Nutrient stress has been known as the main limiting factor for maize growth and yield. Nitrapyrin, as a nitrification inhibitor—which reduces nitrogen loss—and foliar fertilizer treatments have been successfully used to enhance the efficiency of nutrient utilization, however, the impacts of these two technologies on physiological development, enzymatic responses, and productivity of maize are poorly studied. In this paper, the concentration of each stress indicator, such as contents of proline, malondialdehyde (MDA), relative chlorophyll, photosynthetic pigments, and the activity of superoxide dismutase (SOD) were measured in maize leaf tissues. In addition, biomass growth, as well as quantitative and qualitative parameters of yield production were examined. Results confirm the enhancing impact of nitrapyrin on the nitrogen use of maize. Furthermore, lower activity of proline, MDA, SOD, as well as higher photosynthetic activity were shown in maize with a more favorable nutrient supply due to nitrapyrin and foliar fertilizer treatments. The obtained findings draw attention to the future practical relevance of these technologies that can be implemented to enhance the physiological development and productivity of maize. However, this paper also highlights the importance of irrigation, as nutrient uptake from soil by the crops decreases during periods of drought.

The main goal of this research was to investigate the effects of corn smut (Ustilago maydis DC. Corda) infection on the morphological (plant height, and stem diameter), and biochemical parameters of Zea mays L. plants. The biochemical parameters included changes in the relative chlorophyll, malondialdehyde (MDA), and photosynthesis pigments’ contents, as well as the activities of antioxidant enzymes—ascorbate peroxidase (APX), guaiacol peroxidase (POD), and superoxide dismutase (SOD). The second aim of this study was to evaluate the impact of phytohormones (auxin, cytokinin, gibberellin, and ethylene) on corn smut-infected plants. The parameters were measured 7 and 11 days after corn smut infection (DACSI). Two hybrids were grown in a greenhouse, one fodder (Armagnac) and one a sweet corn (Desszert 73). The relative and the absolute amount of photosynthetic pigments were significantly lower in the infected plants in both hybrids 11 DACSI. Activities of the antioxidant enzymes and MDA content were higher in both infected hybrids. Auxin, cytokinin, and gibberellin application diminished the negative effects of the corn smut infection (CSI) in the sweet corn hybrid. Phytohormones i.e., auxin, gibberellin, and cytokinin can be a new method in protection against corn smut.

Soil conditions leading to high levels of available aluminum are detrimental to plant growth, but data are limited on genotypic differences in tolerance to aluminum stress in some crops. The aim of this study was to examine the morphological, biochemical, and physiological changes in roots and shoots of 25 common bean (Phaseolus vulgaris L.) cultivars (Pinto market class) under aluminum (Al) treatment. Additionally, this study aimed to assess the range of responses amongst the common bean cultivars relative to their Al toxicity tolerance and sensitivity. Plants were grown hydroponically using a simplified nutrient solution with or without 20 µM AlCl₃. Reactive oxygen species (ROS), activities of the antioxidant enzymes superoxide dismutase (SOD) and guaiacol peroxidase (POD), and malondialdehyde (MDA) concentration, an indicator of lipid peroxidation, were measured to establish the effects of Al treatment on the plants. In addition, growth parameters such as shoot and root dry weight, root-to-shoot ratio, root elongation, and root volume changes were also investigated. The cultivar effect was significant for all the measured parameters, except for shoot dry weight. Inhibition of the root and shoot dry weight for selected common bean cultivars shows that the response of common bean to Al stress is genotype-specific. Additionally, Al-induced root elongation inhibition and root volume changes varied among the cultivars. Most cultivars had significantly higher SOD activity (20 of 25 cultivars) and POD activity (12 cultivars) under AlCl₃ treatment compared to the controls. A positive significant correlation was observed between MDA and ROS, showing that Al stress induced the accumulation of ROS along with an increase in lipid peroxidation. According to the results of this study, Arapaho and AC Island cultivars could potentially be used in the future production of common beans under Al stress. Therefore, these two cultivars could also be included in Al tolerance breeding programs.

