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The increase in zinc (Zn) content in orchard soils caused by successive applications of fertilizers and fungicides to control foliar diseases can modify the structure of the roots of young peach trees. The study aimed to evaluate the effect of the application of Zn doses in soil on the morphological and anatomical structure of the roots and on the growth of young peach plants grafted on three clonal rootstock cultivars. Samples of a Typic Hapludalf were collected, air dried, sieved and subjected to the application of 0, 60 and 120 mg Zn kg−1. After the incubation period, one plant of each rootstock cultivar (Flordaguard, Rigitano and Tsukuba-1) was transplanted into rhizoboxes and grown for 65 days. In the shoots, we determined dry matter production and Zn concentration in tissue. In the roots, we analyzed root morphology using light microscopy. The increase in the availability of Zn in the soil stimulated the production and accumulation of phenolic compounds in the cortex and vascular cylinder of the roots, in addition to increasing the concentration of Zn in plant tissue to values ​​above those considered normal. Rigitano and Tsukuba-1 rootstock cultivars exhibited cell rupture in the cortex, resulting in the formation of intercellular spaces. Flordaguard rootstock cultivar was the least sensitive to morphological and anatomical changes in the root apex and, therefore, may be the most recommended for cultivation in soils with high Zn contents.

Hesperozygis ringens (Benth.) Epling is an endangered Lamiaceae woody herb characterized by the abundance of essential oil (EO) in its leaves. However, no information has been found in literature about the plant tissues where this extractive is biosynthesized, and what other constituents are produced by the organ. In addition, the classes of compounds biosynthesized by its petals and the composition of EO produced by the inflorescences have not been reported either. Because this information may help the H. ringens identification, the aim of this study was to characterize the compound classes in the plant leaf and petal by histochemical tests. The leaves and flowers of this species were collected from a population in Santo Antao, municipality of Santa Maria, Rio Grande do Sul, Brazil. Fresh plant material was analyzed to detect total lipids; acid and neutral lipids; essential oils (EOs), resins and oil-resins; proteins; starch; phenolic compounds; tannins; flavonoids; and alkaloids. The EOs of leaves and inflorescences were extracted by hydrodistillation and their chemical compositions were analyzed by gas chromatography coupled to mass spectrometry (GC–MS) and GC with flame ionization detector. Results obtained in histochemical tests detected total, neutral and acid lipids, EOs, oil-resins, protein, phenolic compounds, flavonoids and alkaloids in the leaves and petals of H. ringens. Total lipids were found mainly in leaf mesophyll and glandular trichomes of both plant organs. Essential oils were marked in leaf vascular bundle, petal surface and glandular trichomes of both fresh organs. Oil-resins were detected mainly in leaf mesophylls and petal glandular trichomes. The chemical characterization of the EOs produced by leaves and inflorescences detected the oxygenated monoterpenoid pulegone as their major compound. The species presented histochemical characteristics which have not been found for other Lamiaceae representatives yet, and may serve to identify H. ringens.