Foliar sampling time and critical level diagnosis of nutrients for blackberry

Abstract

Foliar analysis makes it possible to accurately diagnose nutritional deficiencies, which are difficult to be identified by soil analysis or visual diagnosis. The moment to carry out the foliar analysis is essential so that the results can be used for fertilizing, with the results from the soil analysis, to ensure the growth of the plant. Thus, this study aims to assess the best foliar sampling time and to propose the critical levels of nutrients for the nutritional diagnosis of the blackberry. The soil in the experimental area is Typic Quartzipsamment, which has 83% sand, 10% clay and 7% silt. The experiment was done in an orchard with six and seven years old blackberries (Rubus spp.), ‘Brazos’, ‘Guarani’, ‘Tupy’ and ‘BRS Xavante’. Foliar sampling was done during vegetative growth, beginning of flowering and fruiting of plants. The determination of the best sampling time has been evaluated from the foliar nutrient content and the productivity. Critical nutrient levels were proposed with the methodology of reduced normal distribution. The best moment for foliar sampling of blackberry to evaluate nutritional status is at the beginning of flowering. The critical levels proposed for macronutrients (g.kg⁻¹) are 25.5 for N; 2.0 for P; 11.2 for K; 2.9 for Ca; 0.3 for Mg and 2.1 for S, and for micronutrients (mg.kg⁻¹), 15.5 for B; 9.7 for Cu; 79.6 for Fe; 116.4 for Mn and 22.9 for Zn. These levels for P, K, Ca, Mg, S and B are below the ranges considered suitable for blackberry.

Keywords:

• Rubus
• mineral nutrition
• foliar analysis
• management

Disclosure statement

No potential conflict of interest was reported by the author(s).