WEATHER CONDITIONS AND BIOSYNTHETICAL PROCESSES IN HOP CONE

An important influence of weather conditions on bitter substances form ation is generally accepted. Dynamism of alpha bitter acids formation before harvest in the period 1992 to 1996 showed significant year-to-y ear differences. It consisted not only in absolute amount of bitter ac ids, but in composition of hop oils as well. The comparison of meteoro logical data proved some coherence between alpha bitter acids content and extent of temperature and precipitation deviations from long-term average in the period from July to August. The average air temperature s in the range of 16 to 18 degrees C seems to be optimal in Saaz growi ng region from the point of view of bitter acids formation. Increase o f temperatures above this optimum to 20 degrees C can be partly compen sated by higher amount of rain precipitation in split portions or by i rrigation supplied from the ceiling above hop plants (trickle irrigati on). The temperatures above 20 degrees C with the lack of water lead t o the blockage of biosynthetical process.