TECHNOLOGICAL QUALITY OF WINTER-WHEAT IN DEPENDENCE ON THE VEAR, SOWING DATE AND SOWING RATE

Results of 16-year study of the effect of year, sowing date and sowing rate on the changes of technological quality of winter wheat are analyzed herein. 54 cultivars and new breeds Triticum aestivum L. were used in experiments in two sowing dates and four sowing rates on some great soil types (loam Luvisol and gleyic Fluvisoil) in soil and climatic conditions of Nitra (South-western Slovakia, maize growing region). For better and clear arrangement, interpretation and practical illustration, the results are presented in the form of diagrams for particular experimental period, i.e. for several-year persisting closed cycles: years 1975 - 1979 (Fig. 1), 1980 -- 1982 (Fig. 2), 1983 - 1985 (Fig. 3), 1986 - 1988 (Fig. 4), 1989 - 1990 (Fig. 5). As documented by Fig. 6, years with warmer and more arid growing season prevailed, thus enhancing the formation of more baking than milling component of the technological quality. Longer action of high air temperature (above 25-degrees-C) at the end of the growing season is very often a main reason for grain yield decline and worser quality of gluten, pointing up the negative relation between its amount and quality in these years (Fig. 3 - 1983, Fig, 4 - 1986). In the years 1979 - 1980 (Fig. 2) and 1984 -1985 (Fig. 3) with more moisture and colder growing season, an intensive growth and better grain development was displayed favourable (at higher temperatures at the end of the growing season) in yields and milling quality (CVM), though the protein content was very low (below 10 %). Ample precipitation to the onset of anthesis and subsequent higher (but not extreme) air temperature without marked fluctuations with low precipitation would be ideal for obtaining high and quality wheat yield. Sufficient amount of precipitation is required in autumn in association with formation of favourable moisture conditions in the soil during stand establishment, facilitating the determination of optimum sowing date and rate. In our conditions of studies of sowing dates - September (third decade) and October (first to second decade), and October date should suit more, probably this is associated with more favourable moisture conditions and with longer time for pre-sowing soil preparation (Fig. 7). Sowing rates tested by us were at the beginning of experiments very high 7, 6, later 5 and 3.5 million germinating seeds per hectare. Technological quality of wheat (without respect to cultivar and site) was better for lower sowing rates. It seems, as referred by K a b r t (1983) that the quality is formed according to the number for spikes and grains to which the taken nutrients are to be splitted. In over-thickened stand the quality is falling, though the sowing rate is increasing for obtaining the high yield. However, the amount of yield only cannot be assessed in efficient use of winter wheat, as in view of the quality of a product, less means often more. Quality wheat provides more valuable materials for processing, whereas this improves the benefit not only for a processor but also for grower due to lower costs for its obtaining.