Physiological response of post-veraison deficit irrigation strategies and growth patterns of table grapes (cv. Crimson Seedless)

To determine whether partial root-zone drying (PRD) offers physiological advantages compared with regulated deficit irrigation (RDI), a 3 year long-experiment was conducted on a commercial vineyard of ‘Crimson Seedless’ table grapes (Vitis vinifera L.). Four different drip irrigation treatments were imposed: (i) a Control treatment irrigated at 110% of seasonal crop evapotranspiration (ETc), (ii), a regulated deficit irrigation (RDI) treatment irrigated similar to Control before veraison and at 50% of the Control treatment post-veraison, (iii) a partial root-zone drying (PRD) irrigated similar to RDI but alternating (every 10–14 days) the dry and wet side of the root-zone, and (iv) a null irrigation treatment (NI) which only received the natural precipitation and occasional supplementary irrigation when midday stem water potential (Ψs) dropped below −1.2 MPa. Post-veraison, PRD vines accumulated greater localized soil and plant water deficit at midday than RDI vines, but maintained similar pre-dawn water potential (Ψpd) values. Stomatal conductance (gs) of PRD vines remained high, likely because there was sufficient root water uptake from irrigated soil. Xylem ABA concentration ([ABA]xylem) did not change yet intrinsic WUE (WUEi) decreased compared to RDI vines, probably because PRD induced greater root density and root development at depth, allowing greater water uptake from roots in the wet part of the soil profile. Vegetative growth was only decreased by severe deficit irrigation (NI) although total leaf area index (LAI) was also affected by PRD in the 1st and 3rd year.. PRD can be considered a useful strategy in semiarid areas with limited water resources because sustained water use maintained assimilation rates despite greater stress than conventional RDI strategy, which may be related to root and morphological adjustment

Influencia del riego deficitario en la aparición de desordenes fisiológicos en cerezas ‘Prime Giant’

Comunicación presentada al XXXVII Congreso Nacional de Riegos, celebrado en Don Benito del 4 al 6 de Junio de 2019 y organizada por la Asociación Española de Riegos y Drenajes y la Universidad de ExtremaduraSe describen los resultados agronómicos obtenidos en un ensayo de riego deficitario controlado realizado en cerezos (Prunus avium L.) combinación ’Prime Giant’/SL64, durante cuatro campañas (2015-2018) en Jumilla (Murcia, España). Los tratamientos de riego ensayados fueron: CTL, regado al 110% ETcg (evapotranspiración del cultivo bajo riego por goteo) durante toda la campaña de riego y RDC con riego al 100% de ETcg durante precosecha y diferenciación floral y al 55% de ETcg el resto de postcosecha. Se monitorizó el potencial matricial de agua en el suelo (Ψm) y se midió periódicamente el potencial hídrico de tallo a mediodía (Ψt). Los diferentes volúmenes de riego promedios aplicados anualmente, 6949 y 4249 m3 ha-1 para CTL y RDC respectivamente, provocaron diferencias significativas en la disponibilidad de agua para la planta y en su estado hídrico durante la postcosecha de todos los años de estudio. Sin embargo, estas diferencias no provocaron que el rendimiento de los cerezos sometidos a RDC fuera menor o mayor proporción de frutos dobles, cuya presencia resultó altamente dependiente de la temperatura del aire durante los primeros días de la postcosecha del año previo. Sí que se observó que los frutos de los árboles bajo RDC presentaban una menor proporción de frutos partidos en cosecha y en los análisis de inducción de partidura en laboratorio.• Ministerio de Economía, Industria y Competitividad del Gobierno de España (MINECO) y Fondo Europeo de Desarrollo Regional (Ref. AGL2016-77282-C3-3-R y AGL2013-49047-C2-1-R) • Fundación Séneca de la Región de Murcia (Grupo de excelencia 2016-2019 Ref. 19895/GERM/15) • Universidad Politécnica de Cartagena (UPCT): beca de iniciación a la actividad investigadora (Víctor Blanco

Soil greenhouse gas emissions and crop production with implementation of alley cropping in a Mediterranean citrus orchard

The implementation of alley cropping in orchards has been suggested as a sustainable strategy to increase farmer revenues by crop diversification, enhance soil organic matter (SOM) and fertility, water retention, overall biodiversity, and contribute to climate change mitigation. Thus, the objective of this study was to assess if alley cropping with annual crops can contribute to i) mitigate soil greenhouse gas (GHG) emissions, ii) enhance C sequestration in a semiarid Mediterranean irrigated citrus orchard, and iii) increase land productivity. For this, two different treatments were established: i) conventional mandarin monoculture (MC) with no alley cropping; and ii) mandarin diversified with alley cropping of barley/vetch and fava bean (DIV). Measurements of soil CO2 and N2O emissions were periodically performed (every 7–20 days) during two years. Soil CO2 emission rates followed the soil moisture trend, and showed no significant differences between treatments. As an average, soil CO2 emission rates were 147 mg m-2 h-1 in MC and 196 mg m-2 h-1 in DIV. Soil N2O emission rates were not correlated to soil moisture nor temperature, and showed average values of 0.026 mg m-2 h-1 in MC and − 0.002 mg m-2 h-1 in DIV. Alley cropping did not contribute to significantly increase soil organic C and total nitrogen in two years’ time. With regard to production, mandarin yield showed no significant differences between treatments, but alley crops contributed to complementary commodities to the main cash crop, increasing overall land productivity. Thus, alley cropping in irrigated Mediterranean orchards has no significant effect on soil C sequestration and GHG emissions at short-term, with increased land productivity owing to new commodities grown in the alleys. These results confirm that under semiarid Mediterranean climate, long periods are needed to efficiently assess soil C sequestration potential of sustainable practices in orchards.This work was supported by the European Commission Horizon 2020 Project Diverfarming [Grant agreement 728003]. Raúl Zornoza acknowledges the financial support from the Spanish Ministry of Science, Innovation and Universities through the “Ramón y Cajal” Program [RYC-2015-18758].Peer reviewe

Irrigation Protocols in Different Water Availability Scenarios for ‘Crimson Seedless’ Table Grapes under Mediterranean Semi-Arid Conditions

For three consecutive years (2015–2017), two deficit irrigation (DI) strategies were used in a 12-year old vineyard (cv. ‘Crimson Seedless’) to implement a sustainable irrigation protocol according to the available water for the farmer. Four different irrigation treatments were assessed: (i) Control (CTL), irrigated to satisfy the maximum crop water requirements throughout the entire growing season; two DI treatments irrigated as CTL except during post-veraison, when the vines were irrigated at 50% CTL: (ii) Regulated Deficit Irrigation (RDI); and (iii) Partial Root Drying (PRD), alternating the wet and dry sides of the root zone, and (iv) irrigated according to the criteria followed by the farmer (FARM), and conditioned by the availability of water each season. The DI strategies resulted in a 50% increase in water use efficiency in the first two years and 81% during the third year. Weekly deficit irrigation protocols are proposed, which specify a maximum difference of 0.22 MPa of midday stem water potential with respect to well-watered vines for a range of irrigation water availabilities between 4000 and 7000 m3 ha−1. An applied water prediction model based on the Gaussian regression using day of the year and maximum temperature of the day is also proposed.This research was funded by the European Union (project IRRIMAN LIFE13 ENV/ES/000539), and International Joint Programming Actions 2017 contemplated in the National R&D&I Programme oriented towards the challenges of society by the Ministry of Economy, Industry and Competitiveness—National Research Agency (AEI) (PCIN-2017-091).Peer reviewe