Raparperin hyötö ja varastointi

Authors

• Kirsti Osara Helsingin yliopiston puutarhatieteen laitos Viik, Helsinki

DOI: https://doi.org/10.23986/afsci.71656

Abstract

Since the forcing of rhubarb is virtually unknown in Finland, experiments with this procedure were carried out in the years 1962—65 using the variety Victoria. The original material had been sown in 1960 so that the plants used in the trials were 3–5 years old. In 1962 and 1963 the rhubarb was stored in cold chambers (—5° C and +1° C) for various lengths of time before forcing. Continuous storage at the same temperature (Table 1) resulted in higher yields and better quality than transfer of the rhubarb during the storage period from —5° to +1° C. Outdoor storage of the plants disclosed that in the cold winter of 1963/64, when the roots were constantly frozen, the yield was better (Table 2) than in the winter of 1964/65, when the temperature varied and the plants alternatingly froze and thawed (Table 4). During the perios of forcing in 1964 some of the plants were daily illuminated between 8 a.m. and 2 p.m. by means of two 80 W »warm white» fluorescent lamps. The illuminated plants gave lower yields than those forced in darkness (Table 2). The stalks of the illuminated plants resembled those grown outdoors and were not as tender and flavourous as those forced in the dark. In 1965 half of the rhubarb plants were liftes together with the surrounding soil block, while the roots of the remaining plants were cleaned of soil. The plants enclosed by the block of soil kept well in outdoor storage and gave a yield twice as great as the soil-free plants (Table 4). Potassium nitrate fertilizer (0.3 % solution) applied at weekly intervals during the forcing period in 1965 had no effect on the yield nor on the colour of the stalks (Table 4), but when given to the plants surrounded by soil it retarded the elongation of the stem. In 1963 and 1964 the forcing temperature was 15° C. In 1965 a temperature of 10° C was employed, which proved to be more advantageous for the colour of the stalks. In the storage trial in 1965 it was established that rhubarb could be kept in a marketable condition for 4 weeks when packed in PV plastic bags and held at a temperature of 1—2° C and a relative humidity of 92 % (Table 5).