Fostering sustainable water use in almond (Prunus dulcis Mill.) orchards in a semiarid Mediterranean environment

This work examines the long-term effects of deficit-irrigation (DI) practices in almond crop (Prunus dulcis Mill.) in agronomical and physiological terms. The trial was conducted during four-year monitoring period (2014–2017), in an experimental orchard (SW Spain), subjected to three irrigation regimes; i) a full-irrigation treatment (F_I), which received 100% of crop evapotranspiration (ET_C); ii) a regulated-deficit irrigation (RDI₅₀), which received 50% of ET_C during the kernel-filling period; and iii) a low-frequency deficit irrigation (LFDI), that was subjected to continuous periods of irrigation-restriction defined in terms of threshold values of leaf-water potential (Ψ_leaf) during the kernel-filling period. During the water stress period, there were monitored Ψ_leaf, stomatal conductance (g_s) and canopy temperature (T_C). Significant improvements in terms of water-use efficiency were found, as no differences in terms of yield between F_I and LFDI were found, leading to the conclusion that significant water savings (between 27 and 40%) can be achieved without compromising the yield. Moreover, threshold values of Ψ_leaf and thermal indicators were defined which will allow establishing future irrigation scheduling without compromising almond yield, especially when DI strategies are being applied.     

Obtaining from Grape Pomace an Enzymatic Extract with Anti-inflammatory Properties

Grape pomace, a winemaking industry by-product, is a rich source of bioactive dietary compounds. Using proteases we have developed an enzymatic process for obtaining a water-soluble extract (GP-EE) that contains biomolecules such as peptides, carbohydrates, lipids and polyphenols in soluble form. Of especial interest is its high polyphenol content (12 %), of which 77 % are flavonoids and 33 % are phenolic acids. The present study evaluates in vitro the potential anti-inflammatory effect of GP-EE by monitoring the expression of inflammatory molecules on N13 microglia cells stimulated with lipopolysaccharide (LPS). GP-EE decreases the mRNA levels of the inflammatory molecules studied. The molecules under study were as follows: inducible nitric oxide synthase (iNOS), tumor necrosis factor- α (TNF-α), interleukin-1β (IL-1β), the ionized calcium binding adaptor molecule-1(Iba-1) and the Toll like receptor-4 (TLR-4), as well as the iNOS protein level in LPS-stimulated microglia. Our findings suggest that, as a result of its ability to regulate excessive microglial activation, GP-EE possesses anti-inflammatory properties. Therefore, acting as a chemopreventive agent, it may be of therapeutic interest in neurodegenerative diseases involving neuroinflammation. We can, therefore, propose GP-EE as a useful natural extract and one that would be beneficial to apply in the field of functional foods.

     

Optimization of DH-line based recurrent selection procedures in maize under a restricted annual loss of genetic variance

Doubled haploid (DH) lines are increasingly being used in commercial hybrid maize (Zea mays L.) breeding. They allow for various quantitative genetic and logistic advantages provided that they are implemented in efficient and optimally allocated breeding procedures. In the present study, a new software was applied to optimize two recurrent selection (RS) schemes for hybrid maize breeding based on DH lines under a restricted annual budget and an upper limit for the relative annual loss of genetic variance. This software maximizes the expected gain from selection in general combining ability by means of quantitative genetic model calculations. Optimization results are compared for one, two, and three stages of testcross selection under different assumptions regarding the evaluation of lines per se and the annual budget. Results show that the optimum allocation of technical and budget resources to the individual steps of an RS program and the efficiency of alternative RS procedures are decisively determined by the number of selection stages. Under standard assumptions, one-stage selection was superior to two- and three-stage selection. Thus, shortening the length of an RS scheme considerably increases its efficiency. By intercrossing a reduced number of selected lines for starting a new RS cycle, the short-term response to selection may be increased, but the population size and, thus, the selection limits in the long run are diminished. Therefore, fair comparisons of alternative RS procedures require to define the intended time span for maximizing the genetic gain from RS and to restrict the relative annual loss of genetic variance accordingly.     

Modelling and control of non-persistent plant virus transmission for annual production cycles

When an insect carrying a non-persistent virus punctures a plant it loses part, or may be all, of its viral load. Using a differential equation model, we show that this is a critical factor affecting disease incidence levels when crops are under annual production cycles. Computer simulations suggest that relatively low vector pressure at the beginning of planting cycles decrease the disease progression. The model provides also approximations to disease incidences in subsequent plantings. Conditions for incidences to decrease or increase in time are supplied, which may be useful to assess the impact of some control strategies.     

