Photosynthetic and growth parameters of Pfaffia glomerata in zinc dose cultivation

Resumo

The objective of the present work was to analyze the influence of zinc doses on biomass production, root biometry and photosynthesis in Pfaffia glomerata plants. A genotype of the species was used to obtain the seedlings through in vitro propagation. In a greenhouse, the plants were cultivated, using four doses of Zn as treatment: 0.5; 50 75 and 100 µM. The nutrient solutions were applied for 84 days, at the end of which photosynthetic parameters and biomass production were analyzed. From the root system, 25% were frozen for further analysis of root biometry. Data were subjected to statistical analysis using the Scott-Knott test with a 5% significance level. It was observed that the production of fresh biomass was reduced mainly in the aerial part for the treatments of 75 and 100 µM. Root length, surface area and volume were reduced in the 50 and 75 µM treatments. The transpiration and assimilation rate, stomatal conductance, water use efficiency, carboxylation efficiency, were the affected photosynthetic parameters. Visibly, the plants showed variation in leaf color. It is concluded that P. glomerata tolerates small excesses of Zn, managing to survive under these conditions, despite showing small changes in its growth and development.