Osmotic stress affects physiological responses and growth characteristics of three pistachio cultivars

Pistachio (Pistacia vera L.) has a high tolerance to drought and soil salinity. Although adult pistachio trees are well known to be drought tolerant, the studies on physiological adaptation of pistachio cultivars to drought are limited. Therefore, three pistachio cultivars, i.e., Akbari, Kaleghochi, and Ohadi were subjected to three osmotic drought stress treatments: control (-0.1 MPa), moderate (-0.75 MPa) and severe drought (-1.5 MPa) stress using PEG 6000 for a 14-day period. All drought stress treatments decreased net photosynthesis (Pn), stomatal conductance (gs), intercellular CO2 concentration (Ci), and transpiration rate (E), but Ohadi maintained better its photosynthetic capacity compared to Akbari and Kaleghochi. Maximum quantum yield of PSII photochemistry (Fv/Fm), effective PSII quantum yield (UPSII) and photochemical quenching (qP) were also reduced. The chlorophyll fluorescence parameters indicated that Akbari was more susceptible to the applied drought stress. Drought stress levels decreased chlorophyll pigments, fresh weight, stem elongation, leaf nitrogen content (N), leaf water potential and increased water use efficiency (WUE). Proline increased strongly under drought stress for Akbari. After 2 weeks of stress a recovery of 2 weeks was applied. This period was insufficient to fully restore the negative effects of the applied stress on the studied cultivars. Based on the reduction of photosynthesis and the increase of the proline content Akbari seems more sensitive to the applied drought stress

Functional agrobiodiversity and agroecosystem services in sustainable wheat production. A review

Agrobiodiversity can improve the sustainability of cropping systems in a context of low external inputs and unpredictable climate change. Agrobiodiversity strategies to grow wheat are breeding ad hoc cultivars for organic and low-input systems, wheat–legume intercrops and living mulches, cultivar mixtures, and the use of genetically heterogeneous populations. However, applying those strategies can fail due the lack of a well-focused framework. Therefore, we need a better integration between breeding and management and a clear focus on crop traits related to key agroecosystem services. Here, we review the use of agrobiodiversity in wheat production, focusing on breeding and management. We discuss five agroecosystem services: (1) weed reduction, (2) nitrogen use efficiency, (3) abiotic stress tolerance, (4) disease and pest reduction and (5) yield and yield stability. We categorise agrobiodiversity into functional identity, functional composition, and functional diversity, in order to link crop traits to agroecosystem services. Linking crop traits to agroecosystem services could in turn lead to concrete options for farmers and policy. We discuss the relations between crop identity and crop heterogeneity. We also discuss the partitioning of crop heterogeneity between functional composition and functional diversity