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Phytostimulator Application after Cold Stress for Better Maize (Zea mays L.) Plant Recovery
Phytostimulators are attracting considerable attention for replacing mineral fertilizers, which are of environmental concern, being especially forbidden in organic farming. The benefit of applying such products based on microorganisms (e.g., algae extract) or minerals of nano-meter-sized particle (e.g., nanofertilizers) is that plants can uptake them faster than soil fertilizers, targeting plant growth by regulating their phytohormones, as well as improving plant tolerance to unfavorable environmental conditions (e.g., cold stress). The aim of this study was to test and evaluate the effects of three commercial phytostimulators, called biostimulants (a seaweed-based extract—Kelpak®, mineral nanoparticles—Nano Active®, zinc nanoparticles—Dynamic Cresco®) on yield, chlorophyll content, level of CO2 assimilation and the effectiveness of PSII under cold stress. The values of all chlorophyll fluorescence and photosynthetic parameters significantly decreased under cold, which indicated a strong inhibition of light-phase photosynthesis in maize leaves. Predicted by the regression analysis minimum, 20 days was enough for maize plants to recover from the inhibition caused by stress damages in their photosynthetic apparatus. At the final measurement in maize growth stage BBCH 65, all the tested phytostimulators showed significant effects in increased values of effective quantum yield of photosystem II, maximum photosynthetic efficiency of PSII and electron transport rate. At this stage, Dynamic Cresco® and Nano Active® treatment significantly increased the value of maximum net photosynthetic rate (15.37% and 18.85%, respectively) and leaf chlorophyll content (7.8% and 8.7%, respectively). The application of Dynamic Cresco® significantly promoted total dry weight by 43.4% in comparison to control under stress growth conditions with cold. These phytostimulators can be used to enhance yield and physiological status of plants after abiotic stress (such as cold) to improve crop productivity, especially in organic farming.
Optimizing the Amount of Nitrogen and Seed Inoculation to Improve the Quality and Yield of Soybean Grown in the Southeastern Baltic Region
The cultivation of soybeans, especially where this species has not been grown in large areas, requires the determination of the optimal mineral nitrogen fertilization and seed inoculation with Bradyrhizobium japonicum. The purpose of the study was to determine the optimal dose of mineral N fertilization and seed inoculation treatments with B. japonicum under field conditions in the southeastern Baltic region. The objective of this study was to achieve nitrogen supply and/or inoculation with B. japonicum: check-0 kg N ha−1, 30 kg N ha−1, 60 kg N ha−1, HiStick® Soy + 0 kg N ha−1, Nitroflora + 0 kg N ha−1, HiStick® Soy + 30 kg N ha−1, HiStick® Soy + 60 kg N ha−1, Nitroflora + 30 kg N ha−1, Nitroflora + 60 kg N ha−1. Higher yields of seeds, protein and fat were found after application HiStick® Soy compared to Nitorflora. The inoculation with B. japonicum together with nitrogen fertilization improved crude protein content in seeds, biometrical features, yield components and especially the seed yield of ‘Aldana’ soybean. The highest seed yield was found after the application of HiStick® Soy and nitrogen fertilization in doses 30 kg N ha−1 or 60 kg N ha−1. Compared to the control, combined B. japonicum inoculation and nitrogen fertilization in soybean cultivation proved to be a significant factor in improving the productivity of this species in southeastern Baltic conditions.
Sustainable Methods of Soybean Cultivation in Poland
Many countries in Europe are struggling with a shortage of feed protein; moreover, efforts are being made to limit the import of post-extraction soybean meal, most often from GMO crops. To achieve the above assumptions, varietal progress is necessary and, above all, breeding work should aim at greater adaptation to regional conditions. This study was designed to evaluate the potential for growing Ukrainian soybean ‘Annushka’ in the southeastern Baltic Sea area, in accordance with the application of mineral nitrogen fertilizer and the inoculation of seeds with Bradyrhizobium japonicum. Soybean ‘Annushka’ yielded 0.98–1.68 t ha−1 in the conditions of central Poland. Our experiments have shown significant variations in seed, protein, and fat yields over the years. The maximum amounts of these characteristics were recorded in 2017. Nitrogen fertilization combined with seed inoculation with B. japonicum has proven to be an important factor in improving soybean yields; however, it slightly modified the content of organic compounds in seeds. Improvement in seed and protein yields relative to the control amounted, respectively, to Nitragina + 30 kg N ha−1 (58.8%; 72.6%), HiStick® Soy + 30 kg N ha−1 (57.6%; 68.3%), and Nitroflora + 60 kg N ha−1 (57.6%; 71.9%).
