Alessandra Carrubba

Sustainable production of fennel and dill by intercropping

Intercropping is claimed to be one of the most significant cropping techniques in sustainable agriculture, and much research and many reviews attribute to its utilization a number of environmental benefits, from promoting land biodiversity to diversifying agricultural outcome. In this sense, intercropping is thought to be a useful means of minimizing the risks of agricultural production in many environments, including those typical of under-developed or marginal areas. In order to validate this hypothesis in a representative area of the semiarid Mediterranean environment, we evaluated the possibility of growing dill and fennel, both belonging to the family Apiaceae, in temporary intercropping. Our trial was performed in Sicily in 2000–01 and 2001–02; in the first year, fennel and dill were cultivated in a mixture using a substitution scheme, whereas in 2001–02 we evaluated the bio-agronomical and chemical features of fennel alone. The biological efficiency of the intercropping system was evaluated by using the Land Equivalent Ratio and the Competitive Ratio, and an estimate of the interaction effects of both crops was performed by analyzing the major vegetative and yield traits of plants, along with the chemical profile of volatiles of the fruits. Both in grain yield and in biomass yield, the most efficient cropping system was the intercropping ratio with a higher proportion of fennel, in which the competitive ratio values calculated for dill reached 1.90 for grain and 2.59 for biomass. Our results also indicate that the presence of dill exerted a clear stabilizing effect on fennel seed yield of the following year: whereas no difference in fennel seed yield was detected from one year to the following on the previously intercropped plots, in the repeated pure stand a 50% yield reduction was recorded. In the trial environment, the technique showed a good potential to improve the efficiency of resource utilization; further long-term experiments will be necessary in order to demonstrate the application of such a technique to other medicinal and aromatic plant mixtures.

Statistical Analyses on the Essential Oil of Italian Coriander (Coriandrum sativum L.) Fruits of Different Ages and Origins

Abstract Thirty-one samples of Coriandrum sativum L. fruits, of different origin, year of cultivation (harvest) and crop management systems were subjected to volatile component analysis by combining Head Space Solid Phase Microextraction (HS-SPME) with GC/MS. In order to determine the importance of the major sources of volatile variability, some statistical analyses, including Cluster Analysis (CA) and Principal Component Analysis (PCA), were performed on the obtained data. The compounds, which gave the main contribution to the partition and classification of the original data, were α-pinene, p-cymene, γ-terpinene and linalool. The age of the fruits, which ranged from 1–16 years, seemed to generate rather identifiable effects such as a decreasing trend on α- and γ-terpinene, terpinolene and linalool, and an increase in p-cymene. The same components also seemed to vary depending upon the geographic location of the cultivation. No statistically relevant differences were detected between the biological and conventional cropping management techniques.

The scent of Mare Nostrum: medicinal and aromatic plants in Mediterranean soils

In the Mediterranean area, the simultaneous occurrence of pedological, climatic and economic constraints often sets a limit on the profitability of agriculture, and farmers are forced to grow a reduced number of species, dealing with a secure-albeit low-market income. The introduction of medicinal and aromatic plants (MAPs) inside the current farming systems could represent a useful means to meet the multifunctional role of agriculture: producing safe food, in respect of the environment, and contributing to the development of rural areas. The study of the relationships between MAPs and the soils in which they may be grown may have two approaches: (1) the evaluation of yield and qualitative response of MAPs to the variation of soil features; and (2) the study of selective recovery of certain elements (toxic and beneficial), and their subsequent release in herbal products. In many MAPs, significant variations of plant characteristics have been ascertained with varying soil traits, and the selective recovery and subsequent release in food of certain elements have been demonstrated. Hence, great attention must be paid to the choice of soil and cropping strategies, to obtain satisfactory yields of high quality and best-priced products, respecting their safety and nutritional value.

Essential oil crops for sustainable agriculture - A review

Multifunctionality and diversification of farming systems, integration of agricultural practices with the non-agricultural productive systems operating on the territory, biodiversity safeguards, and reduction in off-farm inputs, are key factors for all modern development strategies in agricultural areas. Such issues are valid worldwide, but are especially true in areas in which the cultivation of the more widespread and “classical” crops is constrained by factors of varying degree and importance. In Mediterranean areas, where many environmental and economic factors often reduce rural areas to marginal conditions, the search for new crop opportunities has become one of the newest topics in agricultural research. In this review, we focus on the state-of-the-art cultivation of essential oil crops, in Mediterranean environments with a special interest in herbs. The following are the major points of our analysis. (1) Growing such crops as specialized cultivations, especially for species native to the selected environments, is the only practical and sustainable way to obtain naturally derived raw matter for both industrial and domestic purposes. (2) Most essential oil crops are suitable for many different uses, and fully adaptable for transformation even by small, local manufacturers. (3) In many cases, they may be grown with environmentally friendly or organic techniques; this enhances their environmental compatibility and also gives them an additional economical advantage, raising their chances to be addressed in the emerging market sector of “natural” products. Our conclusion is that crops grown for the extraction of economically valuable essential oils may be a strategic resource for many environments, even marginal, and that there is scope for farmers to improve the cultivation of such species on arable land. There is room, however, for many agronomic and economic questions to be studied in future experimentation and research.

Artemisia arborescens L.: essential oil composition and effects of plant growth stage in some genotypes from Sicily

Essential oils from aerial parts of several Artemisia arborescens L. populations, collected in five different localities of Sicily, were analyzed by gas chromatograph–flame ionization detector (GC–FID) and GC–mass spectrometry (GC–MS) in order to study the chemical composition and its variability due to phenological stage. Forty-three compounds, accounting for more than 92% of the oil, were identified. Monoterpene fraction with the exception of Petru population was higher than the sesquiterpene fraction. β-Thujone (20.5–55.9%), chamazulene (15.2–49.4%), camphor (1.3–10.7%) and germacrene D (2.3–3.4%) were the main compounds. Chemical composition was influenced by phenological stage, with an increase in the monoterpene fraction at flowering stage; both in flowering and vegetative stages, the main compounds were always the oxygenated monoterpene β-thujone and the sesquiterpene hydrocarbon chamazulene.

