Grain yield components of winter wheat new cultivars in correlation with sowing rate

During the process of plant breeding and selection of new winter wheat cult ivars a lot of attention is paid to the improvement of the main components of grain yield-number of ears/m(2), number of grains per ear and 1000 seed weight. Production of cultivars that achieve a large number of fertile ears per unit area, a large number of grains per ear and a heavy 1000 seed weig ht, even with a lower density, would mean that a high grain yield is achiev ed with lower costs. It is of great importance for wheat production in Croa tia. Along with the research on sowing rate influence (400, 500, 600 and 70 0 germinable seeds/m(2)) on winter wheat grain yield, other trials were don e on the grain yield components (number of ears per unit area, number of gr ains per ear and 1000 seed weight) during periods 1996-1997 and 1997-1998 b oth on three AG cultivars of winter wheat Lara, Kruma and Lenta and on the check cultivar Zitarka. The trial was done according to the split-plot meth od in 4 replications. Statistically speaking, various sowing rates had a ve ry significant influence on the number of ears per unit area. The largest n umber was achieved with the sowing rate of 700 germinable seeds/m(2) (783,3 8 ears/m(2)). This number of ears is statistically more significant (P<0,05 ) in relation to the sowing rate of 600 germinable seeds/m2, and statistica lly very significant (P<0,01) in relation to the sowing rates of 400 and 50 0 germinable seeds/m2. On the grounds of the results obtained by a statisti cal analysis it was established that the sowing rate did not have a statist ically significant influence on the other two grain yield components - numb er of grains per ear and 1000 seed weight. The investigated cultivars had a statistically very significant influence (P<0,01) on the number of grains per ear, and a statistically significant influence on 1000 seed weight, whe reas there were no statistically significant differences between the invest igated cultivars in relation to the number of ears per unit area. The large st grain number was achieved with the cultivar Lenta (46,36 grains) and the heaviest 1000 seed weight with the cultivar Lara (45,72 g). The year of re search had a very significant influence on the height of all investigated y ield components in terms of statistics; the first year of research is chara cterized by better results, unlike the second. On the grounds of the obtain ed results it may be concluded that production of the investigated cultivar s with lower density is possible, despite the fact that two out of three ma in yield components were not under influence of the sowing rate.