Growth and nutrient uptake patterns in plants of Duboisia sp

Abstract

Characterizing growth and nutrient uptake is important for the establishment of plant cultivation techniques that aim at high levels of production. The culturing of Duboisia sp., although very important for world medicine, has been poorly studied in the field, since the cultivation of this plant is restricted to a few regions. The objective of this paper is to characterize growth and nutrient absorption during development in Duboisia sp. under a commercial cultivation system, and in particular to assess the distribution of dry matter and nutrients in the leaves and branches. Our work was performed on a commercial production farm located in Arapongas, Paraná, Brazil, from March 2009 to February 2010. A total of 10 evaluations took place at approximately 10-day intervals, starting 48 days after planting and ending at harvesting, 324 days after planting. The growth parameters analyzed were the height of the plants and the dry matter of the leaves and of branches, while the chemical composition of the leaves and branches was used to study nutrient absorption. Data were submitted to regression analysis. Growth in height followed Richards’ model, mirroring the rise in air temperature and water availability. Phytomass accumulation in the aerial parts of the plants was slow during the first 150 days, but grew 25 times from that point to harvesting. Starting from 260 days, phytomass accumulation in the leaves began to be notable, while in the branches, a growth of 169% occurred, a pattern of biomass partitioning that is unfavorable for the producer. Accumulation of nutrients mirrored the accumulation of phytomass, showing the same unfavorable partition. The nutritional demand for macronutrients and micronutrients was, respectively, N < K < Ca > P > Mg > S and Fe >Mn> Zn > B > Cu.