Hop (Humulus lupulus L.): Suitability of Traditional Cultivars to a Low-Trellis Farming System in a Semiarid Environment

Abstract

Humulus lupulus is a dioecious twining herb, with an outstanding vertical development capacity. Hop plants are usually grown on trellises up to 4.5 to 6.0 m high, whose management requires intense use of water, fertilizers, pesticides, and labor. In semiarid Mediterranean areas, where native resources are often scarce, the adoption of low-trellis farming systems could be a sustainable option for hop cultivation. With the aim of evaluating hop suitability to low-trellis cultivation in a Mediterranean environment, in 2018 and 2019 three traditional hop genotypes (‘Cascade’, ‘Chinook’, and ‘Nugget’) were grown, and their development rate was evaluated and put in relation with the plants’ cone, root, and biomass yield. Moreover, organic (fragmented pine bark) and synthetic [black polyethylene (PE) plastic film] mulches were applied on the same cultivars, and both epigeal and hypogeal development were evaluated. The results showed that the faster the growth in the first two phases of plant elongation (up to 50% of the height of the upper wire), the lower the yield in both cones and total epigeal biomass. A fast growth rate was instead associated with a higher hypogeal biomass production. Mulching was able to significantly affect the hypogeal biomass, specifically for cv. Cascade, where the use of synthetic mulching allowed significant root biomass increases. The analysis of the results obtained showed that hop’s suitability to a low-trellis farming system is highly variable among varieties in the semiarid Mediterranean environment.

Adapting American Hop (Humulus lupulus L.) Varieties to Mediterranean Sustainable Agriculture: A Trellis Height Exploration

“…These initial outcomes, derived from this 2-year trial, affirm the suitability of Cascade for cultivation in semi-arid environments. Additionally, hop appears well-suited for lowtrellis farming in Mediterranean climates, and this is consistent with the findings of several recent studies [12,13,15]. It is not in doubt that further investigations into other varieties or management systems could significantly contribute to improving our understanding of hop species behavior in new cultural areas, such as the regions of southern Italy.…”

“…For the experiment, two American hop varieties that had already proven good adaptability to Mediterranean environments with semi-arid climates [9,12], i.e., Cascade and Chinook, were selected. The variety Cascade, developed in the USDA breeding program at Oregon State University and released in 1972, is characterized by a dark green elongated cone with a medium-strength aroma, often described as a distinctive floral, grapefruit-like character [24].…”

“…This movement has triggered intensive research focusing on the adaptability of hops species to different cultivation environments in the peninsula [5][6][7][8][9][10][11]. Indeed, several studies conducted in Mediterranean climate environments have highlighted the excellent adaptability of various American varieties, both in terms of production [12][13][14] and quality (i.e., content in alpha acids and aromatic oils) [15][16][17]. This suggests that the Italian hop industry would have nothing to envy about other production markets abroad.…”

“…To our knowledge, no research has investigated, so far, the open-field productivity of hops under typical Mediterranean climates when employing low-trellis systems. Several studies have demonstrated that lowheight systems offer benefits in terms of sustainability and environmental protection [12,18]. Besides requiring lower technical inputs (such as water and fertilizers), they are also less demanding in terms of crop management and initial expenses.…”

Resilience of hop (Humulus lupulus L.) to salinity, heat and drought stresses: A mini-review

“…Hence, a definite compositional and aroma difference was assessed between hops grown in the coastal areas and others from inner Corsica; although salinity could not be claimed as the only cause of these variations, it was certainly involved in the combined co-presence of the high salinity of soils, water scarcity, and wind, acting as a multiple stressor on cultivated plants. Interestingly, it appeared that not all the varieties reacted in the same way, as they have not been directly improved for salinity resistance, showing also very important information for growers to make a proper choice of hop cultivars that suit better to the local growing conditions, and that would be consistent with the outcomes of a recent research carried out in a semi-arid Mediterranean environment ( Carrubba et al., 2022 ).…”