THE SEED GROWING QUALITY AND THE YIELD OF WINTER RAPE IN RELATION TO THE SEED SIZE

In four-year micro-plot trials the effect of seed size on the seed growing quality and the yield of winter rape. The seed of the variety Sonata was calibrated by means of mechanical sieves on four groups: up to 2.0 mm; 2.0 - 2.1 mm; 2.1 - 2.2 mm; above 2.2 mm. The sowing was performed in the trial situated in the beet-growing region by means of the exact small-pot sowing machine OYORD. The sowing rate was calculated on the basis of the germinating ability and thousand-kernel weight (TKW - HTS) of individual fractions of seed in order to keep the standard of 80,000 germinating seeds per 1 hectare. Another cultural practices were governed by current methodology used in the micro-plot trials with rape. The trials were aimed at finding the effect of the seed size on the energy of germination, germinating ability, TKW, and the winter rape yield. Energy of germination and TKW were finding in compliance with the standard CSN 46 0610, vigour after the Hiltner test. The yield was determined by the portion of different fractions in the seed sample. The results published in different years are averaged over three replications. Statistical processing by the method of variance analysis was used solely in the effect of the seed size on the yield. Tab. I presents the resultant values concerning the germinating ability, vigour, TKW and the yield and the values of sowing seed - TKW, sowing rate. Tab. II shows neither one of the parameters of the seed growing quality (energy of germination, germinating ability, vigour) was affected by the seed size. The germinating ability found out in the groups and in individual years was ranging from 99 to 100 %. Energy of germinating ability was lower by 2 %, i.e. ranging from 97 to 98 %. The different values for different years when there was an effect of the year were found in the vigour. In the years 1989 and 1992 the values were remarkably lower (90 to 95 %) than in the year 1990 and 1991 (67 to 95 %). Neither inside the groups any dependence has been found. TKW, as seed growing parameter and paralelly the yield factor, recorded any trends leading to the dependence on the seed size. The TKW level was not affected exclusively by a year. Means for various years were as follows: 1989 - 3.95 g; 1991 - 4.13; 1992 - 4.10 g. A positive effect of the seed calibration on raise of yields per hectare was found, though the dependence was not statistically confirmed (Tab. I and Fig. 1). In the years 1989, 1991 and 1992 there was gained the highest yield in the seed of the size group above 2.2 mm. In 1990 from the seed of the size group 2.1 to 2.2 mm. This size fraction was the second each of three years. It can be said that above-average yields were acquired from the seed above 2.1 mm. The study was dealing with the seed yield from different size groups and the total need for seed for sowing of some area (Tab. II). In the case of use of the seed from two fractions, out of which above-average yields were gained, a larger amount of seed is needed. This was ranging from 18.8 to 42.5 kg.ha-1 at the average sowing rate of 6 kg.ha-1 (in the years under study) what decreases the effect of seed calibration.