LAUSR

The uniform seed material is a prerequisite of stable yields. Therefore, the aim of the study was to observe variability of physiological seed traits depending on the classification of seeds by size and shape, and to determine advantages of large over small seed fractions. Three maize (Zea mays L.) hybrids (ZP 505, ZP 677, ZP 684), produced in two locations (Orahovo, Plavna), were classified into six fractions; small flat seed (SFS), medium small flat seed (MSFS), large flat seed (LFS), small round seed (SRS), medium small round seed (MSRS) and large round seed (LRS). Two laboratory treatments were applied on seed: TR1 (cold test) and TR2 (20/30 oC). In both temperature treatments, the first evaluation was done after 72-h germination, and then every 24 h until 7th day. The highest total germination (G) was recorded for ZP 677 (93.7%), location Orahovo (94.9%), temperature TR2 (95.2%) and MSFS fraction (89.7%). The total proportion of factors in the variance for G was R2 = 0.694. Locations and genotypes predominantly affected the germination rate (GR), η = 0.338. Flat fraction seeds had more rapid emergence (> 90%) of seedlings than the round fraction seeds (> 85%). Round seeds were more susceptible and seed size had a greater effect on vigour than LRS, 70%. The partial effect of the fraction on G was not estimated (η = 0.037), but its cumulative effect with other factors was evident (Hybrid × Fraction, η = 0.070).