ABSTRACT 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).

Durante o armazenamento, diferentes espécies comportam-se diferentemente quanto à dormência e crescimento de plântulas. A dormência o desenvolvimento lento das plântulas limitam a época do plantio das gramíneas forrageiras plurianuais. A germinação de sementes e o crescimento das plântulas de azevem italiano (Lolium italicum A. Braun sin. Lolium multiflorum L.), Dactilis (Dactilis glomerata L.) e de timoteo (Phleum pratense L.) foi pesquisada durante a maturação pós-colheita e a silagem. Após a colheita, em junho, sementes foram armazenadas em condições tradicionais e analisadas a cada 30 dias após a colheita, até 270 dias e, em seguida, a cada 60 dias até 990 dias. Nessa pesquisa, avaliou-se a germinação final e o vigor das plântulas. As sementes de timoteo obtiveram germinação máxima (88%) e o melhor crescimento das plântulas após 90 dias de armazenamento, indicando que o melhor período para o plantio das sementes colhidas em junho é o inicio de outono (setembro-outubro). A germinação de sementes de timoteo reduziu nos 270 dias (73%) seguintes. A melhor germinação, e crescimento da plântula do azevem italiano e do dactilis ocorreu entre 270 e 330 dias, indicando que a melhor época para plantio é na primavera (março-abril), do ano seguinte. As sementes de dactilis e azevem italiano mantiveram germinação satisfatória até 630 dias (81%) e 810 dias (81%), respectivamente. Essa pesquisa pode servir para determinação de gerenciamento adequado de duração de armazenamento entre a colheita e o plantio das espécies testadas em condições de armazenamento no sudeste da Europa.

During post-harvest maturation, different species vary in the length of dormancy breaking or germination increases. Seed dormancy and slow seedling development often limit establishment of forage grass stands. Seed germination and seedling vigour of Italian ryegrass (Lolium italicum A. Braun, Synonym Lolium multiflorum L.), cocksfoot (Dactylis glomerata L.) and timothy (Phleum pretense L.) were observed after harvest and storage. After harvest in June, seeds were stored under standard storage conditions and sampled every 30 days after harvest (DAH), up to 270 DAH, and then every 60 days up to 990 DAH. At each date, seeds were tested for final germination percentage and for seedling vigour traits. Timothy seeds had a maximum germination (88%) and the best seedlings vigour at 90 DAH, which implies that early autumn (September-October) is the best sowing period for freshly harvested seeds of timothy. Timothy seed germination was poor from 270 DAH (73%). The best germination and vigour of Italian ryegrass and cocksfoot seedlings were between 270 and 330 DAH, which equates to spring sowing time (March-April) in the succeeding year. Cocksfoot and Italian ryegrass seeds maintained satisfactory germination levels up to 630 DAH (81%) and 810 DAH (81%), respectively. The data can serve for the determination of a proper storage duration management between harvest and sowing of the tested species under ambient conditions of south-eastern Europe.