ABSTRACT The environment protection, energy, and resources preservation are especially pronounced under present climate changes. In agriculture, these changes are recognised as drought, high temperatures, occurrence of stormy winds and hail. The aim of this study was to determine variations in seed morphology that are a result of different sowing dates in relation with agro- ecological conditions of maize (Zea mays L.) cultivation. The material used for the study encompassed three inbred lines (G1, G2, G3) sown every 10 d on five sowing dates (T1, T2, T3, T4, T5) starting from 1 April to 10 May, during 2 yr (Y1: 2018, Y2: 2019). The following physical properties of seeds were estimated: width (W), length (L), thickness (Tk), ratio of small (SF) to large fraction (LF) and grain yield (GY). The width was the highest in all three inbreeds on T4 (1.00, 1.03, 0.99 cm, respectively); T5 was the least favourable date for L (1.09, 1.12, 1.09 cm, respectively) while Tk was the lowest in G1 (0.51 cm) and G2 (0.51 cm) sown on T1. The most significant differences in the formation of physical properties occurred in seeds sown on T5 (p ≤ 0.05). The highest differences were observed in width between T5-T4 (-0.223 cm), in length between T5-T2 (-0.309 cm) and in thickness between T5-T3 (-0.129 cm). Later sowing dates favoured LF (85.2%) in comparison to SF (14.7%). Seed size variability participated with 50% in yield formation (R2 ≥ 0.5).

O objetivo deste trabalho foi determinar se e em qual estágio de maturidade fisiológica das sementes o dessecante diquat afeta a produtividade e a qualidade de sementes de aveia-perene (Arrhenatherum elatius), bem como o período de armazenamento adequado entre colheita e semeadura. O dessecante diquat foi avaliado em aplicações nos estágios de leite ou de cera do amadurecimento de sementes. Sementes produzidas convencionalmente e armazenadas em condições tradicionais foram utilizadas para as análises. Amostras de sementes foram coletadas a cada 30 dias após a colheita (DAC). Após o 240º DAC, as amostras foram retiradas a cada 90 dias até o 690º DAC. A maior produtividade, com qualidade satisfatória da semente, foi obtida pela dessecação aplicada no início da fase de cera. A germinação final e os parâmetros de crescimento das plântulas alcançaram valores máximos entre 180 e 240 dias após a colheita. As sementes de aveia-perene mantiveram germinação final satisfatória (75%) até 420 dias após a colheita. A dessecação com diquat, na fase inicial do estágio de cera do amadurecimento das sementes, pode ser uma boa solução para a produção de sementes de aveia perene. O início da primavera é o melhor período para plantio de sementes recém-colhidas de aveia-perene, em termos de germinação e crescimento de plântulas.

The objectives of this work were to determine whether and at which seed physiological maturity stage the diquat desiccant affects the tall oat-grass (Arrhenatherum elatius) seed quality and yield, as well as the proper storage period between harvest and sowing. Diquat desiccation was evaluated in applications during milk or dough seed maturation stages. Seeds conventionally produced and stored under traditional storage conditions were used for the analyses. Seed samples were drawn every 30th day after harvest (DAH). After the 240th DAH, samples were drawn every 90th day up the to 690th DAH. The highest yield were obtained by desiccation applied at the beginning of the seed dough stage, with a satisfactory seed quality. Both final germination and seedling growth parameters achieved their maximum values between 180th and 240th DAH. Oat-grass seeds preserved satisfactory level of final germination (75%) up to 420th DAH. The application of diquat desiccant at the beginning of seed dough maturity stage can be a good solution for seed production of tall oat-grass. Early spring is the best sowing period for freshly harvested seeds of tall oat-grass regarding germination and seedling growth.