Field experiments were conducted with two winter wheat cultivars that were primed with 6-benzylaminopurine (6-BA) or kinetin at the concentration 10 mg/L twice during the grain filling stage. After priming, wheat physiological parameters were measured in the field, and the analysis of yield was performed after harvest. Harvested seeds were subjected to low temperature storage for 12 months at –18 °С simulating conservation conditions in genebanks. In field experiments, treated plants exhibited up to 14% higher productivity, higher fresh and dry weight, and chlorophyll content index of flag leaves. Priming significantly improved germination, seedling vigour and growth parameters. In 5-days-old seedlings developed from low temperature stored seeds of field primed plants, the average accumulation of malondialdehyde and H₂O₂ was estimated 25% lower, which contributed to higher cell membrane stability. These results correlated positively with growth characteristics of 15-days-old seedlings. The stimulating action of cytokinin priming was more pronounced in the modern cv. Geya-1 compared to the older cv. Sadovo 772 and could be attributed to improved anti-aging mechanism connected with better protection against oxidative damage.

Maize (Zea mays L.) plants were treated with synthetic cytokinins -6-benzylaminopurine (BAP) and 6furfurylaminopurine, or kinetin (KIN) -during the grain filling stage in a field experiment performed in 2020 in Sadovo, central Bulgaria. The objective was to study their effect on plant productivity and seedling viability of maize after cold storage. The morpho-physiological parameters of the leaves assessed 15 days after cytokinin priming showed an increase in biosynthetic processes compared to control plants. Analysis of yield parameters at harvesting revealed improved productivity of cytokinin-treated plants, which was evidenced as 10 mg L −1 KIN, and BAP priming resulted in, respectively, 18% and 16% higher grain mass compared to untreated plants (control). The produced seeds were exposed to cold storage (−18°C) for 12 months and afterwards physiological parameters of 5-day-old seedlings were measured to evaluate exogenous cytokinins' impact upon stress alleviation. The seedlings developed from cytokinin-treated plants accumulated significantly lower amounts of oxidative stress markers (hydrogen peroxide and malondialdehyde) after cold storage. In a laboratory experiment, maize seeds were subjected to artificially induced senescence (AIS) test for 72 h at 41°C temperature and were subsequently soaked in cytokinin solutions. Cytokinins had a positive effect on both physiological parameters of seedlings of field-grown plants after cold storage and improved the performance of seedlings after AIS test through increased oxidative stress protection and enhanced reactive oxygen species (ROS) detoxification.

Seeds from the maize /Zea mays L./ variety Kneja 310 and landrace B0E0170 were subjected to controlled accelerated aging test (AA) for 72 hours and 120 hours at temperature 41±0.5°C and 100.0% air relative humidity. For the control variant, not subjected to the АА test seeds were used. After AA test, all seed variants were germinated and were used for an analysis of germination energy. The emerging coleoptiles were studied for the presence of anti-oxidative response (MDA, hydrogen peroxide, cell membrane stability), and morphological parameters and relative chlorophyll content were assessed as well as. A vegetation pot experiment was performed with the AA-72h variant and 15-day seedlings were morphologically and physiologically assessed. The aim of the study was to evaluate the relationship between the vitality of the seeds and their stress response to the controlled AA test, which simulated low-temperature storage. The germination rate of seeds and the fresh and dry weight of coleoptiles following ageing treatments were decreased. These results correlated well with the increased accumulation of total hydrogen peroxide and MDA content and the decrease of cell membrane stability. Negative changes were observed in chlorophyll content index, fresh and dry weight and leaf area of 15-day seedlings in pot trial. It was concluded that the controlled accelerated ageing could be used as a model for estimation of seed deterioration in maize after long-term storage.