Solanaceae plants have strong allelopathic potential, and therefore the action is confirmed through: a) bioassays with liquid or various solvent extracts and residues, b) fractionation, identification, and quantification of causative allelochemicals. Most assessments of allelopathy involve bioassays of plant or soil extracts, leachates, fractions, and residues which support seed germination and seedling growth in laboratory and greenhouse experiments. Plant growth is also stimulated below the allelopathic threshold, however severe growth reductions may be observed above the threshold concentration depending on the sensitivity of the receiving species. Generally, seedling growth is more sensitive than germination, particularly root growth. Some approaches showed that field soil collected beneath donor plants significantly reduced or somewhat promoted the growth of the recipients plants. Petri dish bioassays with aqueous extracts of different parts of donor plants showed considerable phytotoxic activities in a concentration-dependent manner with leaf aqueous extracts being most dominant. Delayed seed germination and slow root growth attributable to the extracts may be baffled with diffusion effects on the rate of imbibition, delayed initiation of germination, and particularly cell elongation; the main factor that is responsible for affecting root growth before and after the tip penetrates the testa. Light and electron microscopy extract analysis at the ultrastructural level are correctly investigated. Several Solanaceae plants have allelopathic potential, and therefore the activities, kinds and quantity of allelopathic compounds differ depending on the plant species. The incorporation of allelopathic substances into agricultural management might scale back the development of pesticides and reduce environmental deterioration.

In water systems, both biologically and chemically synthesized molecules may reduce environmental quality and influence essential ecosystems structure and function. These substances include aldehydes from various sources, also those relates to the activities of primary producers. The focus of the study was vertical distribution of several aliphatic aldehydes and phytoplankton biomass in an urban lake in Poznań (Wielkopolska Lakeland, Poland) under human pressure. Water samples were collected from surface lake to bottom, every 2 m. Plankton was analyzed under inverted and epifluorescence microscopes. The biomass was estimated from microscopic measurements and cell volume of each species. Thirteen aldehydes and acetone were analyzed using gas chromatography with an electron capture detector after derivatization and extraction processes. Aldehydes concentrations varied between 32.7 and 346.2 μg L^-1. Formaldehyde, acetaldehyde and propanal were characterized by the highest concentration both at low and high phytoplankton biomass. Phytoplankton biomass included prokaryotic and eukaryotic cells, and ranged between 0.25 and 2.94 mg L^-1. Cryptophytes and diatoms were often the most important components of phytoplankton communities, although in some cases the haptophytes and dinophytes comprised a much higher proportion. Total aldehyde concentration was significantly correlated with total phytoplankton biomass (r=0.705, p <0.05), and even higher correlation was observed between acetone and phytoplankton biomass (r=0.917). This indicates phytoplankton as an important source of carbonyl compounds in surface waters. Thus, the knowledge of different aspects of their origin and distribution in the lake is important both in ecological research and in water management.

Solanum elaeagnifolium Cav. is known to be one of the most invasive species worldwide. In this study, laboratory and greenhouse experiments were carried out to investigate the allelopathic properties of S. elaeagnifolium vegetative parts, root parts, fruit mucilage, and exudate extracts on plant communities and soil properties. In addition, the extract profiles of allelochemicals were quantified and their influence on soil properties and microorganisms was determined. Overall, the allelopathic performance of S. elaeagnifolium was established depending on the extract types, used concentrations, and target species. The doseresponse activity indicated that vegetative parts extract showed the greatest allelopathic potential followed by root parts extract. Subsequently, mucilage extract had a moderate inhibitory potential, while root exudates showed the least activity. The same trend with slight response was detected in soil properties of pH and EC properties. Polyphenols, in the range of 5.70–0.211 mg · g–1 and flavonols, in the range of 2.392–0.00 mg · g–1, were found in the analyzed samples extracted by ethyl acetate using LC-DAD-MS. The total phenol amount was 1.67 to 1.89 in the rhizosphere and 0.53 to 087 mg · g–1 in non-rhizosphere soils. Solanum elaeagnifolium exhibited a greater significant suppression of fungi count in both high and low-density areas than in rhizosphere bacteria. In conclusion, the strong and broadspectrum allelopathic potentials may enhance the ability of S. elaeagnifolium to impact seed germination and seedling growth of neighboring species. These biochemical weapons may play a critical role to facilitate their invasion and establishment in new agroecosystems.

Fall armyworm ( Spodoptera frugiperda) (FAW) is an important invasive pest of maize. The young FAW larva disrupts the photosynthetic system by feeding on the leaves. The older caterpillar interferes with pollination and fertilization processes, destroying the tassel and silks, or it bores into the maize cob, reducing harvest quality and predisposing the cob to secondary infections. The infested plant responds by channeling or converting the primary metabolites into secondary metabolites for plant defense, further reducing crop yield. The devastating feeding effect on maize becomes even more severe when maize plants are exposed to prolonged drought, during which the production of secondary metabolites is optimum. These secondary metabolites are food for herbivorous insects like the fall armyworm. Naturally, plants possess several adaptive features which enable them to cope and survive herbivorous insect attacks without compensating yield for plant defense. Such features include: thickening of the leaf cuticle of the epidermal cell walls, production of certain allelochemicals, defense proteins and the toxic chemical compound, favone glycoside (silk maysin). This review attempts to critically appraise the physiological implications of fall armyworm damage on developmental processes and maize yield. Understanding the mechanisms of various adaptive traits that confer resistance to maize against herbivorous insect damage would assist greatly in crop improvement processes.

Allelopathy refers to the beneficial and detrimental effects of one plant on another plant in both crops and weeds through the production of secondary compounds. In order to evaluate the allelopathic effects of wheat ( Triticum aestivum L.) as a crop and redroot pigweed ( Amaranthus retroflexus L.) as a common weed worldwide on each other in intercropping, these plants were cultivated under controlled conditions at Tabriz University laboratory. The ratios of wheat to redroot pigweed were, 100 : 0 and vice versa as a control, 75 : 25, 50 : 50, and 25 : 75. The results showed that at the ratio of 25 : 75 (wheat : redroot pigweed), the fresh and dry weight of roots and shoot length of wheat decreased significantly compared to the control. The fresh and dry weight of wheat shoots showed a significant decrease at different ratios compared to the control. Shoot peroxidase (POD), root superoxide dismutase (SOD), and root and shoot catalase (CAT) activities in redroot pigweed increased in all intercropping ratios compared to the control. POD activity in wheat roots was higher at all ratios than in the control. Furthermore, the ratio of 75 : 25 (wheat : redroot pigweed) led to increased activity of POD enzymes and malonedialdehyde (MDA) content in wheat shoots. Moreover, roots of redroot pigweed showed increased activity of ascorbate peroxidase (APX) and SOD enzymes and MDA content. With increased density of redroot pigweed, the soluble sugar content of wheat roots reduced significantly. However, the content of insoluble sugar and total protein increased. Root exudate compounds such as terpenoids, phenolic compounds, fatty alcohol, steroids, fatty acids, and alkanes were identified using gas chromatography/mass spectrometry (GC/MS). The findings showed that the roots were more exposed to oxidative stress due to direct contact with allelochemical compounds. Our results support the hypothesis that increasing the density can reduce the toxicity of allelochemical compounds and that increasing the activity of the antioxidant system will improve plant growth under allelochemical stress.