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Research Project
Produção de lúpulo nacional: uma estratégia para a sustentabilidade
Funder
Authors
Publications
Response of hops to algae-based and nutrient-rich foliar sprays
Publication . Afonso, Sandra; Arrobas, Margarida; Rodrigues, M.A.
Over recent years, some hopyards of northeast Portugal have presented poorly developed
plants and reduced productivity. In this study, an attempt was made to improve the homogeneity
of hop fields and restore their productivity by using plant biostimulants as foliar sprays. The
experimental apparatus included four field trials carried out in four plots of different plant vigour, as
evaluated by farmers over previous years (weak, fair, good and very good). The experiments were
arranged as a factorial of foliar treatment (two plant biostimulants containing extracts of seaweed
algae and an untreated control) and year (2017 and 2018). The plot and the year influenced greatly
almost all the measured variables related to tissue nutrient concentration and crop performance. In
the control plots, cone dry matter (DM) yield varied from 83.3 to 394.4 g plant1 from the weak to
the very good plots. In 2018, cone DM yield was significantly higher than in 2017. The use of foliar
sprays influenced less the elemental composition of plant tissue than the plot or the year. The use
of foliar sprays only increased significantly crop yield in the plot of weak plant vigour. The foliar
treatments did not increase - and -acid concentration in the cones; in the control treatment of the
most productive plot, the values were, respectively, 11.2 and 3.9%. Although seaweed extracts tend
to help plants cope with several abiotic and biotic stresses, they showed to be effective in mitigating
the stress that is affecting these plants, which probably is poor soil drainage caused by the flooding
irrigation system, only under conditions of severe stress.
Rendimiento e calidad del lúpulo en respuesta a pulverizaciones foliares ricas en aminoácidos y potássio
Publication . Afonso, Sandra; Arrobas, Margarida; Morais, Jorge Sá; Rodrigues, M.A.
Se evaluó el uso de fertilizantes foliares ricos en aminoácidos y potasio (K) en
un campo comercial de lúpulo en el noreste de Portugal. Se realizaron cuatro
aplicaciones de una aspersión foliar rica en aminoácidos en lugar de una
segunda aplicación de N ao suelo de 70 kg ha-1, generalmente aplicada por el
agricultor. La aspersión foliar rica en K se aplicó una vez en la etapa de desarrollo
del cono como complemento del plan de fertilización del agricultor. La aspersión
foliar enriquecida con aminoácidos mantuvo lo rendimiento del cultivo a los
niveles del tratamiento de control y aumentó la concentración de ácidos alfa
(ácidos α) de los conos (41,8% en 2018 y 9,3% en 2019). El K foliar no aumentó
la producción de materia seca del cono, el tamaño del cono o la concentración
de los compuestos amargos. La concentración de K tisular no se vio afectada
significativamente por los tratamientos foliares, mientras que la aplicación de K
pareció aumentar la absorción de N, siendo las hojas y los tallos los tejidos de
asignación predominantes. Ambos tratamientos foliares aumentaron las
concentraciones de magnesio (Mg) en hojas y tallos. Los resultados parecen
enfatizar la importancia de los aminoácidos en la biosíntesis de los compuestos
amargos, mientras que el K y el zinc (Zn) parecen tener un papel secundario
importante, quizás relacionado con el metabolismo del nitrógeno (N) y su
reducción a aminoácidos. Las concentraciones de fenoles totales en conos y
hojas fueron menores en los tratamientos foliares en comparación con el control,
y los valores más altos se registraron en hojas. En este estudio, el uso de
aminoácidos como aspersión foliar proporcionó un resultado interesante, ya que
mantuvieron el rendimiento del cono y aumentaron la concentración de
compuestos amargos del cono con un uso reducido de N.
The phenolic composition of hops (Humulus lupulus L.) was highly influenced by cultivar and year and little by soil liming or foliar spray rich in nutrients or algae
Publication . Afonso, Sandra; Dias, Maria Inês; Ferreira, Isabel C.F.R.; Arrobas, Margarida; Cunha, Mário; Barros, Lillian; Rodrigues, M.A.
