PREDICTION OF INFLUENCE OF LOW-LEVEL OF N UTRIENTS ON THE YIELD OF CULTIVARS OF WINTER CEREALS

There is a possibility for preliminary selection of cultivars with goo d nutrient utilisation in laboratory experiments. 1. The stability of root/shoot ratio measured between different nutrient concentrations (1 % and 5%) in nutrient solution is a suitable criterion for prediction of yield stability at a low level of nutrient under field conditions. The degree of change of root/shoot ratio after two weeks of growth in laboratory experiments in 5% and 1% concentration of standard nutrient solution is a very good selection criterion for nutrient utilisation. The larger is the change, the lower is the nutrient utilisation under field conditions (yield of plant biomass and grain). Cultivars with t his type of reaction show small differences between nutrient content a t juvenile plants, but great differences in nutrient content in field conditions. 2. Differences of dry matter of the whole juvenile plants cultivated under two levels of nutrient concentration (5% and 1%) is a good selection criterion for nutrient utilisation at low level of nut rients under field conditions. The lower is the difference, the higher is nutrient utilisation (stability of yield of grain and plant biomas s production). 3. Resistance of cultivars to different abiotic stresse s (drought, high temperature, low pH) are desirable for good utilisati on of low level of nutrients.