Abstract
Seasonal changes in carbohydrate and mineral contents of the mature hop plants (Humulus lupulus L.) were investigated. Plant materials sampled were separated into six parts: bines, leaves, cones, rootstocks, roots and storage roots. Measurements of carbohydrate and mineral contents were carried out at eleven main stages of a year. Using the data collected, annual course of carbohydrate economy and mineral economy of the hop plants were discussed. Results obtained were summarized as follows. 1. Carbohydrate content of subterranean parts decreased rapidly in early growing season, reached the minimum in June and July, then increased again before harvest. Since acid hydrolizable polysaccharid was maintained at the constant level of about 5% of dry weight the throughout the year, sugars and starch played important roles in carbohydrate economy. Main component of carbohydrate was Sugar in winter and growing season, and starch in accumulation season. 2. The absorption of K2O was rapid in the early growing season, that of N, CaO and MgO in the middle and that of P2O5 and SiO2 in the late season. At harvest, the ratio of each component for N (N:P2O5:K2O:CaO:MgO) was 1:0.3:1.0:0.8:0.2 in the aerial parts, and 1:0.4:0.8:0.6:0.1 in the subterranean parts. Annual absorption of each component (kg/10a) was N, 11.1, P2O5, 3.3, K2O, 9.7, CaO, 9.6, MgO, O.9 and SiO2, 7.8, respectively. 3. Carbohydrate was translocated from the subterranean parts to the aerial parts in April, May and June, increased in both parts in July and August, and then was translocated from the latter to the former after harvest. On the other hand, mineral components continued to be translocated from the former to the latter until the harvest, after which there was accumulation in the former