Arbuscular mycorrhizal fungi altered the hypericin, pseudohypericin, and hyperforin content in flowers of Hypericum perforatum grown under contrasting P availability in a highly organic substrate

St. John’s Wort (Hypericum perforatum) is a perennial herb able to produce water-soluble active ingredients (a.i.), mostly in flowers, with a wide range of medicinal and biotechnological uses. However, information about the ability of arbuscular mycorrhizal fungi (AMF) to affect its biomass accumulation, flower production, and concentration of a.i. under contrasting nutrient availability is still scarce. In the present experiment, we evaluated the role of AMF on growth, flower production, and concentration of bioactive secondary metabolites (hypericin, pseudohypericin, and hyperforin) of H. perforatum under contrasting P availability. AMF stimulated the production of aboveground biomass under low P conditions and increased the production of root biomass. AMF almost halved the number of flowers per plant by means of a reduction of the number of flower-bearing stems per plant under high P availability and through a lower number of flowers per stem in the low-P treatment. Flower hyperforin concentration was 17.5% lower in mycorrhizal than in non-mycorrhizal plants. On the contrary, pseudohypericin and hypericin concentrations increased by 166.8 and 279.2%, respectively, with AMF under low P availability, whereas no effect of AMF was found under high P availability. These results have implications for modulating the secondary metabolite production of H. perforatum. However, further studies are needed to evaluate the competition for photosynthates between AMF and flowers at different nutrient availabilities for both plant and AM fungus.

Sustainable Weed, Disease and Pest Management in Medicinal and Aromatic Plants

As for all other crops, in MAPs as well, weeds, diseases and pests are important yield-reducing factors, which may severely curtain biomass production and, that is maybe more important, may affect several qualitative aspects of production. Research about this topic is generally lacking, for two main reasons: the first is that MAPs are generally grown on rather limited areas, and the incidence of specific pests and diseases rarely takes a relevance outside rather narrow boundaries. The second reason is that the economical importance of MAPs is much lower than that ascribed to the “major” crops, which the bigger efforts of research are addressed to. In the changing scenario of latter years, however, MAPs are taking an increasing relevance, and there is the necessity to draw proper guidelines for their cultivation technique, also including the advisable strategies for their sustainable protection.

Variations in the Volatile Compounds of a Fennel (Foeniculum Vulgare Mill.) Variety Grown in a Semi-Arid Mediterranean Environment

Abstract Fennel is an industrial source of anethole but, recently, further interest has came from the suggested possibility of many industrial uses of this plant.The volatile substances from the seeds of Fennel grown in Sparacia (Cammarata – AG – Sicily; 37° 38’ N; 13° 46’ E) have been investigated and compared on a statistical base with previously reported data. The variety grown in Sparacia fall into the “high fenchone” chemovariety. The substances α-toluene, α-terpinene, β-phellandrene+limonene and camphene appear the components most sensitive to environment and grow condition modifications.

Sustainable Fertilization in Medicinal and Aromatic Plants

The nutrient level in the soil is one of the most investigated aspects of agricultural research, also including research into Medicinal and Aromatic plants. The effect of fertilization has been studied in detail for many species, with contrasting results as concerns above all the qualitative aspects of production. Generally speaking, an increased level of nutrients induces an enhancement of plant biomass, but when the goal of cultivation is different from herbage yield, i.e. when a special plant part (seeds, or roots, or flowers) is of interest, or when the quality features are especially important, the outcome of fertilization may be dramatically different. A fine-tuned fertilization practice is therefore necessary, and forms, rates and times of distribution of fertilizers must be accurately planned and managed.

Weed and Weeding Effects on Medicinal Herbs

Competition with weeds exerts significant depressive effects on yield and quality features of Medicinal Plants (MPs). According to the crop, the part of plant to be harvested, the environmental features (including cropping technique) and the severity of infestation, yield losses due to the presence of weeds may vary within wide intervals. Furthermore, unlike the majority of other crops, MPs are cultivated with the goal to obtain relevant quantities of specific secondary metabolites, whose final quantity determines the quality level (and, consequently, the market value) of the harvested drug. Almost all papers addressed to this topic agree on the statement that unrestricted weed growth may alter MP production also from the qualitative point of view, that is, determining an overall decrease in the yield of active substances for unit area. In part, this outcome can be attributed to the general decrease of harvestable biomass, but in some cases also modifications of crop metabolic pathways have been observed, resulting in a general unpredictability of the chemical characteristics of the product obtained in weedy fields. Competition with weeds may assume a different severity according to the time and duration of competition period. In the starting phases of cultivation, the outcome of an early weed infestation is expected to be severe, since very often weeds grow much faster than crops. The maximum tolerance period, i.e. the period when weeding operations must be started, varies according to the tolerated loss values, and in annual crops the time span when fields must be kept totally weed-free may cover more than 60% of the entire crop cycle. The tools that are used for weeds removal may affect MPs production in many ways. Chemical treatments have been studied with contrasting results, but an interference of herbicides with the metabolism of secondary products was found in some cases. Furthermore, the interest in growing MPs with organic or environmentally friendly methods is increasing. Hence, besides the traditional (and highly expensive) method of hand-weeding, other non-chemical methods are studied, including mechanical treatments, mulching, flaming, and even grazing by goats or lambs. There is scope for further research, embracing a larger number of MPs and different environments, also including the effects of weeds on MPs metabolic pathways.