THE COMPARISON OF SHOOT AND ROOT PRODUCTI ON IN OLD AND NEW CULTIVARSOF WINTER CEREALS

The root and shoot mass of twelve winter wheat cultivars, one of rye a nd one of triticale cultivars were compared in the three-year outside pot trial. The year of selection of wheat genotypes ranged from the st art of the 20th century to the temporary varieties (the year of select ion in brackets): rye - Rapid (1993) and triticale - Dagro (1985); new wheat cultivars - Viginta (1984), Vlada (1990), Hana (1985), Blava (1 992), Pagode (1987), Charkovskaja 90 (1991); older and local cultivars - Bucianska cervenoklasa (1940), Slovenska 200 (1942), Bila od Dukova n (the start of 20th century), Slovenska intenzivna (1949), Kasticka o sinatka (1951), Chlumecka 12 (1907). Rants were grown on two levels of nitrogen fertilization: high rate = 1.7 g N per pot (N2) a low rate = 0.28 g per pot (N1), divided and applied in eight subrates from tille ring to heading. Both treatments had two (1992) or three (1993, 1994) replications. Plants were harvested at the end of anthesis. The result s showed significant intervarietal differences in shoot, root and tota l dry mass and root/shoot ratio of wheat (Fig. 1). The maximum differe nces in shoot and root mass between wheat varieties were on an average of three years 32% and 39% (treatment N2), resp., and 37% and 59% (N1 ), resp. When averaged according to origin, the group of older and loc al varieties showed higher shoot production by 13.3% (N2) and 15.6% (N 1), lower root mass by 8.7% (N2) and 1.3% (N1) and lower root/shoot ra tio than the group of new varieties (Tab. I, Pig. 2). Intravarietal va riability of wheat cultivars, expressed as coefficient of variability, was 8.9% (N2) and 12.3% (NI) in shoot mass, and 16.7% (N2) and 16.1% (N1) in root mass (Tab. II). A good relation of shoot and total plant mass of respective wheat cultivars was observed when compared data fro m pairs of experimental years. The relation of root production and val ues of root/shoot ratio among years were in poor correlation in the pa irs of years. Increasing the dose of nitrogen fertilization from 0.28 g N per pot to 1.7,a N per pot resulted in the enhancement of both sho ot and root growth of winter cereals. The ratio of plant weight under high and low nitrogen fertilization (N2/N1) were in wheats on average in the range of 1.61 to 2.03 (shoots), 1.38 to 2.08 (roots) and 1.62 t o 2.03 (total plant biomass) (Pig. 3). Modern wheat cultivars showed h igher values of the ratio N2/N1 for shoots and roots than older and lo cal ones (Fig. 4). The results obtained are discussed in the context o f the project carried out at Research Institute of Crop Production, Pr aha-Ruzyne, aimed at screening of cereal cultivars with efficient util ization of lower nutrient supply in soil environment.