EFFECT OF PRODUCTION FACTORS ON THE YIELD COMPONENTS OF WINTER-WHEAT

The effect of major production factors (forecrop, fertilisation, irrig ation; soil cultivation and soil preparation) on the yield components and yield of winter wheat was studied in a long-term experiment set up at the Latokep Experimental Nursery of Debrecen University of Agricul tural Sciences. The results of regression analysis and factor analysis led to the following conclusions: In the dry year 1996 peas as forecr op resulted in a 2.5 t/ha yield surplus compared to the less favoruabl e forecrop (maize). After naize as forecrop fertiliser rates up to N-1 50+PK led to a significant increase in the yield of winter wheat, whil e a rate of N-200+PK resulted in a yield decline when combined with wa ter deficiency. After peas as forecrop a fertiliser rate of N-50+PK wa s sufficient under the given experimental conditions to satisfy the fe rtiliser requirements of winter wheat. In 1996 the increase in the win ter wheat yield was caused - in addition to the effect of the NPK fert ilisers applied - primarily by changes in the number of grains per spi ke, the spike length, the spike mass and the number of spikelets per s pike whan the forecrop was maize, and by changes in the number of spik es per unit area, the spike length number of spikelets, and the grain number and grain mass per spike in the case of peas. The yield-increas ing effect of irrigation was manifested as a slight increase in the ge netically determined thousand grain mass when the forecrop was maize.