RESPONSE OF WINTER-WHEAT VARIETIES ON INT ERRELATIONSHIP INFLUENCE OFNITROGEN NUTRITION AND GROWTH RETARDANT APPLICATION

Plant material differed in habitus and mass production. Parameters wer e obtained in experiment conducted with five varieties of winter wheat grown in plastic pots. The plant showed differences in number of leav es, tillers, and leaves on tillers. Differences in ability to synthesi ze and accumulate organic matter were observed by plant organs dry bio mass analysis (Tab. I). The lowest weight of vegetative plant organs w as found for Hela and Selecta varieties. Kosutka variety showed the hi gest plant vegetative organs weights. Plants sprayed with a nitrogen s olution (amonium nitrate, 2.0 mM) in growth phase at the end of tiller ing and with a growth retardant at the beginning of stem elongation we re affected in different way, according to the properties of varieties . Varieties, accumulating organic matters mainly in vegetative organs, are sensitive in suitable growth phase to nitrogen application and fo llowing growth retardant application, and a positive effect was achiev ed for the grain production. Varieties, accumulating a little dry matt ers in vegetative organs (these are preferably distributed into ear st ructures), are less sensitive to the above mentioned type of regulatio ns which do not have a positive influence on the grain production (Tab . II). The vegetative organs of plants were marked for relatively high levels of endogenous gibberellin-like substances. A negative correlat ion in gibberellin-like substances between root and stem was found. Th e treatment of winter wheat plants with growth retardant substance ina ctivated free forms of gibberelins.