in Fl treatment, even in the afternoon period, although occasionally lower values were recorded during summer, namely in RDI plants. Meanwhile, despite the great disparity in the amount of water used among treatments, there were no significant differences in the degree of oxidative stress, judging by the comparative values of photosynthetic pigments, soluble proteins, total thiols and electrolyte leakage. Thus, the DIS used in this study allow an adequate physiological activity of olive trees and give new insights about the effect of these strategies in olive orchards. Since the field trial is located in a commercial farm, production costs, returns, and also fruit quality parameters are being recorded, analysis of which might give an economic insight regarding the sustainability of the implemented techniques.

The Mediterranean Basin is a climate change hot spot where substantial warming and lower water availability is predicted. This scenario poses considerable challenges to olive groves, a crop with great ecological and socioeconomic importance. ln order to overcome these constrains, new cropping practices focusing on water use efficiency must be investigated. ln this work we aimed to investigate water management practices that can ensure the adequate compromise between yield and the quality of olive products. The study was conducted in Quinta do Prado, Lodões, Vila Flor (41 °20'13.3"N, 7°05'54.2"W) and a full irrigation (FI) control, applied daily, equivalent to 100% of crop evapotranspiration (ETc), was compared with three deficit irrigation strategies (DIS): regulated deficit irrigation (RDI; 80% of ETc in phases I and III of fruit growth and 10% of ETc in pit hardening stage, phase TI; 56 % of the ETc in all season), sustained deficit irrigation (SDI; 27.5% of ETc), and sustained deficit irrigation adopted by the farmer (SDIAF; 21.2% of ETc, applied weekly). The impact of treatments on fruit yield and quality during 2016 were evaluated. Using FI treatment as reference, no significant influence of RDI and SDI treatments were felt in crop yield, while the SDlAF treatment reduced it significantly (P<O.Ol ). Fruit quality analysis showed that the SDI treatment Ied to higher antioxidant activity than in FI and SDIAF treatments. However, the SDIAF strategy led to higher accumulation of both total phenols and flavonoids (P<O.Ol ). The fruit fat content was significantly higher in deficit irrigation treatments, when compared to the FI treatment. lrrigation treatments also induced changes in fruit fatty acids profile (P<O.OOl) since palmitoleic acid (C16:1) decreased in the deficit irrigation treatments, linoleic acid (Cl8:2) decreased in the SDIAF treatment, and linolenic acid (C18:3) decreased in RDI and SDI treatments. Except for SDIAF, despite the great disparity in the amount of water used among treatments, there were no significant differences in fruit production. Hence, with an increase of 30% in water consumption, changing from the SDlAF to the SDl treatment, this particular farmer can increase the orchard production, without losing fruit fat content and antioxidant capacity. This work gives new insights about the effect of DlS when used in olive orchards and might help to illustrate the sustainability of these management practices.