A simulation of the effects of early eradication of nematode infected trees on spread of pine wilt disease

Pine wilt disease is currently among the most devastating pine tree plagues on earth. It is caused by the pinewood nematode Bursaphelenchus xylophilus in a perfect and well synchronized mutualistic relationship with beetles of the genus Monochamus. The disease has a fast and efficient mode of spread, which makes most of the efforts to control it practically insufficient. We investigate how early eradication of infected pine trees, i.e. eradication of trees which just ceased oleoresin exudation, may affect disease spread. In contrast to the sole eradication of killed trees, our results show that under an appropriate combination of eradication strategies: (1) there is a significant increase in the minimum pine density below which the disease fails to invade; (2) the region where reproductive Allee effects may take place are significantly enlarged. We implement optimal strategies for eradication through stochastic search optimization techniques, and conclude that disease extinction can be reached faster with an appropriate combination of eradication measures, minimizing the damage on healthy pine trees and operational costs.     

Genomic selection allowing for marker‐by‐environment interaction

Genomic selection has been routinely implemented in plant breeding in two stages. The first stage usually omits the marker information and estimates adjusted means of genotypes across environments. The second stage uses the adjusted means to predict genomic breeding values. However, if the effects of markers vary substantially between different environments, it may be important to account for this variation for varieties adapted to different environments. Using two maize data sets, we investigated whether modelling the marker‐by‐environment interaction can improve the predictive ability of genomic selection relative to modelling genotype‐by‐environment interaction alone. Modelling the marker‐by‐environment interaction did not substantially increase the predictive ability relative to modelling only the genotype‐by‐environment interaction for the two tested data sets. Thus, genomic selection, carried out in a stagewise fashion, such that the marker information is omitted until the last stage of the process, may suffice for most practical purposes. Moreover, predictive ability did not reduce substantially even when the number of markers with consistent effects across environments used for genomic prediction was reduced to about 50.     

Water use and fruit yield of mango (Mangifera indica L.) grown in a subtropical Mediterranean climate

Mango (Mangifera indica L.) is one of the most important fruit crops in tropical and subtropical regions worldwide. On the coast of Granada and Malaga (SE Spain), irrigated subtropical fruit species have been introduced and cultivated on terraces with a considerable economic importance as the only European production region. The subtropical fruit production in this zone is possible with intensive irrigation on terraces, which are economically more profitable than traditional rainfed crops (almond and olive), which have been replaced or abandoned. A 2-year monitoring period was conducted using drainage lysimeters to determine the crop coefficients (Kc) and fruit yield in mango (Mangifera indica L. cv. Osteen) orchards. Also, some quality parameters such as titratable acidity, total soluble solids, and vitamin C were evaluated under these conditions. The averaged Kc values of mango trees varied within production cycle of 0.43, 0.67, and 0.63 at flowering, fruit set, and fruit growth, respectively. In this study, the fruit yield under full water requirements (100% ET_C) averaged 24.1 kg tree^?1, amounting to 21.2 kg ha^?1 mm^?1 in terms of water-use efficiency. The quality parameters of the mango fruits harvested in the study area were satisfactory. Thus, this study highlights the need to optimize the irrigation-water use according to actual mango requirements, thereby achieving more sustainable Mediterranean subtropical farming in orchard terraces.     

Maternal differences for the reaction to ergot in unfertilized hybrid rye (Secale cereale)

European Journal of Plant Pathology - Claviceps purpurea causing ergot maintains to be a problem in commercial cytoplasmic male sterile (CMS)-based hybrid rye growing. The fungal spores compete...     

Comprehensive colorimetric study of anthocyanic copigmentation in model solutions. Effects of pH and molar ratio

New colorimetric variables have been defined in the uniform CIELAB color space to assess the quantitative and qualitative color changes induced by copigmentation and their incidence on visual perception. The copigmentation process was assayed in model solutions between malvidin 3-glucoside and three phenolic compounds (catechin, epicatechin, and caffeic acid) as a function of the pH and the pigment/copigment molar ratio. Along the pH variation, the greatest magnitude of copigmentation was obtained at pH 3.0, being significantly higher with epicatechin and caffeic acid. At high acidic pH, the main contribution of copigmentation to the total color was qualitative, whereas between pH 2.0 and 4.0, the main colorimetric contribution was quantitative. The contribution of epicatechin and caffeic acid to the color changes was more marked for the quantitative characteristics. On contrast, particularly at higher pH values, the qualitative contribution was more important in catechin copigmented solutions. Increasing copigment concentration induced perceptible color changes at molar ratios higher than 1:2, consisting in a bluish and darkening effect of the anthocyanin solutions. Among the different CIELAB attributes, hue difference was the best correlated parameter with the increase of copigment concentration, proving the relevance of this physicochemical phenomenon on the qualitative changes of anthocyanin color.