Stiinta Agricola (Dec 2020)
Физиологические аспекты ответа соево-ризобиального симбиоза на действие фунгицидов Стандак Топ и Февер
Abstract
The article presents the results of the investigates of physiological aspects of the response of soybeanrhizobium symbiosis (the formation of the symbiotic apparatus and its functional activity, the level and ratio of photosynthetic pigments ‒ chlorophyll and carotenoids in the leaves of plants, the development and productivity of soybean plants) to the seed treatment with fungicides on the day of sowing were studied in pot experiments with soil culture. Methods. Physiological, biochemical, microbiological. Results. It was shown that seed treatment of early-ripening varieties of soybean Almaz with the fungicides Standak Top and Fever on the day of sowing, followed by seed inoculation with nodule bacteria strain 634b significantly inhibited the functioning of the symbiotic apparatus during the budding phase (by 55 and 62%) and full flowering (by 46 and 51%). The realization of the nodulation ability of the microsymbiont remained stable, since the difference in the number and mass of nodules on the plant, the mass of 1 nodule as well as the sensitivity of plants to inoculation (nodulation scale) did not significantly differ against the control (without fungicides) except for the initial phase of symbiosis formation. Under the action of fungicides, an imbalance in the synthesis of green photosynthetic pigments and carotenoids as well as their ratio in the first half of soybean vegetation were established, while these were almost equalized to the level of control plants during the full flowering stage and treated plants had a slightly reduced chlorophyll a content (by 15 and 7%), chlorophyll b (by 10 and 4%) and carotenoids (by 11 and 8%). Compared with Standak Top, Fever had a less toxic effect, and during the developmental stage of three true leaves, it even caused an activating effect on the photosynthetic apparatus of plants: the level of chlorophyll a and carotenoids significantly (5 and 18%, respectively) exceeded the control values. Such changes in the symbiotic and photosynthetic apparatus of soybean plants can be considered as components of the adaptation of soybean-rhizobium symbiosis to the treatment with fungicides and maintenance of proper development of plants in such conditions (positive changes were found in the vegetative mass and growth indicators in the range of 5–21% and 16–39% using Standak Top and Fever, respectively) with stable realization of their productive potential (seed yield at the control level). Conclusions. The physiological aspects of the response of soybean-rhizobium symbiosis to the effect of anthropogenic factor that we have established indicate the possibility of using the fungicides Standak Top and Fever (1.5 and 0.3 l / ton of seeds, respectively) for pre-sowing treatment of soybean seeds on the day of sowing, followed by its rhizobia bacterization.
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