Effect of fertilization on water use and yield of hops in mature hop plantation
The effect of decreasing nutrient availability on the ecophysiology and production of hop cones was studied in a plantation of cultivar 'Premiant', in atec hop growing region, Czech Republic. The plantation used to be fertilized by 60 t of manure ha-1 year-1 until November 2011 when it was discontinued as a part of the measures towards organic farming. Measurements of total evapotranspiration from the plantation using the Bowen ratio energy balance method, transpiration of hop bines by the means of sap flow, soil water and nutrient availability were conducted from 2011 to 2014. The yield of hop cones and the content of alpha acids were monitored in this period too. The concentration of total soil nitrogen (N) dropped from 19.4 mg kg-1 in March 2012 to 8.2 mg kg-1 in November 2014. Similarly, the content of N in leaves declined from 4.1% of dry mass in 2012 to 2.5% in 2014. The ratio between total evapotranspiration from the plantation to the potential evapotranspiration (PET) was not affected by the soil nutrient availability and did not vary among the years of study, ranging between average to 91 and 96% of PET. In the contrast to total evapotranspiration and PET, the proportion of hop transpiration on the total evapotranspiration steadily declined from 74 to 46% in 2011 and 2014, respectively. Plant regulation of stomatal conductance changed, bringing along lower stomatal aperture, especially upon the conditions of low vapor pressure deficit. In line with decline in transpiration and stomatal conductance, yield of alpha-acids declined from 204 kg ha-1 in 2011 to 97 kg ha-1 in 2014. To sum up, after the stop in fertilizing, total water use of the plantation remained similar as before, but the transpiration and production of alpha acids ha-1 significantly decreased.
Krofta, K., Kučera, J., Ježek, J., Bednářová, E., Pokorný, J. and Urban, J. (2019). Effect of fertilization on water use and yield of hops in mature hop plantation. Acta Hortic. 1236, 45-52
hop (Humulus lupulus L.), nutrients, evapotranspiration, transpiration, alpha acids