Sowing instinct: irradiation of seeds increased wheat yield by a third

Russian scientists have found a way to increase wheat yields by more than 30% without additional chemical treatment. The study showed that pre-sowing irradiation of seeds with low doses of electron and X-ray radiation not only significantly increases grain harvest, but also helps plants to better resist dangerous fungal diseases. At the same time, low radiation exposure does not cause changes in products that are dangerous to humans, experts said. However, if the doses are too high, toxic compounds can form inside the plants. Therefore, it is important not to exceed the thresholds, experts told Izvestia.

Exposure to radiation increased the yield of millet

Specialists from the D.V. Skobeltsyn Research Institute of Nuclear Physics of Moscow State University, the University's Physics and Chemistry faculties, together with the Siberian Federal Research Center for Agrobiotechnology of the Russian Academy of Sciences, studied how pre-sowing treatment of seeds with electrons and X-rays affects plant development. The work combined laboratory experiments, two-year field trials and computer simulations.

Physical methods of seed treatment, including ionizing radiation, are considered as one of the environmentally friendly ways to stimulate crop growth and protect them from diseases, the scientists said.

— We see that with the correct selection of the dose and type of radiation, it is possible to increase the viability of the seed and trigger the adaptive mechanisms of the plant. This is especially important for the agricultural sector, since such technologies potentially allow increasing crop yields and resistance to diseases while reducing the chemical load on soil and plants," said Head of the Laboratory of Radiation Treatment of Biological Objects and Materials at the Department of Nuclear Physics Methods in Medicine and Industry at the D.V. Skobeltsyn Research Institute of Nuclear Physics at Lomonosov Moscow State University., senior lecturer at the Faculty of Physics of Moscow State University Ulyana Bliznyuk.

The object of the study was wheat of the Novosibirsk 29 variety, the seeds of which were treated with accelerated electrons with an energy of 1 MeV and X—ray radiation with an energy of 80 keV (kiloelectronvolt is a unit of measurement for the kinetic energy of particles).

— A field experiment has shown that the effect of pre-sowing treatment cannot be considered separately from the environment. Treatment at the same dose may manifest itself in different ways depending on precipitation, temperature, and phytopathogenic load from the soil. Therefore, in order to implement the technology in practice, it is important to take into account not only the physical parameters of irradiation, but also the agro—climatic context," said Polina Borshchegovskaya, Associate Professor at the Faculty of Physics at Moscow State University.

The dose range of 5-15 G (gray) proved to be the most promising for pre-sowing wheat treatment.

— When searching for the optimal dose range, we relied on experimental data on plant yield and infection with septoria after radiation treatment of seeds with accelerated electrons and X-rays. Already in the first year of field testing, both radiation sources increased yields by 22-48%. In the second year, X—ray radiation demonstrated the most stable positive effect: the yield increase was 9-33%," added Victoria Ipatova, a junior researcher at the Department of Nuclear Physics Methods in Medicine and Industry at the D.V. Skobeltsyn Research Institute of Nuclear Physics at Moscow State University.

The peculiarity of the work was that the scientists did not limit themselves to comparing yield indicators. Using computer simulations, they calculated how the absorbed radiation dose and energy are distributed inside the seed.

The researchers paid special attention to the reactive oxygen species, which are formed when exposed to radiation on water in the tissues of the seed. In large doses, they can damage cells, but in small doses, on the contrary, they trigger protective and adaptive mechanisms. These compounds activate the antioxidant system, help to rebuild metabolism and regulate plant growth, the scientists noted.

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Low radiation doses in agriculture

The practical application of the technology requires not a single "universal" dose, but an individual selection of the radiation regimen. It depends on the type of wheat, the size and shape of the seeds, the type and power of the radiation source, as well as the risk of fungal diseases. Therefore, combining field testing with computer modeling will help you select the most effective processing parameters.

— Further research will be aimed at studying the molecular mechanisms that are triggered in seeds under the influence of low doses of ionizing radiation. Such an integrated approach can become the basis for the development of effective methods for increasing crop yields," said Alexander Chernyaev, Head of the Department of Physics at the Moscow State University Faculty of Physics, Head of the Department of Nuclear Physics Methods in Medicine and Industry at the D.V. Skobeltsyn Research Institute of Nuclear Physics at Moscow State University.

Small doses of radiation can really stimulate the physiological functions of organisms, said Nadezhda Kudryasheva, Professor of the Department of Biophysics at Siberian Federal University, a leading researcher at the Institute of Biophysics of the Siberian Branch of the Russian Academy of Sciences.

— Living systems, trying to compensate for stress, are looking for a new state of equilibrium. And as long as they are able to perform these actions, they are alive. This effect is especially relevant for plants, as they are more resistant to radiation than bacteria or animals," she said.

The expert noted that resistance to radiation directly depends on the complexity of the organism. The more complex it is, the more protective mechanisms it has. Therefore, plants tolerate such effects more easily than bacteria, and are able to respond to it by stimulating physiological processes.

According to Nadezhda Kudryasheva, the key task is to choose the optimal dose. Low levels of radiation do not cause changes in crops that are dangerous to humans, while exceeding them can lead to the formation of toxic compounds. That is why it is necessary to experimentally determine safe and effective modes of technology application for each crop and growing conditions.

Physical methods of seed treatment, including ionizing radiation, are considered a promising way to stimulate their germination, Galina Karpova, Doctor of Agricultural Sciences, Head of the Department of General Biology and Biochemistry at Penza State University, told Izvestia.

— Early stimulation of growth processes can really affect the further development of plants and their productivity. However, the results obtained on the Novosibirsk 29 wheat variety require additional verification. The main question remains open: will it be possible to maintain this effect during the transition from experimental plots to large—scale sowing," she said.

According to the expert, the technology requires further research. It is equally important to evaluate its economic efficiency: it is necessary to find out what production facilities should be in order for their use in the agricultural sector to be profitable. Another task will be to create equipment that can be used on an industrial scale.