PECULIARITIES OF YIELD FORMATION OF RYE V ARIETIES

The trials with hybrid rye varieties Rapid, Marder and Locarno and cla ssic population of the rye variety Dankovske nove were conducted to st udy the yield formation of the varieties at the different sowing rate (100, 200, 300, 400 and 500 germinating grains per 1 m(2) in hybrid va rieties, and 300, 400 and 500 germinating grains per 1 m(2) in the pop ulation variety), and hence the different density and organization of the stand. At different sowing rate the reduction of the number of pla nts was different and this was rising with increasing density of the s tand. The lowest decline of plants was recorded in thinnest sowing rat es, greatest in highest sowing rates. At different stand density other yield components - number of stems (tillers) and spike productivity - were also formed in a different way. In both experimental years the g reatest number of tillers per plant in hybrid varieties at lowest sowi ng rates 100 and 200 germinating grains per 1 m(2) was found. At the s owing rate of 300 germinating grains per 1 m(2) the number of tillers in hybrid varieties was similar to that of the population variety. Usi ng higher sowing rates (400 and 500 germinating grains per 1 m(2)), ho wever, hybrid varieties responded by a marked decrease in these values . At different sowing rate a different number of bases of future doubl e-flowered spikelets was established what expresses a potential spike productivity. The effect of the law of compensation was again manifest ed when spikes of low potential productivity were established in thick stands in early stages of the growth and development (stage 31 DC and Va stage of organogenesis). The highest yields in the studied set wer e obtained in both experimental years 1995 and 1996 by hybrid varietie s at sowing rates of 200 and 300 germinative grains per 1 m(2). When h igher sowing rates were used (400 and 500 germinative grains per 1 m(2 )), hybrid varieties responded by statistically significant decrease o f yields. In the variety Dankovske nove the sowing rate of 400 germina tive grains per 1 m(2) seemed to be the best in both years, the differ ences in yields among different sowing rates 300, 400 and 500 germinat ive grains per 1 m(2) were statistically insignificant. This indicates greater sensitivity of rye hybrid varieties to over-density of the st and and lower autoregulation capacity when compared with the tradition al population varieties. The structure of the yield indicated that the principle of higher yield capacity of rye hybrid varieties compared w ith population varieties consists as in higher and more productive til lering, as in higher spike productivity. In optimum sowing rates for h ybrid varieties (200 to 300 germinative grains per 1 m(2)) an average number of grains per spike in them ranged around 60 in 1995 and around 58 in 1996. This resulted in high values of the number of grains per area unit at relatively good level of caryopsis weight. Increased numb er of grains per spike was allowed in hybrid varieties by greater assi milation area per one established spikelet. In the population variety Dankovske nove average number of grains per spike was significantly lo wer - at the sowing rate of 400 germinative grains per 1 m(2) in which this variety reached highest yields in both experimental years, this was even 49 grains in 1995 and 44 grains in 1996.