Cultivation of wild medicinal species: opportunities and constraints.

Abstract

In medicinal plants (MPs), the transition from “discovery” to “cultivation” stage involves a decreasing recourse to their collection from the wild, accompanied by an increasing interest in their suitability into agricultural or silvicoltural cropping systems. Collecting from the wild, although is surely the oldest method for obtaining MPs, allows to satisfy very limited needs and is hardly suitable to an industrial use, because: 1) gathering from the wild does not guarantee the quantitative and qualitative uniformity that nowadays are well defined requirements of the consumers. Spontaneous yields are difficult to quantify and sometimes may be overestimated, above all when random and unforeseen phenomena generate a lowering of natural stocks. 2) Specialized production allows to reduce the depletion of natural stands. 3) Cultivation allows to exploit uncommon or rare plant species, dealing with some pharmaceutical interest but not represented in the wild in a satisfactory amount. MPs have been scarcely addressed to breeding activity, and even when cultivated they show (as a result of their evolutive process) many traits typical to the wild species that represent crucial constraints to their agronomical exploitation. Among these: 1) an indeterminate growth habit, common to many MPs, that forces the plant to a continuous production of flowers and fruits; 2) seeds dehiscence, developed by plants in order to facilitate their dissemination; 3) a low competitivity in field towards other species (weeds). Does cropping technique influence, and to what extent, the yield response of MPs? Fertilization, tillering or irrigation generate modifi¬cations in the growth environment of plants; other cropping techniques cause variations in the temperature, photoperiod and moisture conditions; the elimination of all companion plants causes competition to shift from interspecific (typical of natural stands) to intraspecific (typical of field crops); with varying plant population, cultivation alters plant geometry, height and distribution of reproductive organs, with significant consequences as the marketable product is represented by seeds. In MPs, in which all qualitative and quantitative traits are extremely important, deeper and careful studies should be addressed to the choice of the most proper cropping technique.