Hydroponic hop crop (Humulus lupulus L.) under greenhouse conditions in Mexico City
Abstract
H. lupulus is a dioecious plant member of the Cannabaceae family whose female flowers are used in the brewing industry. The value of female plants lies in the lupulin glands that contain resins and essential oils required for the flavor and aroma of beer. Hop crop growths between 35 ° and 55 ° latitude north and south, however, it has been possible to cultivate where conditions does not resemble those observed in the mentioned latitudes. Even more, hop has been hydroponic cultivated in traditional crop areas. Hydroponics provides controlled conditions, isolation and all needed nutrients in an aqueous solution. The aim of this work was to establish a hydroponic hop culture in greenhouse conditions, using a modified Hoagland nutrient solution. An average daily growth rate of 1.17 cm was obtained by rhizome plants and of 1.38 cm for those from freshly germinated seedlings, and an average overall height of 218 cm, an adequate growth when compared to the background of this crop. The data obtained show that hydroponics hop crops can be settle in areas with different conditions from those of the traditional cultivation zone.
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Introduction
H. lupulus is a dioecious plant member of the Cannabaceae family whose female flowers are used in the brewing industry. The cultivated hop, a short day, climbing, herbaceous plant produces new shoots in early spring and senesces to the perennial rootstock in autumn [1]. The value of female plants lies in the lupulin glands that contain resins and essential oils required for the flavor and aroma of beer [2, 3].
Hops are native to the regions of North America, Europe and Asia. It has been used in brewing for hundreds of years, the oldest crop known to date 500 years ago in central Europe [4]. Currently, the main producers are: Germany, the United States and China [5]. One of the most important places for hops cultivation is Hallertau, Germany, which has a Dfb climate (hemiboreal without dry season, mild summer and cold winter), according to the Köppen classification [6], these climatic conditions favor the growth of hops and for that reason, the main producers are areas with similar conditions. Due to the high demand of these flowers, it is now possible to find traditional hop crops in places with different conditions in countries such as Argentina, Chile and Mexico; while hydroponic crops, in addition to the first ones, that were carried out in Armenia, are also commercially developed in Colorado, United States [7, 8, 9, 10, 11, 12, 13].
Like any plant, hops need nutrients from the soil to develop, nitrogen, phosphorus, potassium, calcium, magnesium and sulfur that requires in large quantities (more than 1000 mg/kg of dry matter); and iron, manganese, zinc, boron, molybdenum, nickel, copper and chlorine, which the plant needs in small quantities (less than 100 mg/kg of dry matter) [14, 15, 16]. For the hops plant, the most critical macronutrients are potassium and nitrogen. Regarding micronutrients, hops are negatively impacted considerably by deficiencies of boron and zinc [17]. In the hydroponic culture established in Armenia, the nutrient solution of Davtyan was used: 311 ppm of nitrogen, 65 ppm of phosphorus, 350 ppm of potassium, 150 ppm of calcium and 30 ppm of magnesium as main nutrients [12, 18]. This technique could allow to establish crops in other places where there is a growing demand of high quality and inexpensive hops but the conditions are not favorable, as it is Mexico City [8, 19, 20, 21, 22, 23]. So, the aim of this work was to establish hydroponic hop culture in greenhouse conditions, using a modified Hoagland nutrient solution.
Conclusion
The results of this work support the establishment of hydroponic hop crops in places where conditions are not favorable, such as Mexico City, where there is a growing demand for high quality hops at a reasonable price.