Mineral Composition of Macronutrients in Shoots of Blackberry Plants Under Nutritional Deficiencies

This study investigated the mineral nutrition of the blackberry plants under Brazil environmental conditions. The goal was to evaluate the effect of single macronutrient omissions in the nutritional status of blackberry (Rubus ssp.). Blackberry plants (‘Brazos’ cultivar) were propagated by cuttings. After 3 months, the cuttings were transferred to a Hoagland and Arnon solution culture, which was initiated with 10% of ionic force (i.e., adaptation period), with constant aeration. The experiment was conducted in a controlled environment (glasshouse) in a completely randomized design with nine treatments corresponding to a complete Hoagland and Arnon solution (i.e., control) and individual omission (i.e., minus) of either N, P, K, Ca, Mg, S, B or Fe with three replicates. The plants were harvested and the plant height and stem diameter at the base were recorded. After harvest the plants were separated into shoots and roots. The plants tissues were dried at 70º C and then they were weighed and ground, and then the dried plant samples were analyzed. The blackberry plants with the lowest nitrogen concentrations were the treatments -N, -P and -S.  For phosphorus concentration, the smallest values were in the plants with the nitrogen omission. The highest potassium concentrations were observed in the treatments -Ca and -Mg while the highest calcium concentration was in the treatment -N. For magnesium concentration, the highest values were found in plants with omissions of N and K. The highest values of sulfur concentrations were observed in plants grown with no K, Ca, B or Fe. The omission of nutrients caused changes in the nutritional status of blackberry. The concentrations of macronutrients found in the control treatment were (g.kg^-1): N 11.40, P 1.38, K 9.38, Ca 5.70, Mg 2.30 and S 1.46. The decreasing order of nutrient content in the shoots was N> K> Ca> Mg> S> P.