Effects of thermotherapy and meristem culture techniques on macro and micronutrients content in elephant grass cultivars

Elephant grass is a tropical forage crop highly used in dairy cattle production, in Brazil. It has been getting special attention, because of its bioenergy potential, medicinal properties, and bioremediation profile. The aim of the present study is to investigate the effects of thermotherapy based on clonal cleaning methods and meristem culture on the mineral content of elephant grass (Cenchrus purpureus (Schumach.) Morrone). Cultivars “Mineiro”, “Taiwan A-147” and “Pioneiro” were subjected to the following methods: thermotherapy (T) combined to meristem culture (MC), meristem culture and mature stems (control). The experiment assessed the mineral contents of phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and sulfur (S) at three cuttings, which were performed every 60 days, for 180 days. There was lack of effects from these methods on the mineral content of approximately 66% of the carried out assessments, standing out unanimity for all cultivars, methods, and most of the cuts. T+MC was the only method showing positive effect on P and Ca content, in all cuts, in the cultivars Taiwan A-147 and Pioneiro, respectively. There was clear negative effect of cleaning methods on P and Ca content, in all cuts, for cultivar Mineiro, and on Mg, for cultivar Taiwan A-147. These results, along with the positive effects observed in vegetative and nutritional parameters shown in other articles published in this Journal, show that the clonal cleaning methods are strongly recommended for cultivars with more than 15 years of ripe stem propagation.