Influência do Si em plantas de braquiária sob estresse salino

The present work had the objective of evaluating the effects of different concentrations of Siin the nutrient solution without and with saline stress on the growth and production of B. brizanthacv. MG-05 in different vegetative stages. The application of Si has provided increasedresistance of plants to conditions of biotic (attack of phytopathogens) and abiotic stresses (water stress, osmotic, saline, heavy metals, acid rain, excess light and ultraviolet radiation).The mechanisms by which Si induces increased plant resistance to biotic and abiotic stressconditions are similar. With the induction of resistance in plants there is a series of reactionswith the “new” biosynthesis of proteins and enzymes and increased photosynthetic activity ofthe plants, causing a drain of metabolites and N in plants. Brachiaria (Brachiaria brizantha)was chosen because it is a Si accumulator and also because it is used in most pastures of thesouthern Agreste Pernambuco dairy basin. The experiment was carried out in a greenhouse atthe Garanhuns Academic Unit of the Federal Rural University of Pernambuco (UAG / UFRPE).The plants were grown in six-liter pots containing Hoagland nutrient solution and treatmentsand received constant aeration via the compressor. The experimental design was a completelyrandomized 5 x 2 factorial design, with five concentrations of Si in the nutrient solution (0, 1,2, 3 and 4 mmol L -1 of Si) and two concentrations of NaCl (0 and 40 mmol L -1 of NaCl) with4 replicates, totalizing 40 vessels. During the development cycle of the plants, four collectionswere carried out, with each plant being harvested one plant per pot, totaling four plants pertreatment. The collections started at 20 days after sowing (DAS) and followed at 27, 42 and57 DAS. On the day of collection the first fully expanded leaf of the most developed tiller wasselected, where a segment of 169.72 mm2 was weighed and weighed to determine the specificleaf area (AFS). Subsequently, the samples were weighed and dry mass of shoot (MSPA), root(MSR) and total (MST) was determined. Up to 42 days after sowing (DAS) the Si increased thedry mass production of plants cultivated without NaCl in the medium and reduced the deleteriouseffects of the salinity with the concentrations between 2.5 and 2.7 mol L-1 of Si.