Temperature strongly influences the growth of maize, particularly in the early growth stages. The exogenous application of some amino acids has been proven to have a positive effect on plant growth and development under stressful conditions. The objective of the study was to evaluate the response of maize that was grown under an optimal and stress (fluctuating) temperature to L-Arginine (L-Arg) and Glycine (Gly) application. In the study, it was assumed that the exogenously applied amino acids would alleviate the adverse effects of temperature stress on the maize height, as well as on the biomass of shoots and roots. Ten concentrations of each amino acid from 0.006 mM to 9.0 mM were tested under constant temperature conditions 20–22 °C/23–25 °C (night/day) an fluctuating stress of rising and dropping temperatures between 12–15 °C (night) and 30–38 °C (day). The amino acids were applied to the crop at growth stages V3–V4. In plants that were obtained from seeds pre-treated with L-Arg and Gly, the amino acids increased both the length of radicles and the number of lateral roots. A large discrepancy between the effects of the two amino acids was observed after foliar application. Under optimal thermal conditions, L-Arg increased the mass of shoots and roots by 55–59%. Under stress conditions, root mass was increased even by 100% when compared to the control plants. The best results were recorded at concentrations of 6 mM and 3 mM. Plants that were treated with Gly concentrations generally reached the height of untreated plants or less. It was shown that Gly applied at concentrations of 0.2 mM to 3 mM has a negative effect on the fresh mass of the crop.

The exogenous application of salicylic acid prevents plant damage caused by various abiotic stresses (drought, high and low temperatures, salinity) and helps plants to build resistance to biotic stresses (pathogens). Acetylsalicylic acid, which is a synthetic salicylic acid derivative, has the same properties. In the face of climate change and a greater likelihood of extreme weather events, the use of these acids can significantly help to ensure proper growth and development of plants, especially sensitive species, even under stress conditions. The problem, however, is choosing the right dose (concentration) and time of application, and individual species sensitivity. The aim of the study was to assess the effect of acetylsalicylic acid on the growth and yield parameters of spring wheat. A field trial was carried out in 2013 and 2014 at the Institute of Plant Protection—National Research Institute in Poznan (Poland). The experiment was established on spring wheat cv. ‘Tybalt’, in four replications. Acetylsalicylic acid was tested in two concentrations: 0.3 and 0.5 mM. Each concentration was applied to the crop twice at growth stage BBCH 29 (end of tillering) and 7 days afterwards, and at growth stage BBCH 37 (flag leaf just visible) and 7 days afterwards. The study evaluated 12 traits of the crop, including plant height, chlorophyll content in the flag leaf, length of the ear, and quality and quantity parameters of the yield. The study showed that both the selection of the appropriate concentration and the time of acetylsalicylic acid application have a significant impact on the growth and development of the wheat. The acetylsalicylic acid increased the amount of chlorophyll in the leaves, the number of grains in the ear, the mass of a thousand grains, and grain yield. The present study did not confirm significant differences between the acetylsalicylic acid concentrations. The concentration of 0.5 mM proved more effective only for such traits as plant height and protein content in the grain. The study showed that it is not the concentration but the time of acetylsalicylic acid application that is more important for the growth of the wheat. Although there were no significant differences between the effects of earlier and later application time on plant height or chlorophyll content, most of the structural and qualitative parameters of the yield (number of grains in the ear, grain density, grain hardness, protein, gluten and starch content) were better after later application of acetylsalicylic acid (GS BBCH 37).

The northern root-knot nematode, Meloidogyne hapla, is a major pest of many crop species. The objective of the study was to determine how M. hapla population dynamics is affected by two precrops, i.e., Trifolium pratense and Medicago sativa, in three crop durations: one, two and three years of continuous cultivation. Moreover, we set ourselves the task of evaluating the effect of the legume precrop soil on the growth of the succeeding tomato plant (Solanum lycopersicum) and on the nematode population. The experiment was performed outdoors in pots with naturally infected soil. Both precrop species investigated were found to modify the J2 nematode population density in the soil. The galls and nematode females with egg masses were observed on the roots of both studied plant species at the end of each growing season. They appeared to be more abundant on the red clover roots than on those of the alfalfa. The obtained data indicate that the spring soil sampling is more appropriate for the estimation of the M. hapla population density in the red clover precrop soil. The legume precrop soil had a limiting effect on tomato growth and fruit yield. The nematode population negatively influenced tomato growth. The experiment revealed that tomato plants could be planted in alfalfa precrop soil following at least three years of continuous alfalfa cultivation. The same cannot be said of the cultivation of red clover as a precrop for tomatoes.

Meloidogyne hapla is a serious pest of many cultivated plants. In response to the economic significance of the species, efforts are being made to develop a new method to reduce its harmful effects on crops. The aim of the study was to determin...