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Mulching the soil with organic-based formulations (hydromulching) is a sustainable alternative to plastic mulching that is here hypothesized to maintain crop production under drought stress by hormonal and metabolic regulation of source–sink relationships. To test this hypothesis, artichoke plants were grown on non-mulched soil and on soil mulched with polyethylene and three different organic mixtures, and subjected to optimal and reduced irrigation regimes. Under drought stress, the growth parameters were higher in plants grown with the different mulching treatments compared to non-mulched plants, which was related to a higher photosynthetic rate and water-use efficiency. Importantly, mulching-associated growth improvement under stress was explained by higher sucrolytic activity in the leaves that was accompanied by a decline in the active cytokinins. Besides this, salicylic acid decreased in the leaves, and abscisic acid and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid were impaired in the artichoke heads, which is associated with better regulation of photoassimilate partitioning. Taken together, these results help to explain the hydromulching-associated growth improvement of artichokes under water stress through the hormonal regulation of sucrose metabolism, which could be very useful in future breeding programs for drought tolerance. [ABSTRACT FROM AUTHOR]

Rootstock breeding for vegetable crops includes desirable traits such as compatibility with the scion, increased productivity and quality under stressful environments and improved use of soil, water and fertilizer resources. The effects of three commercial rootstocks (Atlante, Creonte and Terrano) on the agronomical and physiological responses of a commercial sweet pepper variety (cv Herminio) to deficit irrigation (50% of optimal) have been studied. Although the three rootstocks increased total and marketable yield under control and deficit irrigation, Creonte produced the most productive and water use efficient plants, with until 25% more marketable yield than the ungrafted cv Herminio, and about 10% more than the other rootstocks, although in detriment of some chemical fruit quality traits. Moreover, the plants grafted onto Creonte registered the highest photosynthetic activity and leaf water content and more stable leaf area and biomass under water stress, while those parameters were more reduced in the other graft combinations. These Creonte-mediated effects were not related to root biomass (since it was more affected by the stress in this rootstock) but rather to the capacity of maintaining a high reproductive/vegetative ratio, while Atlante is a vigorous vegetative rootstock and Terrano is rather a dwarfing-reproductive rootstock that produces efficient compact plants without negative effects on fruit quality. [ABSTRACT FROM AUTHOR]

Salinity provokes an imbalance of vegetative to generative growth, thus impairing crop productivity. Unlike breeding strategies, grafting is a direct and quick alternative to improve salinity tolerance in horticultural crops, through rebalancing plant development. Providing that hormones play a key role in plant growth and development and stress responses, we hypothesized that rootstock-mediated reallocation of vegetative growth and yield under salinity was associated with changes in the hormonal balance. To test this hypothesis, the hybrid pepper variety (Capsicum annuum L. "Gacela F1") was either non-grafted or grafted onto three commercial rootstocks (Creonte, Atlante, and Terrano) and plants were grown in a greenhouse under control (0 mM NaCl) and moderate salinity (35 mM NaCl) conditions. Differential vegetative growth versus fruit yield responses were induced by rootstock and salinity. Atlante strongly increased shoot and root fresh weight with respect to the non-grafted Gacela plants associated with improved photosynthetic rate and K+ homeostasis under salinity. The invigorating effect of Atlante can be explained by an efficient balance between cytokinins (CKs) and abscisic acid (ABA). Creonte improved fruit yield and maintained the reproductive to vegetative ratio under salinity as a consequence of its capacity to induce biomass reallocation and to avoid Na+ accumulation in the shoot. The physiological responses associated with yield stability in Creonte were mediated by the inverse regulation of CKs and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid. Finally, Terrano limited the accumulation of gibberellins in the shoot thus reducing plant height. Despite scion compactness induced by Terrano, both vegetative and reproductive biomass were maintained under salinity through ABA-mediated control of water relations and K+ homeostasis. Our data demonstrate that the contrasting developmental and physiological responses induced by the rootstock genotype in salinized pepper plants were critically mediated by hormones. This will be particularly important for rootstock breeding programs to improve salinity tolerance by focusing on hormonal traits. [ABSTRACT FROM AUTHOR]

Greenhouse peppers are one of the most important crops globally. However, as in any production activity, especially agricultural, they are subject to important risk factors such as price fluctuations, pests, or the use of bad quality water. This article aims to evaluate the viability of these types of crops by using discounted cash flows. Risk evaluation has been carried out through the analysis of pepper plantations for 2016 and 2017. The traditional application of this tool has significant limitations, such as the discount rate to be used or the estimation of future cash flows. However, by using discount functions that decrease over time in combination with decoupled net present value, these limitations are expected to improve. The use of decoupled net present value has permitted an increase in the accuracy and quantification of risks, isolating the main risks such as price drops (EUR 3720 ha−1 year−1) and structural risks (EUR 1622 € ha−1 year−1). The use of decreasing discount functions has permitted a more realistic investment estimation. Finally, the sensitivity analysis shows that decoupled net present value (DNPV) is little affected by changes in interest rates in contrast to traditional net present value (NPV). [ABSTRACT FROM AUTHOR]

