Resposta do trigo ( Triticum aestivum L.) ao boro em condições contrastrantes de acidez do solo - DOI:10.5039/agraria.v12i2a5432

Wheat cultivation in acid soils may be simultaneously limited by metal toxicity, deficiency or Ca and Mg imbalance, and B deficiency. The aim of the present study is to assess whether the wheat response to B increases, as the crop condition in the acid soil becomes more stressful. The study was conducted in a greenhouse, and an Oxisol sample was used as the substrate. It assessed the interaction between three soil acidity treatments (low [pH-CaCl2 5.6], very high [pH-CaCl2 4.2] and very high acidity with gypsum [pH-CaCl2 4.3]) and five B treatments (0, 0.15, 0.40; 1.25 and 3.50 mg dm-3). The very high addition of gypsum into a very acid soil caused a nutritional imbalance in wheat (mainly to Mg) and led to lower dry matter accumulation values, a condition in which B presented stress alleviation. Such condition resulted in significant changes in root growth, transpiration and the availability of Mg and Ca/Mg ratio in the rhizosphere soil. The concentration of K, Ca, Mg, P, Fe, Mn, Zn, Cu and Al was little affected by B, since the K:Mg ratio was more important. The treatment with very high acidity, with gypsum, also showed higher B toxicity. Thus, wheat has shown higher B response in acid soil under the most stressful condition.