The influence of fungicidal protection on the formation of photosynthetic parameters of soybean crops

Abstract

The purpose of the research was to determine the effect of fungicidal protection on the formation of the leaf surface area and photosynthetic indicators of soybean crops. The research was conducted in 2021– 2023 in the conditions of LLC «Savarske» Obukhiv district Kyiv region. The scheme of the experiment: Factor A. Varieties «Amadea», «Aurelina». Factor B. Fungicides. Control (treatment of seeds and plants with water), «Maxim Advance 195 FS» (1.25 l/t) (treatment of seeds before sowing), «Vibrance RFC» (1 l/t) (seed treatment before sowing), «Selest top 312.5 FS» (1 l/t) (seed treatment before sowing), «Standak Top» (2 l/t) (seed treatment before sowing), «Abacus» (2 l/ha) (during the growing season), «Maxim Advance 195 FS» (1.25 l/t) + «Abacus» (2 l/ha), «Vibrance RFC» (1 l/t) +»Abacus» (2 l/ha), «Selest top 312.5 FS» (1 l/t) + «Abacus» (2 l/ha), «Standak Top» (2 l/t) + «Abacus» (2 l/ha). The maximum indicators of the leaf surface area of soybean plants of the varieties «Aurelina» and «Amadea» were obtained in the phase of grain formation – 44.85 and 45.91 thousand m2 /ha. The smallest assimilation surface of crops was in the budding phase – 15.10 and 15.07 thousand m2 /ha. Under the influence of fungicidal protection the leaf surface area of varieties «Amadea» and «Aurelina» increased by 0.90 and 0.94 thousand m2 /ha in the flowering phase and by 3.11 and 3.46 thousand m2 /ha in the phase of grain formation, compared to control variants. The greatest increase in leaf surface area was noted for the combined use of fungicides «Standak Top» (2 l/t) for pre-sowing seed treatment and «Abacus» (2 l/ha) during the growing season. According to the results of dispersion analysis varietal characteristics (37.7 %) and fungicidal protection (35.4 %) had the greatest influence on the formation of the leaf surface area of soybean plants and the interaction of these factors was 12.3 %. The highest photosynthetic potential of the varieties «Amadea» and «Aurelina» was on the variants of fungicides application «Standak Top» (2 l/t) + «Abacus» (2 l/ha) – 3.09 and 3.16 million m2 × days/ha, «Selest top» (1 l/ t) + «Abacus» (2 l/ha) – 3.08 and 3.14 million m2 × days/ha and «Vibrance» (1 l/t) + «Abacus» (2 l/ha) – 3.06 and 3.13 million m2 × days/ha. The maximum values of the net productivity of photosynthesis in the varieties «Amadea» and «Aurelina» were obtained in the budding phase – 3.88–4.16 and 3.89–4.27 g/m2 × day. The use of fungicidal protection provided an increase of this indicator by 0.07–0.28 and 0.06– 0.38 g/m2 × day, compared to the control options. Depending on the accounting periods, the variety «Aurelina» was superior to the variety «Amadea» in leaf surface area by 1.6–3.8 % in photosynthetic potential by 1.2–2.5 % and in net photosynthetic productivity by 0.8–1.7 %. Key words: soybean, varieties, fungicides, crop protection, leaf surface area, photosynthetic potential, net photosynthetic productivity.