Drought is considered the main abiotic stress because it influences the distribution of plant species and limits the productivity of ecosystems. The aim of this study was to evaluate the effects of drought on physiological and biochemical parameters during the initial development of Vatairea macrocarpa, a native cerrado species. Plants were subjected to daily watering (control); suppression of watering during 90 days with field capacity (fc) 50% and 25% and then followed by rewatering. Relative leaf water content (RWC), gas exchange, photosynthetic pigments content, carbohydrate and amino acids content, antioxidant activities and growth were recorded. The RWC decreased according to the soil water restriction, causing reduction in stomatal conductance and decrease of 76.4% in net photosynthesis in plants submitted to 25% fc. Water restriction decreased the chlorophyll content, however increased carotenoid content and also improved the antioxidant activities of superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT). In addition, high levels of sugars (sucrose, raffinose) and amino acids (proline, tryptophan, valine, glutamine and GABA) were detected in drought stressed plants, contributing to osmoregulation and as sources of carbon and nitrogen after rehydration. Decreases in carbon assimilation promoted a reduction of the leaf area, however an increase in the root surface area was observed. After rewatering, the analized parameters became similar to the control plants indicating that the severe water stress did not impair the survival of young plants. Instead, adjustments were made to protect them against drought such as the maintenance of the assimilatory metabolism at minimal levels.

The mulberry tree (Morus alba) is a perennial and fast-growing tree distributed worldwide under different climatic conditions. Most of the world’s silk production (>90%) is facilitated by the feeding of silkworm larvae on the leaves of mulberry (Morus alba L.) varieties. Therefore, exploration of the protocol for improving the propagation efficiency and increasing the reproductive capacity of M. alba varieties could be of great significance. This study aimed to determine the effect of four concentrations (0, 100, 200 and 400 mg L⁻¹) each of naphthaleneacetic acid (NAA), indole-3-butyric acid (IBA), and zinc sulfate (0, 100 and 200 mg L⁻¹), supplied separately or combined, on the rooting and growth of mulberry cuttings. M. alba cuttings were immersed for 5 s in each solution using the quick-dip method and subsequently, the cuttings were dried and planted in plastic pots and maintained in a greenhouse for 60 days. The number of leaves (NL), longest root size (LRS), longest stem size (LSS), number of rooted cuttings (NRC), number of stems per tree (NSP), rooting percentage (RP), wet root weight (WRW), dry root weight (DRW), wet stem weight (WSW), dry stem weight (DSW), wet leaf weight (WLW) and dry leaf weight (DLW) were evaluated. The results obtained showed an increase in all growth parameters of the mulberry cuttings. Treatments of hormones (IBA and NAA) and Zn sulfate were effective on LSS, LRS and WSW. The highest values of LSS were obtained for the treatments T5, T6, T14, T15, T16 and T18. Moreover, T5, T12 and T10 showed the highest values of LRS. The highest value of WSW was observed for T18, T5, T14, T15 and T16. The highest values of WLW and DLW were observed in T20 and T14. Dry stem weight (DSW) was high in T18 and T14. The application of NAA (at 200 mg L⁻¹), IBA (200 and 400 mg L⁻¹) and Zn sulfate (200 and 400 mg L⁻¹), either alone or in double combination, can be a suitable and reliable method for mulberry propagation.