The actual climate crisis scenario is aggravating the abiotic stress episodes that crop plants have to face. Salinity is one of the most important abiotic stresses directly impairing plant growth and productivity. Several strategies have been developed to minimize the negative effects of salinity in agricultural industry, mainly at the plant level, while management strategies, such us the control of microclimate conditions and light quality over plant canopy, have also been used. Indeed, shading plants with photoselective nets has been considered an efficient management strategy to modulate solar radiation to improve crop productivity. The aim of this work was to gain insights about the physiological factors underlying the salinity-alleviating effect of using red shading nets. For that, pepper plants (Capsicum annuum L.) were grown under control (0 mM NaCl) and moderate salinity (35 mM NaCl) conditions, with half of the plants covered with a red net (30% shading). The shoot growth impairment provoked by salinity was in part minimized by shading plants with red nets, which can be explained by their higher capacity to exclude Na+, control of K+ homeostasis and regulation of hormonal balance. Indeed, the concentrations of the most active cytokinin in pepper, trans-zeatin, as well as its metabolic precursor, zeatin riboside, increased in shaded plants, associated to shoot growth recovery and photosynthetic rate maintenance under salinity. Furthermore, the stress-related hormone abscisic acid (ABA) increased with salinity but in a lower extend in the plants shaded with red nets, suggesting a fine tune of stomata opening by ABA which, in crosstalk with salicylic acid increment, improved plant water relations. Likewise, the concentrations of gibberellins and the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid, also changed during salinity stress in shaded plants but those changes were uncoupled of growth responses as indicated by the principal component analysis and thus they seem to play a minor role. Our data demonstrate that shading pepper plants with red nets is an efficient management strategy to modulate microclimate conditions at crop level thus controlling the ion homeostasis and hormonal balance of the plant to cope with salinity stress. This is especially important due to the actual and expected changes of the global climatic conditions. [ABSTRACT FROM AUTHOR]

Drought is considered as one of the major limiting factors to plant growth and productivity. Drought stress reduces stomatal conductance, affecting water relations and decreasing CO2 assimilation rate and photosynthesis. Several strategies have been developed to alleviate the negative effects of drought in the agricultural industry. One of these strategies is the use of the mulching technology, which retains water in the soil surface. Knowing that hormones play a key role in plant growth and drought stress responses, we hypothesized that the use of a new ecological mulching technology called hydromulching would improve growth over bare soil under drought stress through changes in the hormonal balance. To test this hypothesis, escarole plants (Cichorium endivia L.) were grown in pots filled with coco fiber, non-covered (bare soil) or covered with polyethylene film (PE) and three types of hydromulches made up with recycled additives: wheat straw (WS), rice hulls (RH), and substrate used for mushroom cultivation (MS). Half of the plants were subjected to drought by reducing the volume of irrigation water to 70% of crop evapotranspiration. Despite drought stress impaired escarole growth-related parameters in all treatments, plants mulched with MS maintained significantly superior growth, due to improved plant water relations and photosynthetic function. This can be explained by an efficient interaction hydromulch/soil/plant in regulating the hormonal balance under water depletion. Indeed, the concentrations of the active cytokinins (CKs), trans-zeatin and isopentenyladenine, were higher in plants grown with MS treatment, associated with shoot growth-enhancing and photosynthetic rate maintenance under stress conditions. The concentrations of the stress-related hormone, abscisic acid (ABA), varied antagonistically to those of the active CKs. In this regard, ABA increased with drought but to a lower extent in MS plants thus regulating stomata opening, which, in crosstalk with the ethylene precursor 1-aminocyclopropane-1-carboxylic acid and salicylic acid, improved plant water relations. The results obtained demonstrate that hydromulching is an efficient and sustainable management strategy to ameliorate the drought effects on escarole plants through fine regulation of the CKs/ABA balance, which will be of utmost interest and applicability in the actual climate change scenario. [ABSTRACT FROM AUTHOR]

Plant growth regulators (PGRs) may have an important role in regulating both yield and fruit quality during the production of sweet pepper in controlled-environment greenhouses, but the uncertainly of results – due to the specificity of the plant response – could limit their use and potential benefits. Therefore, we investigated the effect of the foliar spraying of abcisic acid (ABA), gibberellic acid (GA 3 ) and indole-3-acetic acid (IAA) on fruit colour, concentrations of carbohydrates, ions and amino acids, plant growth and total fruit yield. Although yield was decreased by the GA 3 and ABA treatments, GA 3 augmented plant height and the levels of tyrosine, phosphate, sulphate, iron and phosphorus while decreasing the amounts of glucose and fructose. The foliar applications of IAA did not produce any change when compared with the control plants, while plants treated with ABA had decreased levels of sucrose but higher levels of iron. GA 3 , applied fortnightly, produced a significant improvement in the fruit quality of sweet pepper but did not significantly increase total yield. Further studies will be necessary to determine the best GA 3 concentration and frequency of application, to obtain greater benefits for human consumption this important crop. [ABSTRACT FROM AUTHOR]