Modeling Sugar Beet Responses to Irrigation with AquaCrop for Optimizing Water Allocation

Process-based crop models such as AquaCrop are useful for a variety of applications but must be accurately calibrated and validated. Sugar beet is an important crop that is grown in regions under water scarcity. The discrepancies and uncertainty in past published calibrations, together with important modifications in the program, deemed it necessary to conduct a study aimed at the calibration of AquaCrop (version 6.1) using the results of a single deficit irrigation experiment. The model was validated with additional data from eight farms differing in location, years, varieties, sowing dates, and irrigation. The overall performance of AquaCrop for simulating canopy cover, biomass, and final yield was accurate (RMSE = 11.39%, 2.10 t ha−1, and 0.85 t ha−1, respectively). Once the model was properly calibrated and validated, a scenario analysis was carried out to assess the crop response in terms of yield and water productivity to different irrigation water allocations in the two main production areas of sugar beet in Spain (spring and autumn sowing). The results highlighted the potential of the model by showing the important impact of irrigation water allocation and sowing time on sugar beet production and its irrigation water productivity

Proline content of sugar beet storage roots: Response to water deficit and nitrogen fertilization at field conditions

Drought stress is one of the major factors causing profit loss of the sugar beet crop. The accumulation of proline, an indicator of water stress, has been reported in response to osmotic and salt stress in sugar beet leaves, but there is little information about its levels in storage roots. Proline in storage roots is potentially useful as indicator of situations that lead to decreased yield and quality of the root, such as drought stress and excess nitrogen. This study has been focused towards proline quantification in storage roots from field trials concerning irrigation, sugar beet variety and nitrogen fertilization. Water deficit is the main factor leading to proline accumulation in sugar beet roots. Excess N supply also increases proline levels, partially by increasing leaf area index (LAI) and exacerbating drought stress. The two varieties studied (Claudia and Ramona) had different responses to water shortage and to nitrogen. Maximum proline levels were measured in Claudia roots subjected to a combination of water shortage and excess N. A positive and significant correlation was found between proline and glucose levels in sugar beet roots, pointing to a relationship between stress responses, carbohydrate catabolism, and proline and glucose accumulation. This proposal was supported by the effect of treatments with di-1-p-menthene (anti-transpirant) and with DMDP (2,5-dihydroxymethyl-3,4-dihydroxypyrrolidina, a glycosidase inhibitor), which lead to decreased level of proline in non-irrigated Claudia sugar beet roots.Subdirección General de Proyectos de Investigación Científica y Técnica de España y FEDER (Unión Europea) IFD97-0893-CO3-01Universidad de Sevilla USE-MONTE P-96Junta de Andalucía (PAI) CVI 29

Efecto del riego por goteo de bajo volumen en el rendimiento del cultivo de fréjol variedad “Rojo del Valle” en los andes ecuatorianos

La aplicación del agua de riego por goteo en bajos volúmenes con alta frecuencia es una técnica de manejo del agua que permite maximizar la disponibilidad de oxígeno, agua y nutrientes en la solución del suelo para mejorar la actividad fisiológica de la planta. La investigación se realizó en el Valle de Tumbaco (provincia de Pichincha) para evaluar el efecto integral de esta técnica en la relación suelo – agua – planta. Se utilizó un diseño experimental de parcelas divididas con dos factores en estudio (métodos de aplicación del agua y dosis de fertilizantes), Goteo se denomina al manejo del agua convencional (riego continuo con dosis de fertilizantes 100%) y RPro el riego de bajo volumen de alta frecuencia (riego intermitente con dosis de fertilizantes 50%). Los resultados promedio (2018-2019) fueron: i) rendimiento: Goteo 3,11 t ha-1 y RPro 4,38 t ha-1; ii) lámina de agua aplicada: Goteo 368,15 mm y RPro 236,40 mm; iii) altura de la planta: Goteo 67,39 cm y RPro 62,13 cm; iv) vainas por planta: Goteo 20,17 y RPro 25,24; v) granos por vaina: Goteo 3,67 y RPro 4,04. En conclusión, el riego por goteo de bajo volumen de alta frecuencia en comparación con el goteo continuo permitió obtener un incremento en el rendimiento del 40,84%, un ahorro de agua del 55,73%, un ahorro de fertilizantes del 50% y el ciclo vegetativo se redujo en dos semanas