Response of essential-oil yield of aromatic and medicinal plants to different harvesting strategies

The demand for aromatic and medicinal plants (AMPs) is growing worldwide, and most of them are from the wild collection. Today there is a consensus that for industrial purposes the AMPs must be cultivated. Many studies have shown the importance of the collection strategy used to guarantee the plant regeneration, and soil protection against erosion process in mountainous areas in the Mediterranean region. In this work, during three-year monitoring period we compared in four AMPs two harvest strategies by cutting biomass in 25% (BHI25) and 50% (BHI50) of oregano (Origanum bastetanum L.), lavender (Lavandula lanata L.); sage (Salvia lavandulifolia V.); and santolina (Santolina rosmarinifolia L.) in order to assess their effect on essential-oil content, and to be consistent with both plant and soil conservation in Mediterranean steeply sloping areas. The experimental plots were located in Lanjarón (Granada, SE Spain), on a 20% slope. According to the findings the strategy BHI50 of fresh herb of oregano, lavender, sage, and santolina produced essential-oil yield of 13.2 ± 1.74, 17.3 ± 1.69, 9.7 ± 5.21, and 10.8 ± 2.00 L·ha-1, respectively. Since significant differences were found between BHI25 and BHI50 strategies for harvest and distillation of aromatic plants, we recommend a rational harvest, leaving the 50% of the plant biomass in the field to avoid the soil degradation. In addition, with this rational harvest strategy encourages the sustainable AMP cultivation without significant alterations for essential-oil yields, and at the same time guaranteeing the regrowth, and conservation of them in its habitat. Therefore, encouragement local decision-making measures regarding environmental compatibility, social acceptability and economic viability in land use and management will be crucial. Otherwise, the inappropriate harvest of aromatic shrubs in mountain areas compromises land conservation.The demand for aromatic and medicinal plants (AMPs) is growing worldwide, and most of them are from the wild collection. Today there is a consensus that for industrial purposes the AMPs must be cultivated. Many studies have shown the importance of the collection strategy used to guarantee the plant regeneration, and soil protection against erosion process in mountainous areas in the Mediterranean region. In this work, during three-year monitoring period we compared in four AMPs two harvest strategies by cutting biomass in 25% (BHI25) and 50% (BHI50) of oregano (Origanum bastetanum L.), lavender (Lavandula lanata L.); sage (Salvia lavandulifolia V.); and santolina (Santolina rosmarinifolia L.) in order to assess their effect on essential-oil content, and to be consistent with both plant and soil conservation in Mediterranean steeply sloping areas. The experimental plots were located in Lanjarón (Granada, SE Spain), on a 20% slope. According to the findings the strategy BHI50 of fresh herb of oregano, lavender, sage, and santolina produced essential-oil yield of 13.2 ± 1.74, 17.3 ± 1.69, 9.7 ± 5.21, and 10.8 ± 2.00 L·ha-1, respectively. Since significant differences were found between BHI25 and BHI50 strategies for harvest and distillation of aromatic plants, we recommend a rational harvest, leaving the 50% of the plant biomass in the field to avoid the soil degradation. In addition, with this rational harvest strategy encourages the sustainable AMP cultivation without significant alterations for essential-oil yields, and at the same time guaranteeing the regrowth, and conservation of them in its habitat. Therefore, encouragement local decision-making measures regarding environmental compatibility, social acceptability and economic viability in land use and management will be crucial. Otherwise, the inappropriate harvest of aromatic shrubs in mountain areas compromises land conservation

Yield of new hemp varieties for medical purposes under semi-arid Mediterranean environment conditions

