Crescimento inicial e eficiência fotoquímica de mangueiras cultivadas em solo contendo lama do Rio Doce

Abstract

This work evaluated the effects of different concentrations of mud from the Doce River containing mining residues resulting from the breakage of the Mariana dam occurred in the year 2015 on the growth and photosynthetic activity of Mangifera indica L. Ramos seedlings of the cultivars Rosa, Tommy Atkins and Palmer, grafted by grafting on the cv. Óleo were submitted to three different concentrations of mud (0%, 20% and 50) containing Doce River mining residues. The physical and chemical properties of the substrates were analyzed and, simultaneously, the macro and micronutrient contents of the leaves of the cultivars were evaluated. Growth measures and photosynthetic analyzes were performed monthly between October 2016 and October 2017. In the last month, the amount of fruit was measures. The photochemical parameters that best represented the effects of the mining residues contained in the mud of the Doce River during the development of the seedlings were the Total Performance Index of the photosynthesis photochemical stage (PITOTAL), the Performance Index of Photosystem II (PIABS) and the Energy Flow Dissipated by Active Reaction Center at time zero (DI0 / RC). The damages caused were evident in cv.Rosa verified by growth analyzes, chlorophyll indices, Chlorophyll a fluorescence induction curves (OJIP curves) and JIP test parameters. The results of the macro and micronutrients foliar revealed that cv.Rosa (Treatment 50%) showed toxic levels of Manganese, and may have contributed to the observed stress. The results indicated that cv.Rosa presented symptomatic severity, resulting in less developed seedlings, while the cultivars Tommy Atkins and Palmer demonstrated to have mechanisms of tolerance to the stresses caused by the mining residues contained in the mud of the Doce River.