Influence of Si on Brachiaria plants under salt stress
Keywords:
Forage, Mineral nutrition of plants, ResistanceAbstract
The present work had the objective of evaluating the effects of different concentrations of Si
in the nutrient solution without and with saline stress on the growth and production of B. brizantha
cv. MG-05 in different vegetative stages. The application of Si has provided increased
resistance 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 stress
conditions are similar. With the induction of resistance in plants there is a series of reactions
with the “new” biosynthesis of proteins and enzymes and increased photosynthetic activity of
the 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 the
southern Agreste Pernambuco dairy basin. The experiment was carried out in a greenhouse at
the 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 treatments
and received constant aeration via the compressor. The experimental design was a completely
randomized 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) with
4 replicates, totalizing 40 vessels. During the development cycle of the plants, four collections
were carried out, with each plant being harvested one plant per pot, totaling four plants per
treatment. The collections started at 20 days after sowing (DAS) and followed at 27, 42 and
57 DAS. On the day of collection the first fully expanded leaf of the most developed tiller was
selected, where a segment of 169.72 mm2 was weighed and weighed to determine the specific
leaf 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 the
dry mass production of plants cultivated without NaCl in the medium and reduced the deleterious
effects of the salinity with the concentrations between 2.5 and 2.7 mol L-1 of Si.