Aluminum tolerance measured by root growth and mucilage protection inUrochloa brizanthaandUrochloa decumbens

Abstract

Aluminum toxicity on root systems was analyzed through comparing root growth and evaluating the protective function of mucilage in Urochloa decumbens and Urochloa brizantha. Seedlings were grown in a solution with different concentrations of AlCl 3 and with mucilage removed or present. The root elongation rate, total length, number of roots and presence of aluminum at the root apex were measured. Root development was inhibited by aluminum and the elongation rate was maintained without any difference between the two species. A significant reduction in root length was found in U. brizantha. Aluminum did not influence root branching in either species and accumulated mostly in the rhizosphere of U. brizantha, where the mucilage has less of a protective function. The greatest aluminum tolerance was found in U. decumbens, observed through maintenance of total root system growth from lower to higher aluminum toxicity.

Early Seedling Growth as a Tool to Assess the Tolerance of Urochloa brizantha Cultivars to Free Aluminium

“…Similar decreases in root growth in response to aluminium were found in Jatropha curcas (Rosado et al, 2012), sorghum (Too et al, 2014), and barley (Tamas et al, 2006) in studies that used a similar methodology (e.g., measuring the root growth in seedlings in paper rolls moistened with aluminium solutions). Studies using hydroponic (Giannakoula et al, 2010;Arroyave et al, 2011Arroyave et al, , 2013Matins et al, 2011;Ramos et al, 2012;Roselló et al, 2015), semi-hydroponic (Colombo et al, 2016), and even growth in soil methods (Mutimura & Everson, 2012) have found similar results, but these methods are expensive and time consuming. Hare and Cress (1997) reported that proline accumulation occurred when wheat was exposed to water deficits, and therefore was a function of osmotic regulation and cellular protection.…”

“…According to Bitencourt et al (2011), Ramos et al (2012, and Arroyave et al (2011;2013), the Basilisk cultivar is the most resistant to poor soils and to free aluminium. Based on the dendrogram made using the phenotypic characters for both assays, it could be seen that the Basilisk cultivar was the most distant cultivar in both dendrograms (Figure 7).…”

Tolerância diferencial ao alumínio em plantas do gênero Brachiaria: morfologia de raízes, sistema antioxidativo e alumínio trocável no apoplasto radicular

“…Os rebanhos bovinos, muitas vezes estão localizados em áreas com solos de baixa fertilidade, ácidos e com altos teores de alumínio trocável (Al 3+ ), limitando o potencial produtivo das plantas e, consequentemente, comprometendo os índices zootécnicos. Na região de Cerrado, principalmente, atribui-se a redução do crescimento das plantas à acidez do solo, ao excesso de Al e baixos teores de fósforo (RAMOS et al, 2012 (EMBRAPA, 2006). Considerada espécie perene, os rizomas apresentam-se em forma de nódulos pequenos.…”

“…O ápice radicular, e particularmente a parte distal da zona de transição, é a região mais sensível ao estresse induzido pelo Al (SIVAGURU;HORST, 1998;KOLLMEIER;FELLE;HORST, 2000;HUANG et al, 2009). O sintoma de toxidez causada por Al é facilmente observado pela inibição do crescimento radicular, encurtamento e o espessamento das pontas radiculares, prejudicando a formação de raízes finas, o que consequentemente reduz a absorção de água e nutrientes pelas plantas (KERRIDGE;DAWSON;MOORE, 1971;FOY, 1976;KOCHIAN, 1995 (BITENCOURT et al, 2011;RAMOS et al, 2012).…”

“…Acúmulo de alumínio nas folhas (mg/vaso) Basilisk e B. brizantha cv. Marandu são genótipos considerados tolerantes ao Al RAMOS et al, 2012;. Contudo vale ressaltar, que no presente estudo a B. brizantha cv.…”