Under the effects of climate change new drought tolerant crops are imperative to introduce in irrigated agricultural areas of Mediterranean countries. In this sense, hemp (Cannabis sativa L.) represents an alternative in many semi-arid agricultural areas of Mediterranean basin because of its low water requirements and cost effectiveness when it is developed under non controlled conditions. The aim of this work was to evaluate the potential yield of five new hemp varieties (Sara, Pilar, Aida, Theresa, and Juani) cultivated under high tunnel conditions in a semi-arid Mediterranean area, and also to study the effect of plant density on active biomass production and cannabinoids biosynthesis (cannabidiol, CBD and cannabigerol, CBG) at different plant positions. The trial was conducted under plastic macro-tunnels during two seasons (2014 and 2015), from May to October. The agronomic response and the chemical profiles of the studied varieties were evaluated at the end of each season. Moreover, it was monitored the differentiation in terms of active biomass production and cannabinoids biosynthesis in different plant organ positions (at upper, medium, and lower). Additionally, during the second season, three different plant densities (PD1, 9,777; PD2, 7,333; and PD3, 5,866 plants· ha-1) were tested in order to define the the best of them for maximizing CBD and CBG productions. The findings highlighted significant differences in yield between cultivars within the CBD and CBG. Moreover, plant density was a determinant factor related to active biomass production and cannabinoids contents, PD3 representing a suitable strategy to maximize the cannabinoids production minimizing the requirements of rooted apical cuttings. These results allowed concluding that these new hemp cultivars together with the adopted agronomic practices in this experience would be very appropriate for CBD and CBG productions, being determinant to consider the plant density and the cultivar for both studied chemotypes.Under the effects of climate change new drought tolerant crops are imperative to introduce in irrigated agricultural areas of Mediterranean countries. In this sense, hemp (Cannabis sativa L.) represents an alternative in many semi-arid agricultural areas of Mediterranean basin because of its low water requirements and cost effectiveness when it is developed under non controlled conditions. The aim of this work was to evaluate the potential yield of five new hemp varieties (Sara, Pilar, Aida, Theresa, and Juani) cultivated under high tunnel conditions in a semi-arid Mediterranean area, and also to study the effect of plant density on active biomass production and cannabinoids biosynthesis (cannabidiol, CBD and cannabigerol, CBG) at different plant positions. The trial was conducted under plastic macro-tunnels during two seasons (2014 and 2015), from May to October. The agronomic response and the chemical profiles of the studied varieties were evaluated at the end of each season. Moreover, it was monitored the differentiation in terms of active biomass production and cannabinoids biosynthesis in different plant organ positions (at upper, medium, and lower). Additionally, during the second season, three different plant densities (PD1, 9,777; PD2, 7,333; and PD3, 5,866 plants· ha-1) were tested in order to define the the best of them for maximizing CBD and CBG productions. The findings highlighted significant differences in yield between cultivars within the CBD and CBG. Moreover, plant density was a determinant factor related to active biomass production and cannabinoids contents, PD3 representing a suitable strategy to maximize the cannabinoids production minimizing the requirements of rooted apical cuttings. These results allowed concluding that these new hemp cultivars together with the adopted agronomic practices in this experience would be very appropriate for CBD and CBG productions, being determinant to consider the plant density and the cultivar for both studied chemotypes

Dynamic of Carbon and Nitrogen Concentrations in the Decomposition of Leaf Litter of Subtropical Crops in Southeastern Spain

Litter decomposition is one on the main routes of energy consume in an ecosystem and one of the principal roles in nutrient cycling. On the other side, in the last decades, subtropical crops have expanded importantly along the coast of Granada (SE Spain). To evaluate the cycles a bag technique experiment was carried out by using mango leaves (Mangifera indica L.), cherimolia (Annona cherimola Mill.), avocat (Persea americana Mill.) and loquat (Eriobotrya japonica L.). The main objective of this work was monitoring the dynamic of litter decomposition of these crops leaves and the evolution of their contents in carbon and nitrogen in a Mediterranean subtropical climate context. Bags were buried and recovered at certain time periodically to evaluate carbon and nitrogen concentration as well as mass losses. The results of this study showed that farmers could benefit of the knowledge of nutrient dynamics in litter decomposition to improve soil organic matter in the long term and to incorporate nitrogen. In this sense, loquat and mango showed the highest nitrogen accumulation and as a consequence these types of litters could be used as organic soil amendments in the long term. Contrarily, cherimolia accumulated higher carbon amounts than the rest of the studied crops

