Saffron is a valuable plant and one of the most expensive spices worldwide. Nowadays, there is a tendency to produce this crop in indoor plant production systems. However, the production of saffron is restricted by the need for the reproduction of high-quality corms. In this study, we investigated the effect of different ratios of red (R) and blue (B) light spectra (including 100% B (monochromatic B), 75%, 50%, 40%, 25% B, and 0% B (monochromatic R) on the photosynthetic performance and biomass partitioning as well as morphological and biochemical characteristics of saffron. The growth of flower, root, and corm was improved by increasing the proportion of B to R light. B-grown plants were characterized by the highest photosynthetic functionality with efficient electron transport and lower energy dissipation when compared to R-grown plants. B light directed biomass toward the corms and floral organs, while R light directed it toward the leaves. In saffron, the weight of a daughter corm is of great importance since it determines the yield of the next year. As the ratio of B to R light increased, the daughter corms also became heavier, at the cost of reducing their number, though increasing the proportion of B-enhanced antioxidant capacity as well as the activity of ascorbate peroxidase and catalase while superoxide dismutase activity was enhanced in R-grown plants. In conclusion, B light increased the production of high-quality daughter corms and altered biomass partitioning towards harvestable organs (corms and flowers) in saffron plants.

Peppermint is one of the most important and commonly used medicinal and aromatic plants worldwide. Present experiment was conducted to evaluate the essential oil content and quantitative changes of the main components of peppermint plants at different stages of crop growth. Greenhouse pots with peppermint Plants (30, 60 and 90 days after transplanting) were subjected to three different field capacity (FC) irrigation conditions, i.e. no stress, mild stress (60±5 % FC) and moderate stress (40±5 % FC) for one month. Essential oil composition and accumulation in peppermint was differentþ by plant growth stage alterations. The proportions of some monoterpene such as menthofuran, limonene, and pulegone decreased as plant matured, while those of menthol, cineole, and neomenthol increased. Both mild and moderate water stresses changed the essential oil content. Essential oil content of plants subjected to mild stress increased while moderate water stress treatment caused a significant reduction in essential oil content in different plant growth stage. Moderate stress reduced the essential oil percentage and changed the essential oil profile. Menthone content decreased and menthofuran content increased under moderate stress. Also, relative proportions of sesquiterpenes increased with water stress.

Peppermint (Mentha × piperita L.) infusion is one of the main important sources of antioxidants. This antioxidant property can be enhanced by using elicitors and inducing abiotic stress. This study was conducted to evaluate the foliar application of Methyl Jasmonate (50 µM) and water deficit stress (no stress, mild stress and moderate stress as 100, 75 and 50% of field capacity, respectively) and their interactions on cultivated peppermint on plant growth, secondary metabolite and antioxidant capacity of infusions made under different treatment. Water deficit stress treatments increased flavonoid contents and total phenolic as well as antioxidant capacity significantly. Some phenolic compound such as luteolin, naringenin, coumaric acid, and quercetin were detected only in some drought and Methyl Jasmonate treatments. Also, fewer amino acids such as L-serine, Threonine, 4-aminobutiric acid, 5-oxo-L-proline and unsaturated fatty acids were identified. Also, foliar application of 50 µM Methyl Jasmonate treatment improved plant growth parameters and metabolite profile such as carbohydrates and amino acids in non-stress and stress conditions. Therefore, inducing water stress and applying MeJA is recommended to enhance the biologic properties of peppermint and improve bioactive compounds and the antioxidant capacity of peppermint infusions.