Response of New Yellow Lupin Varieties to Inoculation with Bradyrhizobium sp. Lupinus under Central European Conditions
The aim of a two-factorial field experiment was to determine how the inoculation of seeds/soil with preparations of Bradyrhizobium sp. Lupinus (Nitragina—seed inoculation, Nitroflora I—seed inoculation, Nitroflora II—soil inoculation, HiStick® Lupin—seed inoculation) affected plant development, seed chemical composition and yield of two yellow lupin varieties (Bursztyn, Puma). This experiment was carried out with four replications in 2018 and 2019 in Poland. Precipitation during both vegetation periods was similar to or lower than the long-term mean. Average seed yield of Puma was significantly greater than Bursztyn (by 0.22 t ha−1). According to the correlation coefficients, seed yield was mainly related to plant height, dry mass of nodules per plant and mass of 1000 seeds. Our results suggest that legumes, such as lupin, should always be inoculated with Bradyrhizobium, especially if they are cultivated for the first time in a field. For optimal results, the highest-quality preparations should be used. In our study, the best results were observed after HiStick® Lupin inoculation, which resulted in the highest protein content, seed yield and protein yield across all treatments.
Optimizing Soybean Productivity: A Comparative Analysis of Tillage and Sowing Methods and Their Effects on Yield and Quality
Quantitative Determination of Nitrogen Fixed by Soybean and Its Uptake by Winter Wheat as Aftercrops Within Sustainable Agricultural Systems
The future of agricultural production involves sustainable production systems with a balance between nutrients in soil–plant systems. These production systems are based on limiting the use of mineral fertilizers while introducing natural sources that increase soil fertility. The best example of such a system is plant rotation, including legumes as a forecrop for cereal plants. For this reason, the goal of the present study was to determine the possibility of obtaining nitrogen from the air using 15N isotopes and to determine the quantity of nitrogen biologically fixed and taken up by winter wheat cultivated as a succeeding plant. In field experiments, we investigated the cycle of nitrogen fixed by legume plants in rotation under sustainable conditions, as follows: soybean–winter wheat–winter wheat. After soybean seedling emergence, a mineral fertilizer (15NH4)2SO4 containing 20.1 at% 15N (a dose of 30 kg∙ha−1) was applied, with summer wheat as a reference plant. The yield of soybean reached 2.48 t∙ha−1 for seeds and 8.73 t∙ha−1 for crop residue (CR), providing a total yield of 11.21 t∙ha−1. The total biomass of soybean contained 149.1 kg∙ha−1 of total nitrogen, with 108.1 kg∙ha−1 in the seeds and 41.0 kg∙ha−1 in the residue, of which 34.0 kg∙ha−1 in the seeds and 11.4 kg∙ha−1 in the residue was biologically fixed. CR was ploughed into the soil. Plots with winter wheat cultivated after soybean (2017) were divided into two sub-plots for the application of 0 and 100 kg∙ha−1 of mineral N. The scheme was repeated in 2018. Overall, winter wheat cultivated for two subsequent years took up 8.12 kg∙ha−1 of the total nitrogen from the CR from the control sub-plot and 15.51 kg∙ha−1 from the fertilized sub-plot, of which 2.61 and 2.98 kg∙ha−1 was biologically fixed by soybean plants, respectively. The dose of fertilizer contained 5.920 kg∙ha−1 of 15N, of which 3.024 kg∙ha−1 was accumulated in soybean. In wheat cultivated as the first subsequent crop, the accumulation of 15N was as follows: 0 kg N (control)—0.088 kg∙ha−1; 100 kg N—0.158 kg∙ha−1. Meanwhile, in winter wheat cultivated as the second aftercrop, 0.052 and 0.163 kg∙ha−1 of 15N was accumulated, respectively. This study demonstrates that biological nitrogen fixation in soybeans is an underappreciated solution for enhancing crop productivity within sustainable agricultural systems. It holds significant implications for planning rational fertilizer management, reducing the application of chemical fertilizers, and improving nitrogen use efficiency within crop rotation systems.
Effects of Seed Fraction on Sowing Quality and Yield of Three-Line Hybrid Maize
Maize is one of the most productive cereal crops, and is increasingly being grown over large areas. Using the right cultivar of high-quality selected seeds for sowing can be crucial for its productivity. The aim of this study was to investigate the effect of kernel fraction on the seed quality, seed vigor, morphological traits, and seed yield of the trilinear hybrid maize cv. ‘Lokata’. The research factor was the kernel fraction, categorized based on the thousand-kernel weight (TKW) into four groups: I—small; II—medium; III–large; and IV–very large. A three-year experiment showed that increases in the TKW resulted in increases in germination and vigor up to fraction III (large seeds) in maize. Sowing maize seeds with a higher TKW resulted in plants with higher fresh and dry weights in the early stages of maize development; however, this response decreased as growth progressed. The seed yield was significantly correlated with plant height and the number of kernels per cob for all fractions sown, but the fraction did not significantly modify the seed yield of ‘Lokata’ maize.