Anatomic characteristics of branches related to the vegetative growth of coffee tree (Coffea arabica L., Rubiaceae) under nutritional variation

Abstract

Although the anatomical tracts of the stem are used to assess the vegetative vigor of different crops, little is known about which characteristics of the vascular system contribute to the growth of coffee plants or how these characteristics are influenced by variations in macronutrients. The study objective was to understand how the growth, anatomical characteristics of the stem, and yield of coffee plants were modified by nutritional variation and which anatomical variables most contribute to growth and/or yield of the coffee plants. Growth, yield, and characteristics of the vascular system of orthotropic and plagiotropic branches of coffee plants, subjected to different percentages of NPK delivered by standard fertilization for coffee plants, had been evaluated. All the evaluated characteristics best fit the quadratic regression model. Growth, morphology, anatomy, and yield were promoted to some extent by NPK fertilization. Orthotropic branches had larger vessel diameters and ray frequencies, whereas in plagiotropic branches, vessels were more numerous. The pith area and the frequency of the rays were correlated with the height of the plant, which in turn was correlated with yield. Plant height, anatomy, and yield were modified by the fertilization. The best NPK range for plant height and yield was 100–130% of the standard. The anatomical variables most correlated with plant height were the pith area of the plagiotropic branch and the ray frequency of the orthotropic branch.