Abstract
The species Ocimum gratissimum L. is widely utilized in food, cosmetics, and folk medicine, and is also an important source of essential oils. Understanding its behavior in response to environmental conditions is of paramount importance to improving crop management methods. In this context, the following study aimed to evaluate the effects of shade, and of competition with weeds (Cyperus rotundus L.), on the growth of Ocimum gratissimum L. The experimental design adopted was randomized blocks, in a 5 × 5 factorial scheme, with 5 levels of shading (48%, 75%, 77%, 83% and 90%) and 5 densities of Cyperus rotundus L. (0, 5, 10, 15 and 20 per pot), with 4 repetitions. The variables analyzed were main stem height (MSH), diameter of stem base (DSB), number of leaves on the principal branch (NL), number of ramifications (NR), chlorophyll index of leaves (CIL), foliar area (FA), dry mass of the aerial part of the medicinal species (DMAPm), dry mass of the aerial part of the weed species (DMAPw) and essential oil content (EOC). The results demonstrate that the Ocimum gratissimum L. plants presented compatible tolerance responses to up to 70% shading, and that competition with Cyperus rotundus L. was detrimental in a density above 13 plants per pot in interaction with shading. The highest dry mass production and, consequently, the highest oil yield, were obtained from the 48% shading treatment.
Highlights
The species Ocimum gratissimum L., commonly known as clove basil, African basil, or wild basil, is an aromatic subshrub native to Asia and Africa, and is subspontaneous in all Brazilian territory
Exsiccate from the Ocimum gratissimum L. was deposited in the Darcy Ribeiro herbarium of the Universidade Estadual do Norte Fluminense (UENF), in Campos dos Goytacazes, under registration HUENF 10457
It is observed that the main stem height (MSH), diameter of stem base (DSB), number of leaves (NL), number of ramifications (NR), chlorophyll index of leaves (CIL), and foliar area (FA) variables of Ocimum gratissimum L. were affected by the shade levels
Summary
The species Ocimum gratissimum L., commonly known as clove basil, African basil, or wild basil, is an aromatic subshrub native to Asia and Africa, and is subspontaneous in all Brazilian territory. It contains numerous compounds, primarily eugenol, that are likely responsible for its antimicrobial activity (Oliveira et al, 2016). As a primary energy source for photosynthesis and morphogenetic phenomena, is a major factor in plant growth and development, which are further affected by the intensity, direction, duration, and quality of the light (Corrêa et al, 2012) Competing with another species for light and other resources will activate a plant’s defense mechanisms, altering the secondary metabolism. One such response is increasing allelochemical production and releasing them into the environment, which affects the sensitive recipient plant’s growth and development (Shah et al, 2016)
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