Biometric indices and selenium content in beet and carrot plants using different methods of biofortification with iodine and selenium

The effect of biofortification of carrot (Daucus carota) and beet (Beta vulgaris) plants was investigated using trace elements of iodine and selenium presented as KI and Na₂SeO₃. Biofortification was carried out by two methods: foliar treatment (spraying) with concentrations of 0.005 % and 0.01 %, as well as root application in dosages of 12 and 24 kg/ha for selenium and 6.5 and 13 kg/ha for iodine. Additionally, the combined effects of these micronutrients were studied at concentrations of Na2SeO3 12 kg/ha + KI 6.5 kg/ha and Na2SeO3 24 kg/ha + KI 13 kg/ha for root application, and Na2SeO3 0.005 % + KI 0.005 % and Na2SeO3 0.01 % + KI 0.01 % for foliar spraying. The experimental results showed that the main application of micronutrients had a stimulating effect on the biometric parameters of carrot plants, whereas beet plants showed a depressing effect, especially when iodine was applied. In most variants with foliar processing of beet plants, a decrease in biometric indicators was also noted. The study of selenium accumulation in plants (tops and root crops) revealed a number of specific patterns. In carrots, the maximum selenium content in tops was observed during foliar treatment with a concentration of 0.01 %, where its level exceeded the control level by 31.9 times. Combined application of selenium and iodine (Se + I) also contributed to a significant increase in selenium accumulation in the tops - by 26 times compared with the control. In beets, the highest accumulation of selenium in root crops (12.2 times) and tops (16.2 times) was observed with root application of selenium. In foliar treatment using a combination of Se + I (concentration 0.005 %) the accumulation of selenium in root crops and tops increased by 12.9 and 10 times, respectively, compared with the control variant. At the same time, the selenium content in the dry mass of plants in the control variant did not exceed 0.9 mg/kg in beets and 0.5 mg/kg in carrots. The obtained results demonstrate the differences in the efficiency of biofortification methods for different crops. In contrast to a number of previous studies, where a linear relationship was observed between the dosage of micronutrients and their accumulation in plants, this experiment revealed variable effects depending on the method of application and concentration of micronutrients. To optimize biofortification of plants with iodine and selenium, further studies are needed to clarify the most effective methods and conditions of application.