hrvatski

Promjenjljivost prinosa ozime pšenice u ovisnosti o vremenskim uvjetima u pojedinim razdobljima porasta

Weather and grain yield of winter wheat (Triticum aestivum L.) data for a 13-year period at two locations, Zagreb-Maksimir (ZGM) in western Croatia and Kutjevo-Ovčare (KUO) in Požega valley, were used to calculate the relation between yield and (1) total precipitation in the wheat season (2) percipitation in the late spring period, May and June and (3) the sum of mean air temperatures above frezzing point in the wheat season. In addition, some extreme weather events in certain periods od plant growth were identified and their effect on yield was estimated using comparisons with literature data. Grain yield data were taken from intensive wheat production on the big farm ŤKutjevoť d.d. and from date and rate field experiments at Maksimir. Only data for the leading cultivar Marija and for optimal seeding data October 10 to 31 were used. On both locations, the soils had good productivity and good to moderate permeability. Grain yield decreased linearly with increasing total precipitation in the wheat season over the range 361 to 815 mm at ZGM and 301 to 694 mm at KUO. With a similar distribution as in average years, total precipitation could be decreased by as much as 200 mm or 40 per cent and yet much above average yields were obtained. However, a great reduction of precipitation to zero or only few mm in October – month of seeding, gave below average yields due to poor emergence and uniformity of emerged plants and reduced stand. On the contrary, heavy precipitation in October, even 150 to 200 mm, 2.5 to 3 times above average, gave no yield decrease, because there were still enough days to perform tillage and seeding operations well in such a moist month. Above average precipitation in the late spring period, when the second part of shooting, flowering, grain formation and filling occured was most detrimental to yield. Increased precipitation in May and June of only 40 to 50 mm above average so that they totally amounted more than 200 in KUO and 220 mm in ZGM, decreased yield below the average. No relation was found between yield and sum of temperatures. In the warmest years during the investigation period in which the sum of tempertures was 2000C and more above the average, above average yields could be obtained if precipitation extremes did not occur. Increased temperature during the winter period, especially in February, even 50C over above the average in this month allows an earlier start of spring growth, which is reflected in increased wheat productivity.

ozima pšenica; oborine; temperature; prinos zrna

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