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Highlights • Soils from marl, serpentine and serpentinized peridotite were used as substrates. • Most foliar nutrients were significantly lower in the serpentinized soil. • Photosynthesis was significantly lower in the serpentinized peridotite soil. • Increased levels of phenols, TFC and FRAP were found in the serpentinized soil. • Differential tolerance to serpentine stress between 'Wonderful' and 'Acco' existed. Abstract It was investigated if differential genotypic tolerance of two pomegranate cultivars ('Wonderful' and 'Acco') to serpentine stress existed. For this purpose, pomegranate plants were grown outdoors, in three soil substrates (from parent material marl, serpentine and serpentinized peridotite). The results indicated that growth, most foliar nutrient concentrations, total chlorophyll content, chlorophyll fluorescence and photosynthetic rate, for both genotypes, were significantly lower in the serpentinized peridotite soil (severe stress). In contrast, higher levels of total phenolics, total flavonoid content (TFC) and FRAP, were found in the serpentinized soil. Lower tolerance index to stress in the serpentinized soil was found for the cultivar 'Acco', than for 'Wonderful'. Overall, the physiological and antioxidant response of 'Acco' was worse, than that of 'Wonderful', under serpentine stress. In conclusion, despite the lower Ni, Cr and Mg accumulation of 'Acco' (compared to 'Wonderful'), its lower tolerance indices in the serpentinized soil probably shows its higher tissue sensibility to serpentine stress. Thus, this genotype should not be preferred for cultivation in soils presenting high degree of serpentinization (excess Mg concentrations). In contrast, from the tolerance indices of both genotypes in the serpentine soil, it is concluded that a mild stress existed in this case. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this study was the comparison of the effect of two Mn sources (MnSO4·H2O, MnEDTA) which were applied at various concentrations (0, 200, 400, 800, and 1200mgMnl−1) to the leaves of ‘Washington navel’ orange trees in order to correct Mn deficiency. One hundred and seventy days after the foliar application of Mn solutions, the mean Mn concentrations in the leaves treated with MnSO4·H2O (200, 400, 800 or 1200mgMnl−1) or MnEDTA (400, 800 or 1200mgMnl−1) were significantly higher than those of the control leaves. Manganese sulfate (MnSO4·H2O) was more effective than MnEDTA regarding the improvement of the leaf Mn concentrations of the trees, when applied at equal Mn concentrations. Finally, the leaf Mn concentrations were in the sufficiency range (>25mgkg−1 d.w.), only after the application of 800 or 1200mgMnl−1 as MnSO4·H2O. [Copyright &y& Elsevier]

A greenhouse experiment was carried out in order to study the effects of B excess (2.50 mg B l−1) on physiological (B concentration and distribution, gas exchange parameters, chlorophyll concentration and fluorescence) and anatomical (leaf structure and chloroplast ultrastructure) characteristics of ‘Navelina’ orange plants grafted on sour orange and Swingle citrumelo rootstocks. Boron concentrations of all plant parts increased with increasing B concentration in the nutrient solution, following the order: old leaves>young leaves>bark of rootstock>root>stems of scion>stem of rootstock>wood of rootstock. ‘Navelina’ plants were less sensitive to excess B when grafted on Swingle citrumelo than on sour orange. This was due to the lesser absorption of B from the nutrient solution and its greater total retention in the rootstock stem of plants grafted on Swingle citrumelo than those grafted on sour orange rootstock, thus limiting the amount of B that reached the leaves of plants grafted on Swingle citrumelo rootstock. Increased B concentration in the nutrient solution brought about a decrease of leaf thickness, mainly due to reduced spongy parenchyma tissue. Although the size of chloroplasts decreased in response to high B concentration in the nutrient solution, their shape was not altered. Excess B further decreased the relative volume of chloroplast thylakoids and increased the relative volume of plastoglobuli. Finally, the leaves of ‘Navelina’ plants grown under 0.25 mg B l−1 exhibited higher concentrations of chlorophyll as well as higher values of chlorophyll fluorescence parameters (Fv/Fm, Fv/F0) and of photosynthetic rates in contrast to the plants grown under 2.50 mg B l−1. [Copyright &y& Elsevier]

• Olive plants were fertilized with manures or a controlled release fertilizer (CRF). • The highest biomass, macronutrient content and PSII activity were found in the CRF. • Significantly lower photosynthetic rate and stomata opening were recorded in the CRF. • The lowest foliar P, K, Mg, Zn and Cu concentrations were found in the CRF. • The higher macronutrient accumulation in the CRF was owed to the higher biomass. Organic fertilization has been proposed as an alternative method, in the frame of sustainable agriculture, to enhance soil fertility and satisfy the nutritional needs of crops, without the input of chemical fertilizers. A six-month pot experiment, with 3 soil amendments, used as organic fertilizers (cow manure-CM, goat manure-GM, and their mixture, i.e. CM + GM) and a controlled release fertilizer (CRF) was conducted, in order to investigate if the growth, nutrient uptake, photosystem II (PSII) activity, photosynthetic rate and total sugars of Olea europaea L. (cv. 'Koroneiki') plants were influenced by the kind of fertilization. The highest plant biomass, macronutrient content and PSII activity were found in the CRF treatment. In contrast, significantly lower photosynthetic and transpiration rates were recorded in the CRF due to the lower stomatal conductance. Translocated sugars were higher in the CM + GM treatment, while total sugar concentration did not significantly differ among the treatments. Despite the highest content of all macronutrients, Fe and Mn recorded in the CRF, the lowest foliar P, K, Mg, Zn and Cu concentrations revealed that the higher nutrient accumulation, compared to the organic treatments, should be ascribed to the higher plant biomass, rather than to higher nutrient uptake. From the above data, it is clear that the kind of organic/inorganic fertilization significantly influenced soil organic C content, fertility, growth, nutrient uptake and the physiology of olive plants. Thus, the kind of manure(s) used to enhance soil fertility and support crop production should be seriously taken into consideration by the olive growers before its/their use. [ABSTRACT FROM AUTHOR]

We tested the effect of water-temperature during the larval phase on sea bass sensitivity to current-induced lordosis. During larval rearing phase, fish were subjected to two different water temperatures (15 or 20 °C), with the rest of the rearing parameters remaining identical between the different populations. During the pregrowing phase, the different populations were subjected to four different water-current velocities (WCV), with the rest of the environmental conditions remaining common. At the end of the pregrowing phase (43.5±0.8 mm TL), lordosis was more frequent in fish that developed at 20 °C (p <0.05), independently of the WCVs applied. The anatomic analysis of the deformed fish revealed a significant effect of early developmental temperature on the severity of the deformity, with the 15 °C populations showing the lower severity in respect to the angle of lordosis and the number of affected vertebrae (p <0.05). Two weeks of exposure to WCVs (24.0±0.8 mm TL) resulted in 15 °C populations presenting the lower incidence of lordosis and the higher incidence of normal fish in all WCVs, except 50%, tested (p <0.05). At this stage, WCV had a clear effect on lordosis development in populations coming from both developmental temperatures (p <0.05), although at 15 °C these effects were more pronounced. Fish that developed at 20 °C showed significantly higher incidence of deformed vertebral centra and arches than those developed at 15 °C (p <0.05). These early anatomical signs were evident in samples taken at the end of the larval rearing phase (15.7±1.0 mm TL), as well as 1 week after the onset of exposure to WCVs (21.4±0.6 mm TL). In both cases, their incidence was significantly higher in fish that initially developed at 20 °C than at 15 °C. [Copyright &y& Elsevier]