Effect of Testosterone, Dihydrotestosterone, Estradiol and Cortisol on the Quality of Fresh and Cryopreserved Stallion Sperm

The effect of steroid hormones on the quality of fresh and cryopreserve sperm has not been fully understood. This study aimed to evaluate the effect of testosterone, dihydrotestosterone, estradiol, and cortisol on the quality of fresh and cryopreserved stallion sperm. The study was conducted on 40 Equus caballus stallions, including Arab (n=20), Oryol trotting (n=4), Standardbred (n=4), and Soviet Heavy Draft (n=12) breeds. The average age of the experimental animals was 9.9 ± 0.7 years. We determined standard quality indicators in fresh and cryopreserved sperm and the concentration of steroid hormones in the blood plasma of stallions. Results of the study suggested a negative correlation between the level of testosterone with total (r=-0.41; p<0.01) and progressive (r=-0.44; p<0.01) sperm motility in cryopreserved sperm as well as in fresh sperm (r=-0.38; p<0.05 and r=-0.39; p<0.05 correspondingly). While the level of estradiol showed a positive correlation with survival rate in cryopreserved (r=0.35; p<0.05) and in fresh (r=0.33; p<0.05) sperm. Further, the level of cortisol in the blood plasma of stallions did not show any statistically significant correlations with the qualitative characteristics of sperm.  A positive relationship was found between the concentration of dihydrotestosterone with the volume of ejaculate (r=0.37; p<0.05) and the total number of sperm in the ejaculate (r=0.43; p<0.01). Results of the study can be concluded that steroid hormones have different effects on the quality indicators of fresh and cryopreserved sperm of stallions and their concentration in the blood should be considered when selecting stallions for cryopreservation of sperm

Exogenous regulation of the potatoes’ adaptive potential when using bio stimulants

Potato from the Solanaceae family is one of the most important crops in the world and its cultivation is common in many places. The average yield of this crop is 20 Mg·ha-1 and it is compatible with climatic conditions in many parts of the world. The experiment studied the possibility of exogenous regulation of the adaptive potential available for four potato cultivars through the use of growth stimulants with different action mechanisms: 24-epibrassinolide (EBL) and chitosan biopolymer (CHT). The results allowed us to establish significant differences in growth parameters, plant height, leaf index, vegetation index, chlorophyll content, and yield structure. Monitoring growth and predicting yields well before harvest are essential to effectively managing potato productivity. Studies have confirmed the empirical relationship between the normalised difference vegetation index (NDVI) and N-tester vegetation index data at various stages of potato growth with yield data. Statistical linear regression models were used to develop an empirical relationship between the NDVI and N-tester data and yield at different stages of crop growth. The equations have a maximum determination coefficient (R2) of 0.63 for the N-tester and 0.74 for the NDVI during the flowering phase (BBCH1 65). NDVI and N-tester vegetation index positively correlated with yield data at all growth stages