Accumulation of energy by non-irrigated and irrigated hop plants (Humulus lupulus L.)

In the conditions of Krusne hory rain shadow hop plants irrigation has a gr eat importance for economic effectivity of hop growing. The shortage of wat er negatively influences the course of physiological processes, such as the growth and photosynthesis. Accumulation of energy matters is affected by t his and finally also the yield formation. Accumulation of energy in hop pla nt is of a dynamic character in the course of vegetation. Maximum energy pe r unit of dry matter in hop plants is concentrated in the first half of veg etation and in the following period of vegetation the net energy was decrea sing. By the non-irrigated variant it was 16.71 kJ.g(-1) (1997) and 16.50 k J.g(-1) (1998). By the irrigated variant it was 15.59 kJ.g(-1) (1997) and 1 6.32 kJ.g(-1) (1998) (Figs. 1 and 2). Comparing both of the experimental va riants shows that differences in net energy accumulation per 1 g of dry mat ter between non-irrigated and irrigated variant are statistically non-concl usive. Yet we can state that non-irrigated plants of precipitation do not f ully utilise rich in energy matter, what results in higher values of net en ergy per 1 g of dry matter. Maximum of energy in individual organs was conc entrated into the period of their intensive growth and in the following per iod of vegetation net energy in these organs was decreasing, except the hop cone by which the increase of energy content occurs during the pre-harvest period. Accumulation of net energy in hop cone could be explained by trans porting of assimilates from leaves into underground organs. Comparing indiv idual organs most of net energy per 1 g of dry matter was in leaves, from 1 6.80 to 17.77 kJ.g(-1) (Tabs. IV and V). Among the experimental years 1997 and 1998 conclusive differences were In the accumulated energy amount what results in the fact, that energy in hop plants is accumulated in dependence on the year (Golley, 1961; Hnilicka, 1996; Hnilicka, 1999; Fuksa et al., 1 999).