Tolerance of <i>Urochloa brizantha</i> cv. MG5 to Mn Toxicity

Abstract

Available information of the effects of manganese nutrition on the forage genus Urochloa is scarce. In the context, this study aims to evaluate the tolerance of Urochloa brizantha cv. MG5 to Mn toxicity. The experiment was conducted in a greenhouse at the University of the State of Sao Paulo (UNESP) in the city of Jaboticabal, SP. Plants were cultivated in vases (3.5 L) filled with soil according to a completely randomized experimental design comprising of five levels of Mn (0, 15, 30, 60 and 120 mg·dm ) and four replications and cut in two periods: one is 42 days after sowing and the other is 30 days after the first one. Samples from both cuts were evaluated as to plant height, number of leaves and tillers, dry weight, Mn content and accumulation, and the green index was determined in the last cut. Manganese addition to soil caused an increase in chlorophyll content at the dosage of 68 mg·dm −3 observed in the second plant cut. Dosages of Mn above 15 mg·dm −3 did not induce increases in nutrient accumulation and in the number of leaves in the first and second cuts of the grass, and tillers in the first cut. The highest concentrations of manganese in the shoots did not produce visual symptoms of damage or a decrease in forage productivity demonstrating that Urochloa brizantha cv. MG5 has high tolerance to manganese toxicity.

Tolerance of Marandu Grass to Excess Iron and Manganese

“…Also in rice cultivars, Fageria et al (2008) found a reduction in the leaves and roots dry mass as the concentration of Fe increased. Treatments SDM RDM TDM ----------------------g plant -1 --------------------Adequate Fe and Mn 9.12 a 2.17 Cavalcante et al (2013), evaluating the tolerance of cv. MG5 to the toxicity of manganese (0, 15, 30, 60 and 120 mg dm -3 ) observed that the shoot dry matter of the grass showed reduction in the second cut of the grass; however, for root dry matter there were no symptoms of reduction; nonetheless, the plants showed reductions in all variables evaluated.…”

Manganese accumulation and dry matter production of Guinea Grass (Panicum maximum) after application of increasing doses of Mn fertilizer

“…The Mn 2+ content in the shoot at the second cut showed quadratic adjustment due to the application of Mn 2+ increasing rates, with the maximum content of 568.74 mg kg -1 obtained with 81.64 mg dm -3 (Fig 2). Cavalcante et al (2013) found plants of Urochloa brizantha cv. MG5 not showing significant effects at the second cut, when subjected to Mn similar rates used in this study.…”