Benefits of plant strips for sustainable mountain agriculture

Erosion degrades soil quality in agricultural ecosystems, thereby reducing the productivity of the land. Semi-natural vegetation and diverse cropping systems have been converted into monocultures with low tree densities, leaving the soil unprotected. We evaluated the association in soil- and water-conservation systems with production in traditional almond orchards and the beneficial impact of plant strips in mountainous agriculture. Soil loss, runoff and nutrient loss over a four-year period (2002–2005) were monitored in hillside erosion plots with almond trees under different soil-management systems: (1) non-tillage with sage (Salvia lavandulifolia L. subspecies Oxyodon) strips 3 m wide; (2) non-tillage with rosemary (Rosmarinus officinalis L.) strips, (3) non-tillage with thyme (Thymus baeticus L. Boiss. exlacaita) strips, and (4) conventional tillage on the south flank of the Sierra Nevada (Lanjaron) in south-eastern Spain. Also, the nut yield from almond trees, and the biomass from aromatic-shrub strips were measured. The erosion plots, located on a 35% slope, were 144 m$^{2}$ in area. The plant-cover strips, 3 m wide, ran across the slope. Our results show that the most effective treatment proved to be non-tillage with thyme strips, reducing the annual soil loss by 93% and runoff by 80%, with respect to conventional tillage. Non-tillage with rosemary strips reduced soil loss by 91% and runoff by 82%, with respect to conventional tillage, while these percentages were 69% and 51%, respectively, for non-tillage with sage strips. In addition, all the treatments as a whole, in comparison with conventional tillage, revealed that the plant strips were the decisive factor in the reduction of NPK losses by surface runoff. The average nut yield from non-tillage with sage strips, non-tillage with rosemary strips, non-tillage with thyme strips and conventional tillage during the study period was 2.4, 3.2, 3.8 and 4.5 kg tree$^{-1}$, respectively, and the essential oil yield from sage, rosemary and thyme strips was 5.0, 8.7 and 10.8 L ha$^{-1}$, respectively. The non-tillage with thyme strips decreased nutrient loading in surface waters and thus had a positive impact on the environment while simultaneously maintaining reasonable almond-production levels. Thus, the combination of orchard trees with shrubs provided a viable option to conserve soil and water in hilly areas with opportunities to increase overall land productivity as well as sustainable agro-environmental measures

Impact of deficit irrigation on fruit yield and lipid profile of terraced avocado orchards

International audienceAvocado (Persea americana Mill.) is a subtropical tree, particularly sensitive to either an excess or a lack of water. Understanding this balance is crucial to determine the optimum water supply and enhance crop productivity. The rising shortage of water resources in semiarid producing regions and the need for irrigation optimization call for sustainable water savings. A 3-year monitoring study with avocado cv. “Hass” tested sustained-deficit irrigation strategies supplying 33, 50 or 75% of the estimated crop water demand. They were compared with a control strategy supplying 100% of the estimated crop water demand. The leaf water potential, stomatal conductance, tree growth, yield and several fruit quality parameters were evaluated. The yield, tree growth and fruit size were significantly and proportionally lessened by deficit irrigation treatments. Over the study, the average yields amounted to 31.6, 38.3 and 43.8 kg tree−1 in the 33, 50 and 75% treatments respectively, which were significantly less than the yield of 47.5 kg tree−1 measured in the control. The 33% and 75% sustained-deficit irrigation treatments increased the omega 3 and omega 6 fatty acids as well as the unsaturated fatty acids (oleic); however, the 33% deficit irrigation treatment significantly reduced the yield, size and fruit weight. We consider, therefore, that approximately 25% of the irrigation water can be saved without adversely affecting the avocado tree performance in short and medium terms and we recommend implementing the 75% sustained-deficit irrigation strategy. Here we show for the first time the key role of redesigning irrigation strategies in Mediterranean areas, focusing on the benefits of sustained-deficit irrigation, which can save water, encourage water use efficiency and enhance fruit quality. In order to save water, it is critical and necessary to implement such novel water shortage strategies, at the affordable cost of reducing fruit yield while enhancing its quality