Greater contribution of low-nutrient tolerance to sorghum and maize growth under combined stress conditions with high aluminum and low nutrients in solution culture simulating the nutrient status of tropical acid soils

Abstract

Aluminum is usually regarded as the determining factor for plant growth in acid soils and nutrient deficiencies are often additional growth‐limiting factors in tropical acid soils. Taking into account the potential interactions between Al toxicity and nutrient deficiencies, the present study investigated sorghum (Sorghum bicolor Moench [L.]) and maize (Zea mays L.) cultivar differences for: (1) Al tolerance (relative growth in a one‐fifth strength nutrient solution [low‐nutrient medium, ionic strength: 4.5 mmol L−1] with Al and without Al), (2) low‐nutrient tolerance (relative growth in a low‐nutrient medium compared with growth in a full‐strength nutrient solution), (3) combined tolerance (relative growth in a low‐nutrient medium containing Al compared with a full‐strength medium lacking Al). The goal of the present study was to identify the predominant growth‐limiting factor using a solution culture medium that simulates the nutrient status of tropical acid soils. Differential Al tolerance among 15 cultivars of sorghum and 10 cultivars of maize in short‐term assays (2.5 or 20 µmol L−1 AlCl3 in 0.2 mmol L−1 CaCl2 at pH 5.0 or 4.9, respectively, for 24 h) was positively correlated with Al tolerance in long‐term cultures (11.1 or 42.6 µmol L−1 soluble Al in the low‐nutrient medium at pH 4.5 or 4.3, respectively, for 29 days). However, the level of Al tolerance in the short‐term assays was not correlated with the combined tolerance, suggesting that a short‐term screening technique may not be practically useful for estimating cultivar adaptation to a combination of stress factors in tropical acid soils. In sorghum, a less Al‐tolerant plant species, higher Al tolerance was associated with less Al absorption by the roots and greater K translocation into the shoots. In maize, a more Al‐tolerant plant species, there was no correlation between the accumulation or transport of elements and Al tolerance. Standardized partial regression coefficients suggested that low‐nutrient tolerance contributed more to combined tolerance than Al tolerance under most conditions (except for Al‐sensitive sorghum at 42.6 µmol L−1 AlCl3). A greater combined tolerance was associated with a higher K shoot concentration in sorghum and a higher Ca shoot level in maize. Plant nutritional characteristics linked to low‐nutrient tolerance should be evaluated as an important strategy for plant production in tropical acid soils, both for Al‐tolerant plant species and for Al‐sensitive plant species under low‐Al conditions.

Higher sterol content regulated by CYP51 with concomitant lower phospholipid content in membranes is a common strategy for aluminium tolerance in several plant species

“… Khan et al (2009) reported that Al tolerance was positively correlated with the ratio of sterols to phospholipids in root-tip cells of various rice cultivars. Application of uniconazole-P, an inhibitor of obtusifoliol-14α-demethylase (OBT 14DM), decreased the sterol content in root-tip cells of rice.…”

Wheat genotypes differing in aluminum tolerance differ in their growth response to CO2 enrichment in acid soils

“…It has been suggested that mineral stress resulting from either deficiencies in mineral nutrients and/or toxicity of excessive minerals may play an important role in our understanding how global climate change will affect plants in real world soils (Lynch and St.Clair ; Akhter et al. ). However, the majority of research on the effect of elevated [CO 2 ] on plant growth has mainly focused on the interaction between elevated [CO 2 ] and the mineral nutrients essential for plant growth and development so far, whereas a few studies have examined the responsiveness of plant growth to [CO 2 ] enrichment in the presence of toxic metals in soils.…”

Variación de la fitotoxicidad al aluminio en solución de ecotipos de bromo (Bromus valdivianus Phil.)

“…Similares resultados encontraron Rengel y Robinson (1989). Por otro lado, Akhter et al (2009) señalan que en un experimento con sorgo en solución nutritiva, los resultados indicaron que entre las menos tolerantes al Al, la mayor tolerancia estaba dada por una menor absorción de Al en las raíces. Marín-Garza et al (2010), señalan que en un experimento con arroz en solución nutritiva, las concentraciones de Al en la parte aérea aumentaron en relación al aumento de la concentración de Al en solución.…”