The study of bioactive compounds and gross β-radioactivity of some grain vegetables and medicinal plants in outdoor hydroponic systems and soil culture in Ararat Valley

Abstract

Background: In the 21st century, nuclear reactors pose a significant threat to humanity. During operation, they release both natural (40K, 234Th, 232Th, etc.) and technogenic (137Cs, 90Sr, 89Sr, etc.) radionuclides (RN) into the biosphere, which can negatively affect human health. These RN enter agroecosystems through various transfer pathways. In hydroponics, the RN enters agroecosystems through a nutrient solution, then through the substrates, and finally through the plant. In soil, RN enters agroecosystems through irrigation from water to the soil and eventually to the plant. Through air basins, RN can also infiltrate hydroponic and soil-grown plants. Consequently, the accumulation of RN in plants poses health risks when consumed. Therefore, monitoring β-emitting RN in agricultural crops and medicinal plants is crucial to ensuring radio-safe plant materials.

Objective: This study aims to identify the optimal conditions for cultivating plants with a high content of bioactive compounds (BC), that are radioecologically safe. We investigated the β-emitting RN and BC content in various grain crop varieties, including lentil (Talini 6 – aboriginal, Flip 2007 3L – introduced from ICARDA), corn, chickpeas (Anush, Karin – aboriginal, Flip-07-44B – introduced from ICARDA), soybean (Menua – aboriginal), and medicinal plants introduced to Armenia: Echinacea (E.) purpurea (L.) Moench and Lavandula (L.) angustifolia Mill. These plants were grown in different hydroponic systems, including classical, water-stream, drip, and soil culture. The research was conducted at the Hydroponics Experimental Station, located 30 km from the Armenian Nuclear Power Plant (ANPP). Based on our findings, we have developed practical recommendations to ensure the production of radioecologically safe plant material.

Methods: Total protein content was determined using the Kjeldahl method. Gross β-radioactivity level in plant samples was measured using UMF-1500 equipment.

Results: Protein content ranged from 9.7 to 31.5% in hydroponically grown grain crops and from 11.7 to 24.0% in soil-grown crops. Based on protein content, hydroponically grown crops ranked as follows: soybean>lentil (Flip 2007 3L)>lentil (Talini 6)>chickpea (Flip 07-44B)>chickpea (Karin)>corn. In soil-grown plants, the ranking differed: lentil (Flip 2007 3L)>soybean>lentil (Talini 6)>chickpea (Flip 07-44B)>chickpea (Karin)>corn. Gross β-radioactivity in classical hydroponic system grown grain crops ranged from 70-400 becquerels per kilogram (Bq/kg), while soil-grown grain crops exhibited radioactivity levels between 50-410 Bq/kg. Medicinal plants showed gross β-radioactivity values between 400-550 Bq/kg (hydroponically) and 260-370 Bq/kg (soil). The ranking for hydroponically grown crops based on gross β-radioactivity in their edible parts was as follows: soybean>chickpea (Anush)>chickpea (Karin)>chickpea (Flip 07-44B)>lentil (Talini 6)>lentil (Flip 2007 3L)>corn. For medicinal plants, the order was as follows: E. purpurea>L. angustifolia.

Novelty: For the first time in the Ararat Valley, optimal cultivation conditions for radio-safe crops and medicinal plants rich in BC (proteins, polysaccharides, phenols, essential oils, etc.) have been identified within a 30 km radius of the ANPP. These plants can be utilized for medicine and as ingredients for functional foods.

Conclusion: Both indigenous and introduced crops, along with medicinal plants cultivated under various hydroponic and soil conditions in the IHP (Institute of Hydroponics Problems) area of the Ararat Valley, have been confirmed as radioecologically safe and rich in BC. Their gross β-radioactivity did not exceed 1.0 Bq/g, confirming their suitability for consumption according to WHO guidelines.

Keywords: protein, essential oil, flavonoids, polysaccharides, fatty acids, radionuclides, radio-ecological safety.