Zn application does not alleviate plant stress Cr in wild passion fruit seedlings

Aplicação de Zn não alivia o estresse de Cr em mudas de maracujá silvestre

Abstract

Heavy metals (HMs) can be classified as essential (e.g., zinc, Zn) or non-essential mineral elements (e.g., chromium, Cr) for plant development. Several wild species show environmental survival potential in soil contaminated with HMs, but the initial plant growth (seedling) stage has not been elucidated. The hypothesis tested whether Zn supply alleviates Cr stress during seedling growth and initial establishment of Passiflora cincinnata Mast. cv. ‘BRS Sertão Forte’ (wild passion fruit). The factorial experiment 2x2 considering Zn and Cr dosages was carried out in a nursery production system with a nutrient solution of Hoagland and Arnon (1950) nº2 (50% of ionic strength), applied via roots to supply 10 plant replicates completely randomly distributed. We quantified plant height (cm), leaf area (dm 2 ), plant length (cm), total number of leaves (units), and photosynthetic pigments, such as chlorophyll a (µmol.L -1 ), chlorophyll b (µmol.L -1 ), and carotenoids (µmol.L -1 ). The data were analyzed using Mixed Analysis of Variance (MIXED ANOVA) and the differences between means were tested using Student’s test with a significance level of 5%. Our results showed that Cr has a harmful effect on plant growth parameters, but it also led to an increase in the expression of plant physiology parameters. However, Zn had no significant effects, except for the leaf area, or interactions with Cr. Therefore, in conclusion, we reject the hypothesis that Zn supply alleviates Cr stress during the initial establishment of P. cincinnata seedlings.