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 7 th 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 R 2 = 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).

The International Seed Testing Association (ISTA) was established in 1924 with the idea of standardization in seed testing worldwide. The first international rules for seed testing (ISTA Rules) were published in 1931. The development of ISTA Rules is constant. ISTA members are involved in the ongoing process of developing methods for seed sampling and testing. The methods are validated to ensure that test procedures provide reliable and reproducible results. Since 2001, ISTA Rules have been issued annually. ISTA accredited laboratories have to work according to valid ISTA Rules. In this paper, ISTA Rules changes in seed germination testing since 2001 were presented. Changes in testing methods, criteria for seedling evaluation, procedure of calculation and reporting of results are presented in detail. It can be concluded that the amendments to the ISTA Rules are necessary in order to harmonize seed testing and modern trends in seed trade.

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The present paper shows results obtained on effects of priming of sunflower seeds, subjected to accelerated ageing and the cold test, on seed vigour. Seeds were primed with distilled water, the potassium nitrate solution (0.2%) and the gibberellic acid solution (0.04%). The following parameters were tested: energy of germination, germination, proportion of abnormal seedlings, lengths of roots and shoots of normal seedlings. Accelerated ageing in the course of 3 and 5 days resulted in a statistically significant reduction in energy of germination and germination; it adversely affected the length of roots and shoots and it increased the proportion of abnormal seedlings. Seed priming with all three solutions mitigated adverse effects of 3-day accelerated ageing on energy of germination. Furthermore, seed priming with gibberellic acid prior to 3-day accelerated ageing positively affected seed germination and neutralized a negative effect of accelerated ageing on the number of abnormal seedlings, as well as on lengths of shoots and roots of normal seedlings. The cold test (at 5°C for 7 days) negatively affected energy of germination and the root length, increased the proportion of abnormal seedlings and did not affect seed germination. Priming of seeds with distilled water prior to the cold test completely neutralized the adverse effect of low temperatures on energy of germination. Finally, priming of seeds with all three solutions completely neutralized the adverse effect of cold test on the root length.

The purpose of this paper is to evaluate the effect of the year of cultivation, seed population and mycorrhizal seed treatment on two most important indicators of the pepper seed quality, namely germination energy and total germination. The pepper seed quality parameters, i.e. the first count and the total germination rate, were examined in the period 2017-2018. The results obtained show significant differences (p < 0.01) between the parameter values under consideration relative to the year of cultivation (Factor A), seed population (Factor B) and mycorrhizal sees treatment (Factor C). In the first experimental year, there was an increase in the first count and total germination of 4 to 6 % compared to the control when pepper seeds were treated with the mycorrhizal formulation. In the second experimental year, an increase in the first count was in the range of 3 to 16 %, whereas an increase in the total germination was 3 to 4 %, compared to the control. The effect of mycorrhizal pepper seed treatment proved beneficial especially to aged seeds that were slow to germinate.

Early maize sowing enables longer growing season with enhanced possibility of achieving higher and more stable yields, and better chances of avoiding summer droughts. For early sowing, cold-tolerant maize genotypes should be used. Breeding maize, tolerant to low temperatures, requires knowledge of genetic diversity and heterotic patterns of breeding material. The objective of this study was to determine genetic diversity of 15 ZP maize inbred lines applying the method of protein markers (UTLIEF method), and to establish correspondence between thus obtained classification with the results of cold test (CT) and field emergence (FE). During two production seasons (2011 and 2014), 15 maize inbred lines were self-pollinated. Pedigree data showed that material belongs to different maturity and heterotic groups. Cold tolerance was assessed in laboratory (2015) by cold test (7.5 °C, 10 days), and field trials on two locations during two successive years (2015, 2016). ZP maize inbred lines showed very good response to stressful conditions of CT and FE. Inbred lines with Lancaster background were more sensitive to low temperatures than inbred lines with BSSS and Iowa Dent background. Based on UTLIEF method two inbred lines with Lancaster background (ZPL 5 and ZPL 7) were grouped by cluster analysis together with Iowa Dent inbred lines, that also expressed better cold tolerance, and thus exceptional consent was achieved with the results of CT and FE. Classification of maize inbred lines based on UTLIEF method, followed by cluster analysis and PCA, showed good agreement with pedigree data, which points out that this method could be successfully applied for genetic classification of breeding material of a wide genetic background.

The purpose of this study was to determine changes of lipoxygenase activities, contents of antioxidants (tocopherol α, β-carotene and chlorophyll) fatty acids and soluble proteins, as well as, vigor in accelerated aged soybean seeds. The following soybean cultivars were used in the study: Williams 82, Goyou Kurakake and L93-7290. Subsequent to the accelerated ageing test (AAT), 23% of seeds of the cultivar Goyou Kurakake retained normal germination, while grain of the two remaining cultivars L93-7290 and Williams 82, completely lost germination ability. According to our results, the seeds of the cultivar Goyou Kurakake (the absence of lipoxygenases 2) is characterized by a significantly higher content of all observed antioxidants (tocopherol α 2.7 mg 100g-1, β-carotene 6.1 µg g-1 chlorophyll 4.9 µg g-1). The contents of (β-carotene and chlorophyll decreased after AAT in the seed of the cultivar Goyou Kurakake by 42.8% and 60.5%, respectively, while the content of tocopherol a remained the same. Furthermore, the tocopherol a content was not changed after AAT neither in the cultivar L93-7290 nor in the cultivar Williams 82. The content of β-carotene after AAT remained the same in seeds of the cultivar Williams 82 while it decreased by 7.7% in the cultivar L93-7290. Since changes of the fatty acids content were not pronounced in the cultivar Goyou Kurakake after AAT it can be concluded that the antioxidative system had a crucial role in seeds protection against lipid peroxidation

One of the strategies for overcoming global climate change threatening to decrease maize yield is early sowing. To contribute to the development of cold‐tolerant hybrids this research focused on the genetic background's comparative analysis in maize inbreds with good combining ability. Leaf whole‐transcriptome sequencing of 46 maize genotypes revealed 77 differentially expressed genes (DEGs) between Lancaster and other heterotic groups (i.e. BSSS, Iowa dent, Ohio), referred to as non‐Lancaster group, under optimal growing conditions. Cold test of the subset of four Lancaster and four non‐Lancaster lines showed that the former were cold sensitive and the latter cold tolerant. Cold‐induced expression analysis of seven DEGs in eight lines revealed different expression regulation dependent on the duration of cold exposure and genetic background for six out of seven analysed genes—chloroplast ATP‐sulphurylase, photosystem II cytochrome b559 alpha subunit, CIPK serine‐threonine protein kinase 15, glutamyl‐tRNA reductase, photosystem II reaction centre protein I and Calvin cycle CP12‐chloroplastic‐like encoding genes. The results imply that differently regulated basic processes between Lancaster and non‐Lancaster maize group involve, at least, photosynthesis and sulphate assimilation, contributing to their different cold response and different adaptation to low temperatures.