Study the yield and quality of bitter gourd fruit (Momordica charantia) in inoculation with two species of mycorrhizal fungi and phosphorus fertilizer under different irrigation regimes.

Drought is known to be the most important constraint to the growth and yield of agricultural products in the world, and plant symbiosis with arbuscular mycorrhizal fungi (AMF) can be a way to reduce drought stress negative impacts. A two-year experiment to investigate the factorial combination of mycorrhizal fungi (Glomus mosseae, Glomus intraradices, Control) and phosphorus fertilizer (application and non-application of phosphorus) on fruit yield and phenolic acids changes bitter gourd under different irrigation regimes as a split factorial based on a randomized complete block design. Three irrigation regimes, including irrigation after 20%, 50%, and 80% available soil water content depletion (ASWD), were considered in the main plots. The results showed that under water deficit stress, fruit yield and physiological (photosynthesis rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), RWC, total chlorophyll, and root colonization) parameters decreased compared to 20% ASWD, and biochemical (proline, soluble sugar, MDA, CAT, SOD, phenol) parameters and fruit phenolic acids (caffeic acid, coumaric acid, ferulic acid) increased. However, the inoculation of AMF and phosphorus fertilizer in three irrigation regimes decreased MDA content, but physiological and biochemical parameters and fruit phenolic acids were increased. In this study, the factorial combination of AMF and sufficient phosphorus improved the resistance of bitter gourd to water deficit, and this not only improved fruit yield but also increased fruit phenolic acids under 80% ASWD, which can be an innovation in the management of water resources and the production industry of medicinal plants with high antioxidant properties in water deficit areas.

Investigation of yield, phytochemical composition, and photosynthetic pigments in different mint ecotypes under salinity stress.

Salinity stress is one of the main limiting factors of medicinal plant growth and may affect their characteristics and chemical composition. In order to evaluate the response of different species of Iranian mint to salinity stress, an experiment was designed in greenhouse conditions. In this experiment, six Iranian mint species were cultivated in pots under different salinity stress including 0, 2.5, 5, and 7.5 dS/m. The chlorophyll indices (a, b, total, and a/b ratio), carotenoids, total anthocyanin, total phenolic and flavonoid content, antioxidant activity, dry matter yield, and essential oil content were measured in two different harvest stages. Salinity stress affected various measured traits. The results showed that despite the negative effect of salinity stress on photosynthetic pigments, in some ecotypes and species, photosynthetic pigments were not affected by salinity stress. The amount of total phenolic content, total flavonoid content, and total anthocyanin increased in response to salinity stress. The dry matter decreased under salinity stress, but the content of essential oil increased as a result of salinity stress increment. The results of PCA biplot showed that the E16 and E18 ecotypes were separated by a large distance. Among the various ecotypes, E18 had the most desirable traits which can be recognized as a salt-tolerant ecotype. Also, piperita species was the best among the species in all salinity stress levels.

How to change the ratio of unsaturated (omega 3, 6, 7 and 9) to saturated fatty acids in Oenothera biennis L. oil under water deficit stress, fertilizers and geographical zones.

The 2015-2020 dietary guidelines for Americans advise substituting total unsaturated fatty acids (∑UFA) for total saturated fatty acids (∑SFA). Thus, field experiments were carried out to verify the influence of irrigation regime (well-irrigated and water deficit) and fertilizers (chemical and biological) on the ratio of ∑UFA to ∑SFA of evening primrose seed oil. Therefore, two experiments were conducted at the experimental stations (arid and semi-arid) of Iran in 2014 and 2015. Experiments were conducted in a split factorial layout within a randomized complete block design with three replications. Water deficit significantly reduced UFA (omega 3, 6, 7 and 9), ∑UFA and ratio of ∑UFA to ∑SFA (especially in the arid region), but it increased SFA and ∑SFA (especially in the arid region). In fact, fatty acid quality (increased ratio of ∑UFA to ∑SFA) of evening primrose seed oil was significantly increased in well-irrigated compared to water deficit stress (especially in the semi-arid region). Bio-fertilizers (Azospirillum lipoferum and Glomus mosseae) and chemical fertilizers (urea + triple superphosphate) increased the ratio of ∑UFA to ∑SFA of evening primrose seed oil (especially in the semi-arid region), but fatty acid quality of evening primrose oil was significantly increased in bio-fertilizers compared to the chemical fertilizers (especially in the arid region).

Effects of water stress and light intensity on chlorophyll fluorescence parameters and pigments of Aloe vera L.

Aloe vera L. is one of the most important medicinal plants in the world. In order to determine the effects of light intensity and water deficit stress on chlorophyll (Chl) fluorescence and pigments of A. vera, a split-plot in time experiment was laid out in a randomized complete block design with four replications in a research greenhouse. The factorial combination of three light intensities (50, 75 and 100% of sunlight) and four irrigation regimes (irrigation after depleting 20, 40, 60 and 80% of soil water content) were considered as main factors. Sampling time was considered as sub factor. The first, second and third samplings were performed 90, 180 and 270 days after imposing the treatments, respectively. The results demonstrated that the highest light intensity and the severe water stress decreased maximum fluorescence (Fm), variable fluorescence (Fv)/Fm, quantum yield of PSII photochemistry (ФPSII), Chl and photochemical quenching (qP) but increased non-photochemical quenching (NPQ), minimum fluorescence (F0) and Anthocyanin (Anth). Additionally, the highest Fm, Fv/Fm, ФPSII and qP and the lowest NPQ and F0 were observed when 50% of sunlight was blocked and irrigation was done after 40% soil water depletion. Irradiance of full sunlight and water deficit stress let to the photoinhibition of photosynthesis, as indicated by a reduced quantum yield of PSII, ФPSII, and qP, as well as higher NPQ. Thus, chlorophyll florescence measurements provide valuable physiological data. Close to half of total solar radiation and irrigation after depleting 40% of soil water content were selected as the most efficient treatments.

Effects of Azocompost and urea on the herbage yield and contents and compositions of essential oils from two genotypes of dragonhead (Dracocephalum moldavica L.) in two regions of Iran.

Dragonhead is an annual, herbaceous, balm-scented and spicy aromatic member of the family Lamiaceae. We examined effects of different sources of nitrogen on the content and composition of essential oils in two genotypes of dragonhead in two regions of Iran. The sources of nitrogen used were 100% urea (70 kg N ha(-1)), 75% urea (52.5 kg N ha(-1))+25% Azocompost (3.85 tonha(-1)), 50% urea (35 kg N ha(-1))+50% Azocompost (7.77 tonha(-1)), 25% urea (17.5 kg N ha(-1))+75% Azocompost (11.55 tonha(-1)), and 100% Azocompost (15.55 tonha(-1)). Optimal yield and content of essential oil at both locations for both genotypes were obtained by applying 50% urea+50% Azocompost. Geraniol, geranial, and geranyl acetate were the most abundant compounds. For both genotypes and both locations, application of 50% urea+50% Azocompost increased levels of geraniol and geranial, and application of Azocompost alone increased levels of geranyl acetate. Overall, we conclude that the application of 50% urea with 50% Azocompost is recommended for optimising the content and composition of essential oils in dragonhead.