Annual Datura accessions as source of alkaloids, oil and protein under Mediterranean conditions

Potentially, Datura species can turn to a multipotent crop providing alkaloids for pharmaceuticals, oil for non-edible uses and protein for livestock feed. In a two-year (2012-2013) field experiment, five Datura accessions (one D. stramonium f. stramonium, three D. stramonium f. tatula, and one D. ferox) were tested for alkaloid (atropine, scopolamine) concentration in aerial plant parts and seed oil (Oil) and protein concentration (Prot) and yield. Above-ground biomass was sampled 105 days after seeding (DAS) and in parallel leaf physiological traits were determined. Alkaloids were measured in stems, leaves, flowers, fruits and the alkaloid yield (the sum of the products of plant part weights with the respective alkaloid concentrations) were calculated. Leaves, consisting about 30% of the dry biomass, were the most enriched in both alkaloids, followed by flowers; in contrast, stems were depleted with some accessions having very low to nil concentrations. In general, D. ferox had the lowest concentrations. Accessions did not differ in scopolamine yield but D. stramonium accessions outstripped D. ferox in atropine yield; no significant differences in atropine yield were found among D. stramonium accessions. Growing season affected significantly alkaloid concentrations and yields; wet and cool 2013 decreased them detrimentally. About 150 DAS, harvest took place to estimate seed yield (SY), 1000-seed weight, Oil and Prot. Seed yield, Prot and protein yield (PY) were favored by wet and cool conditions in 2013; in contrast, Oil and oil yield (OY) were plummeted. With the exception of CO2 assimilation rate and stomatal conductance, leaf physiological traits were affected by growing season but only carbon isotope discrimination (Δ) and leaf N concentration differed between accessions. High-yielding accessions had higher Δ indicating that SY were controlled by water uptake and transpiration. Accessions of f. tatula had the highest Oil (>12%) but no genotypic differences were found for Prot; the large-seeded D. ferox had the highest SY and PY. Accessions of f. tatula were larger-seeded than f. stramonium. Concluding, growing season conditions controlled Datura qualitative traits and the respective yields. Variation among accessions can be exploitable.