A preliminary study on heavy metal monitoring in soil and guar (Cyamopsis tetragonoloba) biomass amended with sewage sludge.

Applying sewage sludge in agricultural soils is an interesting source of organic matter. This study aimed to monitor concentrations of heavy elements in soil and guar plants, which can pose a risk to the health of humans and animals if they enter the food chain through the soil-plant system. The experiment revealed that applying sludge increased the amount of organic matter, total nitrogen, potassium, and phosphorus in the soil. Additionally, the concentration of heavy metals such as Pb, Co, Cr, Ni, Cu, and Zn in all treatments remained below the permissible limits for soil. The highest plant height and plant dry weight were recorded in the sludge and sludge + fertilizer treatments. The dry weight of the guar varied from 629 g m-1 in the control treatment to 1050 g m-1 in the sludge + fertilizer plots. The use of sludge increased the accumulation of heavy metals in the above-ground parts of the guar plant compared to the control. However, the level of heavy metal remained within the normal range and below the toxic concentration. Our results also showed that the application of sludge along with fertilizer improved the quality of the guar forage by increasing the levels of crude protein, digestible dry matter and water-soluble carbohydrates. Overall, the results indicated that using sludge as organic fertilizer can improve soil properties, reduce the use of inorganic fertilizers, and decrease the harmful effects of heavy metals on the environment and health in the research area.

Expression profiling of rosmarinic acid biosynthetic genes and some physiological responses from Mentha piperita L. under salinity and heat stress.

Peppermint is of great economic importance, mainly due to its valuable essential oils. The present study aimed to compare the expression level of genes coding for proteins involved in the rosmarinic acid biosynthesis pathway and some physiological responses in peppermint under three levels of salinity (0, 60 and 120 mM) and two levels of thermal stresses (at 25 °C, optimal plant heat, and 35 °C, for thermal stress). The results showed that salinity at 25 °C resulted in an increased relative level of phenolic compounds, proline and antioxidant activity by 1.88, 1.92 and 2.58 times after 72 h respectively at salinity of 120 mM. Rosmarinic acid as well as soluble sugar, chlorophyll and K+/N+ ratio showed a decreasing trend by 3.2, 1.8, 4.6 and 9 times after 72 h respectively at salinity of 120 mM at 35 °C. Gene expression analysis showed a significant increase in HPPR and C4H expression and a significant decrease in RAS expression in plants subjected to simultaneous stresses. The higher levels of C4H and HPPR expression indicate the roles of these genes in defense processes and the effects of phenolic compounds in inhibiting oxidative stress. Our results may help increase knowledge about the stress-dependent alterations in gene expression profiles and physiological patterns in plants. This information may be used for medicinal plant improvement programs aimed at increasing rosmarinic acid production.

Amendment with halophytes and wind deposit allow subsequent cultivation of sorghum on a saline-sodic soil in the arid region of Yazd (Iran).

Aridity and salinity limit sustainable biomass production and agricultural practices in desert areas. The capability of halophytes plantation with wind deposits containing around 10% gypsum was evaluated for reclamation of saline soil and its effect on the production of Sorghum bicolar L., in an arid area. Two substance treatments at concentrations of 25 and 50 ton ha-1 gypsum and wind deposits at levels of 85 and 170 ton ha-1 were applied. Biological treatments were applied using halophyte plantation as a pioneer species. Sorghum was cultivated for all substance treatments and the production of sorghum was determined for the different treatments. Results indicated that the method leads to a reduction of salinity from 139 to <4 dS m-1 and SAR declined from 129.6 to 6.2 after a period of 15 months. The performance of wind deposits used in these experiments was higher than pure gypsum to reclaim saline soils. Maximum production of sorghum has been obtained by the treatment of 85 ton ha-1 wind deposit. Results indicated land reclamation and biomass production of forage seems possible when using wind deposit in the study area and therefore the wind deposit can effectively be used for reclamation of saline soil and plant production in arid environments.

This study evaluated the efficiency and environmental benefits of halophyte plantations incorporated with wind deposits resulting from wind erosion for saline-sodic soil reclamation. This approach illustrated the capability of the method as an eco-friendly and inexpensive method for biomass production in arid regions for the first time. The appropriate halophyte plants and optimum amount of wind deposit were evaluated in comparison to gypsum amendment for saline-sodic soil reclamation and biomass production.

Fast quality assessment of German chamomile (Matricaria chamomilla L.) by headspace solid-phase microextraction: influence of flower development stage.

For an adequate quality evaluation of aromatic plants grown under different conditions, a rapid, simple and sensitive method for the analysis of volatile constituents is indispensable. The main objective of the present study was to compare fast screening of German chamomile (Matricaria chamomilla L.) by means of headspace solid-phase microextraction (HS-SPME) with conventional isolation of the essential oil (steam distillation-solvent extraction (SDSE)) for the differentiation of chamomile essential oil constituents. Flowers were harvested at two distinct development stages: stage I, when ligulate flowers start to develop and tubular flowers are still closed, and stage II, when tubular flowers are partially to completely opened. Dried chamomile flowers at two development stages were extracted by means of both SDSE and HS-SPME, followed by GC-MS analysis. Among 30 compounds detected, (E)-beta-farnesene (49%), artemisia ketone (10%) and germacrene D (9%) were the predominant volatile components in the HS-SPME-extract, while alpha-bisabolol oxide A (42%), chamazulene (21%) and (Z)-spiroether (8%) were the main essential oil constituents among the 13 compounds obtained by SDSE. After statistical analysis of the data, both techniques enabled the same conclusion: (E)-beta-farnesene was the only compound which showed significant differences between the two flower development stages. These results suggest that HS-SPME-GC-MS can be used as a sensitive technique for the rapid screening and quality assessment of M. chamomilla.