The benefit of applying foliar fertilizers is that crops can uptake them faster than soil fertilizers. The aim of this study was to test and valuate the effects of one zinc (Zn) and two amino acids-containing (AS) foliar fertilizers on a fodder corn hybrid’s physiological and biochemical processes. The experiment was conducted in field conditions. The following parameters of a fodder maize hybrid were measured one, two, three, four, five, and six weeks after the treatments (WAT): physiological (relative chlorophyll content and the effectiveness of PSII); biochemical (activities of superoxide dismutase (SOD); ascorbate peroxidase (APX) and guaiacol peroxidase (POD); the concentration of malondialdehyde (MDA); and proline. The yield increased by 10%, 6%, and 10% at Zn, Zn+AS1, and Zn+AS2 treatments. The yield parameters, such as grain/cob and ear weight, were also significantly higher under the applied three treatments relative to the control. The relative chlorophyll content was significantly higher one, two, and four weeks after Zn-treatment, and some changes were also observed when Zn and amino acid-containing fertilizer were applied in combination. The latter sampling did not show any notable changes. In addition, the activity of SOD increased when Zn-containing fertilizer was applied, although the effect of AS-containing fertilizer did not show. There was a correlation between the SOD activity and some of the yield parameters. The increasing SOD activity indicated a higher yield (t/ha) and a higher cob weight.

Woolly cupgrass (Eriochloa villosa (Thunb.) Kunth) is a new invasive weed in Hungary. This study was conducted to elucidate the effects of this weed on the biochemistry and growth of maize (Zea mays L. cv. Armagnac) under greenhouse conditions. Activities of the antioxidative enzymes (ascorbate peroxidase (APX), guaiacol peroxidase (POD), superoxide dismutase (SOD)), the contents of malondialdehyde (MDA), and protein were measured in the shoots and roots, whereas the content of the photosynthetic pigments was measured only in the shoots. The measured growth parameters included plant height, root length, root volume, root and shoot dry weight, and stem diameter. Results showed the allelopathic effects of woolly cupgrass on maize, with significant decreases in plant height, root length, root volume, and root dry weight. Woolly cupgrass infestation (WCI) induced significantly higher activities of APX and SOD in the shoots, whereas POD was only induced in the roots. The contents of chlorophyll-a, total chlorophyll (including relative chlorophyll), carotenoids, and root protein were substantially reduced by WCI, except for the leaf chlorophyll-b. The results suggest that high APX and SOD activities in the shoots could be involved in stabilizing the leaf chlorophyll-b, chlorophyll a/b, shoot protein, and shoot dry weight because all of these parameters were not inhibited when these two enzymes were induced. In contrast, high activity of POD in the roots is not effective in counteracting allelopathy. Therefore, it would be worthwhile to further investigate if an increase in the activities of APX and SOD in the shoots of WCI maize is responsible for stabilizing leaf chlorophyll-b, shoot protein, and shoot dry weight, which could contribute to improved maize yield under WCI.

The most important disease of European chestnut (Castanea sativa Mill.) is chestnut blight caused by the fungus Cryphonectria parasitica (Murrill) Barr which induces yield reduction in Europe and North America. This study aimed to investigate the impacts of C. parasitica infection on the physiological and biochemical characteristics of European chestnut at two different growth stages, 3 and 6 weeks after the infection. The amount of photosynthetic pigments (chlorophyll-a, chlorophyll-b, and carotenoids), the relative chlorophyll content, and the photochemical efficiency of the photosystem II (PSII) were measured in the leaves above and below the virulent and hypovirulent C. parasitica infections. The highest values were measured in the control leaves, the lowest values were in the leaves of the upper part of virulent necrosis. Antioxidant enzyme activities such as ascorbate peroxidase (APX), guaiacol peroxidase (POD), and superoxide dismutase (SOD), proline, and malondialdehyde concentrations were also investigated. In each of these measured values, the lowest level was measured in the control leaves, while the highest was in leaves infected with the virulent fungal strain. By measuring all of these stress indicator parameters the responses of chestnut to C. parasitica infection can be monitored and determined. The results of this study showed that the virulent strain caused more pronounced defense responses of chestnut’s defense system. The measured parameter above the infection was more exposed to the blight fungus disease relative to the leaves below the infection.