Abstract
The beneficial effects of silicon (Si) fertilization have been observed for several plant species, especially when submitted to stress, either biotic or abiotic. Among the possible reasons for the greater adaptability and resistance of brachiaria grass in areas of low fertility soils in Brazilian savanna, stands its capacity of absorbing and accumulating Si in aerial parts. To evaluate the effect of Si on dry matter yield of Brachiaria decumbens Stapf and Brachiaria brizantha Hochst, grown under two soil moisture regimes, a trial was set up in a completely randomized design factorial scheme (5 × 2 × 2), with five Si rates: (0; 242; 484; 968 and 1,452 kg ha-1), two soil water tensions (60% and 80% of field capacity) and the two brachiaria species. The experiment was installed in a greenhouse, using one of the most representative soils in the region under cerrado, Typic Haplustox. Both brachiaria species can be considered Si-accumulating plants, since they present high Si contents in their aerial parts. Application of Si to the soil increased the contents of this element in both grass species but did not change their tolerance to water deficit, and did not affect dry matter yield.
Highlights
Silicon (Si) has received little attention from plant nutrition scientists, most likely because it is not included in the group of elements considered as essential to plants
Notwithstanding, beneficial effects of Si have been demonstrated for many plant species, especially when these plants are submitted to some type of stress, whether biotic or abiotic (Takahashi, 1995; Korndörfer et al, 1999; Faria, 2000; Datnoff et al, 2001)
The role played by Si in these plants can be linked to a reduction in the toxic effects of aluminum, manganese and iron, as previously observed for other grasses, and because it is responsible for regulating transpiration, which is the likely reason for the resistance shown by this grass to water deficits which occur in the savanna, in addition to protecting the leaves against pest and disease attacks (Cocker et al, 1998; Ma et al, 1997; Datnoff et al, 2001)
Summary
Silicon (Si) has received little attention from plant nutrition scientists, most likely because it is not included in the group of elements considered as essential to plants. Silicon absorbed by the roots in the form of monosilicic acid (H SiO ) is carried through the plant and deposited in the leaves. Still little discussed, for the ruggedness shown by brachiaria grasses when developing under savanna soils, could be its greater capacity in absorbing and accumulating Si. The role played by Si in these plants can be linked to a reduction in the toxic effects of aluminum, manganese and iron, as previously observed for other grasses, and because it is responsible for regulating transpiration, which is the likely reason for the resistance shown by this grass to water deficits which occur in the savanna, in addition to protecting the leaves against pest and disease attacks (Cocker et al, 1998; Ma et al, 1997; Datnoff et al, 2001)
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