The interest in expanding the production of hops outside the traditional cultivation regions,
mainly motivated by the growth of the craft brewery business, justifies the intensification of studies
into its adaptation to local growing conditions. In this study, four field trials were undertaken on
a twenty-year-old hop garden, over periods of up to three years to assess the effect of important
agro-environmental variation factors on hop phenol and phenolic composition and to establish its
relationship with the elemental composition of hop cones. All the field trials were arranged as
factorial designs exploring the combined effect of: (1) plots of different vigour plants year; (2) plots
of different plant vigor algae- and nutrient-rich foliar sprays year; (3) plot liming year;
and (4) cultivars (Nugget, Cascade, Columbus) year. Total phenols in hops, were significantly
influenced by most of the experimental factors. Foliar spraying and liming were the factors that
least influenced the measured variables. The year had the greatest effect on the accumulation of
total phenols in hop cones in the different trials and may have contributed to interactions that often
occurred between the factors under study. The year average for total phenol concentrations in hop
cones ranged from 11.9 mg g1 to 21.2 mg g1. Significant differences in quantity and composition
of phenolic compounds in hop cones were also found between cultivars. The phenolic compounds
identified were mainly flavonols (quercetin and kaempferol glycosides) and phenolic carboxylic acids
(p-coumaric and caffeic acids).
Hop dry matter yield and cone quality responses to amino acid and potassium-rich foliar spray applications
Publication . Afonso, Sandra; Arrobas, Margarida; Morais, Jorge Sá; Rodrigues, M.A.
The use of amino acid and K-rich foliar sprays was evaluated in a commercial hop field in North-eastern Portugal. Four applications of an amino acid-rich foliar spray were performed in place of a second side dress N application of “70 kg N ha−1, which is usually applied by the farmer. The K-rich foliar spray was applied once at the cone developing stage as a supplement to the farmer’s fertilization plan. The amino acid-enriched foliar spray maintained crop dry matter yield at the levels of the control treatment and increased cone alpha-acids concentration (41.8% in 2018 and 9.3% in 2019). Foliar K did not increase cone dry matter yield, cone size or bitter acid concentration. Tissue K concentration was not significantly affected by foliar treatments whereas the application of K seemed to increase N uptake, with leaves and stems being the predominant allocation tissues. Both foliar treatments increased leaf and stem Mg concentrations. The results seem to emphasize the importance of amino acids in the biosynthesis of bitter acids, while K and Zn seemed to play an important secondary role, maybe related to N metabolism and its reduction into amino acids. The concentrations of total phenols in cones and leaves were lower in the foliar treatments in comparison to the control, and the higher values registered in leaves. In this study, the use of amino acids as a foliar spray provided an interesting result, since they maintained cone dry matter yield and increased cone bitter acid concentration with reduced N use.
Twenty-years of hop irrigation by flooding the inter-row did not cause a gradient along the row in soil properties, plant elemental composition and dry matter yield
Publication . Afonso, Sandra; Arrobas, Margarida; Rodrigues, M.A.
In hops (Humulus lupulus L.), irrigation by flooding the inter-row can carry away suspended
particles and minerals, causing gradients in soil fertility. The effect of more than 20 years of flooding
irrigation on soil and plants was evaluated in two hop fields by measuring soil and plant variables
in multiple points along the rows. In a second experiment 1000 kg ha1 of lime was applied and
incorporated into the soil to assess whether liming could moderate any gradient created by the
irrigation. At different sampling points along the rows, significant differences were recorded in soil
properties, plant elemental composition and dry matter yield, but this was not found to exist over a
continuous gradient. The variations in cone yield were over 50% when different sampling points
were compared. However, this difference cannot be attributed to the effect of irrigation, but rather
to an erratic spatial variation in some of the soil constituents, such as sand, silt and clay. Flooding
irrigation and frequent soil tillage resulted in lower porosity and higher soil bulk density in the
0.0–0.10 m soil layer in comparison to the 0.10–0.20 m layer. In turn, porosity and bulk density were
respectively positively and negatively associated with crop productivity. Thus, irrigation and soil
tillage may have damaged the soil condition but did not create any gradient along the row. The
ridge appeared to provide an important pool of nutrients, probably caused by mass flow due to the
evaporation from it and a regular supply of irrigation water to the inter-row. Liming raised the soil
pH slightly, but had a relevant effect on neither soil nor plants, perhaps because of the small amounts
of lime applied.
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Funders
Funding agency
Fundação para a Ciência e a Tecnologia
Funding programme
POR_NORTE
Funding Award Number
SFRH/BD/116593/2016