Peeling has no effect on respiration and ethylene production and only minimal effect on quality of fresh white asparagus spears

Fresh white asparagus spears were subjected to peeling or left unpeeled before storage at 10 °C for 7 days. CO₂ and ethylene production rates were determined during storage, while color, toughness and DPPH radical scavenging activity as well as soluble solids, total soluble phenols and nitrate content were determined before and after storage in both peeled and unpeeled spears. Peel CO₂ and ethylene production rates were also determined during storage. Spears subjected to peeling were more tender, and had lower lightness and chroma and higher hue angle values compared to the unpeeled ones. However, both peeled and unpeeled spears had similar DPPH radical scavenging activity, soluble solids, total soluble phenols and nitrate contents. Peeling resulted in increased CO₂ and C₂H₄ production rates, but peel contributed to total increase of CO₂ and C₂H₄ production. As the measured metabolic activity of the peeled asparagus spears was similar to that of the unpeeled, peeling did not adversely affect quality during storage.     

Seasonal changes of macro- and micro-nutrients concentration in olive leaves

Leaves of olive (Olea europaea var. minor rotunda) were collected from mature non-irrigated trees in an “off” year, at monthly intervals, from May 2015 to April 2016. Leaf concentrations of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn) and boron (B) were determined. Seasonal fluctuation curves were developed for each nutrient, in order to use them for interpretation of leaf analysis. Concentrations of N, P, K, Ca and Mg showed significant fluctuation throughout the year, while B, Fe, Mn and Zn showed less intense changes. Nutrient accumulation varied according to tree vegetative growth and weather conditions.     

Detection of biotic and abiotic stresses in crops by using hierarchical self organizing classifiers

Hyperspectral signatures can provide abundant information regarding health status of crops; however it is difficult to discriminate between biotic and abiotic stress. In this study, the case of simultaneous occurrence of yellow rust disease symptoms and nitrogen stress was investigated by using hyperspectral features from a ground based hyperspectral imaging system. Hyperspectral images of healthy and diseased plant canopies were taken at Rothamsted Research, UK by a Specim V10 spectrograph. Five wavebands of 20 nm width were utilized for accurate identification of each of the stress and healthy plant conditions. The technique that was developed used a hybrid classification scheme consisting of hierarchical self organizing classifiers. Three different architectures were considered: counter-propagation artificial neural networks, supervised Kohonen networks (SKNs) and XY-fusion. A total of 12 120 spectra were collected. From these 3 062 (25.3%) were used for testing. The results of biotic and abiotic stress identification appear to be promising, reaching more than 95% for all three architectures. The proposed approach aimed at sensor based detection of diseased and stressed plants so that can be treated site specifically contributing to a more effective and precise application of fertilizers and fungicides according to specific plant’s needs.     

Influence of biotic factors on the mechanical properties of wood,taking into account the time of harvesting

The aim of the present paper is to investigate the influence of biotic factors (fungi and insects) on the mechanical properties of wood through the effect of blue-stain, taking into account the time of harvesting and the time of stay of wood in the forest. Specifically, the resistance to axial compression and to bending (modulus of rupture (MOR)) was studied using infected specimens of Scots Pine (Pinus sylvestris) and Norway Spruce (Picea abies) (the usual types of wood used in woodwork). The specimens were obtained from logs of Scots Pine and Norway Spruce that were harvested in three different seasons of year, namely in July 2012, November 2012 and June 2013, respectively, in the forest of Elatia-Greece, and the attack pace by biotic factors with respect to the time of logging was studied. The placement of the experimental surfaces of each type of tree was made on skid road and in the stand. Totally, 120 laboratory measurements in axial compression and 120 measurements in bending (MOR) took place. The results proved that blue-stain hardly affect the mechanical properties of both wooden species and particularly the specimens that were derived during the winter logging.     

Physiological,nutritional and growth responses of melon (Cucumis melo L.) to a gradual salinity built-up in recirculating nutrient solution

Minimizing salinity impacts on yield in melon crops cultivated in closed-loop hydroponic systems requires better understanding of the physiological impact of gradual salt accumulation in the recycled solution. To attain this objective, different sodium chloride (NaCl) concentrations in the irrigation water, i.e. 0.7, 2.5, and 5 mM, were applied in two cropping seasons (winter-spring;WS and spring-summer;SS). In both seasons plant biomass and yield were negatively affected only in high NaCl-treated plants, due to stomatal limitations, which restricted carbon dioxide (CO₂) diffusion into the leaf, osmotic and salt-specific effects. However, a progressive NaCl built-up to maximum concentrations in the root zone solution of 15 (WS) and 20 mM (SS), enabled plants to preserve several physiological mechanisms, thereby adjusting growth and yield without impairing fruit quality. Our results suggest that the use of irrigation water, containing up to 2.5 mM NaCl, is feasible in melon crops grown in closed-loop hydroponic systems, without yield and quality losses.     

Determination of phospholipids in olive oil by 31P NMR spectroscopy

A nondestructive analytical method based on NMR spectroscopy was developed for the determination of phospholipids in olive oil. The phospholipids extracted from virgin olive oil with a mixture of ethanol/water (2:1 v/v) were identified and quantified by high resolution (31)P NMR spectroscopy. The main phospholipids found in olive oil were phosphatidic acid, lyso-phosphatidic acid, and phosphatidylinositol. Validation of the (31)P NMR methodology for quantitative analysis of phospholipids in olive oil was performed. Sensitivity was satisfactory with detection limits of 0.25-1.24 mumol /mL. In addition, the composition of fatty acids in phospholipids model compounds and those in olive oil samples was estimated by employing one- and two-dimensional (1)H NMR. The results indicated that the fatty acid composition in phospholipids and triacylglycerols of olive oil was similar.     

Ascorbic acid–cyclodextrin complex alters the expression of genes associated with lipid metabolism in bovine in vitro produced embryos

Ascorbic acid (AC) used as antioxidant in embryo culture is very sensitive and degrades unavoidably in aqueous solution. Methyl‐β‐cyclodextrin (CD) improved the stability of AC in solution to elevated temperature, light, humidity and oxidation. The aim of this study was to evaluate the effect of the complex AC‐CD during in vitro maturation (IVM) or in vitro culture (IVC) on oocyte developmental competence and subsequent embryo development and quality. AC‐CD (100 µM) was added to IVM media, and maturation level and embryo development were examined. Matured oocytes, their cumulus cells and produced blastocysts were snap‐frozen for gene expression analysis by RT‐qPCR. Besides, in vitro‐produced zygotes were cultured with 100 µM of AC‐CD and blastocysts were as well snap‐frozen for gene expression analysis. A group without AC‐CD (control^?) and other with CD (control⁺) were included. No differences were found on maturation, cleavage or blastocyst rates. However, in matured oocytes, AC‐CD downregulated BAX, GPX1 and BMP15. In cumulus cells, AC‐CD downregulated BAX/BCL2 and GSTA4 while upregulated BCL2 and CYP51A1. The expression of SL2A1, FADS1, PNPLA and MTORC1 was downregulated in blastocysts derived from oocytes matured with AC‐CD, while in blastocysts derived from zygote cultured with AC‐CD, CYP51A1 and IGF2R were downregulated and PNPLA2 was upregulated. In conclusion, AC‐CD in both IVM and IVC media may reduce accumulated fat by increasing lipolysis and suppressing lipogenesis in blastocysts derived from both oocytes and zygotes cultured with AC‐CD, suggesting that CD improves the quality of embryos and bioavailability of AC during IVM and IVC.