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IntroductionThe ever-increasing tendency to the use of medicinal plants in the world has grown concerns about their cultivation and production processes. As medicinal plants are more compatible with the nature, special interest and attention has recently been given to herb therapy, and use of medicinal plants, being limited by the rise of pharmaceutical drugs, has become again common and widespread due to a number of reasons. Nigella sativa L. is one of the herbs that has a variety of uses and has been being used in iran’s traditional medicine since old times. Today this plant is considered as one of the most important kinds of medicine. Therefore, it is of great importance to conduct some researches on the herbs around the country due to different ecological requirements. N. sativa belonging to buttercup family, with the scientific name of Ranunculaceae, is an annual, dicotyledonous, herbaceous plant. In several studies, N. sativa has been reported to have anti-oxidative, anti-inflammatory, strengthening of immune system, and anti-histamine and oil extract properties. Furthermore, several effects such as lowering blood sugar, lipids, and hypertension, excretion of bile and uric acid, protection of liver, kidney and cardiovascular tissues as well as anti-seizure, anti-cancer, anti-microbial and anti-parasitic effects related to this plant have been reported. The aim of the present study is to improve the yield and yield components and oil of medicinal plant N. sativa by anti-transpiration compounds under drought stress conditions. Materials and MethodsAn experiment was conducted at Research Station,Faculty of Agriculture, Ferdowsi University of Mashhad, in 2012-2013. The research was performed using a split plot experiment based on a randomized complete block design with three replications. The irrigation intervals (8 and 16 days) in main plots and anti-transpiration compounds of chitosan (0.25, 0.5 and 1%), Plantogopsyllium mucilage (0.5, 1 and 1.5%) and arabic gum (0.25, 0.5 and 0.75 %) were put in subplots with three replications. Also, the distance between the main plots in each block and distance between the two blocks were assigned as 100 cm and 200 cm, respectively; so that the moisture content of a plot had no effect on the adjacent plots. Planting date was April16 and planting was performed by hand in 0.5cm-deep furrows. Throughout the growing season, anti-transpiration compounds were applied concurrently with the imposition of drought stress, administered weekly at sunset until the flowering stage. Subsequently, yield, yield components, and oil content were measured. Results and Discussion Results showed that irrigation intervals had significant effects on all studied characteristics with the exception of 1000 seed weight. ncreasing irrigation intervals reduced percentage yield and yield components and oil of black cumin grains. Anti-transpirants compounds did have significant effects on percentage of oil and yield and yield components of black cumin grains. There were significant difference between different anti-transpirants compounds in terms of oil and yield components yield and of black cumin grains. The 8 days irrigation interval produced more grain yield compared with 16 days irrigation intervals (621.56 vs. 484.23 kg/ha). The highest oil (27.74%) and lowest (21.74%), respectively, at treatment anti-transpirants compound chitosan1 percent With 8 days irrigation interval and gam arabic 0.25 percent was obtained with 16 days irrigation interval and chitosan stimulating abscisic acid synthesis in the treated plant would result in stomatal closure, reduction of stomatal conductance, transpiration rate and water content. They also pointed out that the anti-transpiration effect of chitosan was because of its stimulatory effect in increasing abscisic acid concentration in the treated leaves of bean plant. As the above compounds are natural and biodegradable, as well as safer and less expensive than other chemical anti-transpiration compounds, they can serve as a good alternative to the chemical compounds. Cognition and expertise in water relations of plant and drought stress tolerance is considered as the main program in agriculture and the ability to withstand this stress is of great economic importance. Conclusion The anti-transpiration compounds led to significant changes in terms of all the studied traits compared to the control, indicating the effectiveness of theses natural compounds. Providing the appropriate conditions, 1% chitosan treatment can enhance the yield under drought stress. Spraying by arabic gum did not improve the growth conditions. According to this experiment, 1% chitosan treatment and 1.5% Plantago psyllium mucilage is considered the most appropriate strategy to enhance the yield of Nigella sativa under drought stress.

Introduction: Fresh-cut produce graduated to retail during the1990s, especially for lettuce, cabbage, carrots and other similar vegetables. The high microbial loads of these products after harvest can be substantially reduced through a cleaning in flowing chlorinated water and adistribution under ensured controlledrefrigeration. Therefore, a good number of convenient ready-to-use greens were launched to the market in the past decade. Nowadays, theuse of this technology to achieve similar results in fruit products is one of the most challengingtargets for processors. However, there is anumber of issues that still need to beovercomebeforefresh-cut fruit commodities can be sparked off to anoutstanding position in the segment of lightly-treatedrefrigerated foods. The importance of freshly cut products increases day by day. Tissue and cell rupture leads to a decrease in the shelf life of these products. On the other hand, these products due to increased enzyme activity, respiration rate and microbiological considerations that affect the health of these productsrequires highly attention.To increase the shelf life of the products and prevent undesirable changes in cut slices of fruit or vegetables a coating on the surface of these products has been suggested. Mucilages and essential oils of herbs are natural compounds that can be used to create such covers. The advantages of these coatings are their bactericidal effect, maintenanceof pleasant taste and other physical and chemical characteristics of the product and even decrease of environmental pollution. In this research, the effect of natural compounds such as Zataria multiflora essential oil (EO) and Plantagopsyllium mucilage on storage life and microbial load of fresh cut carrot was studied. Materials and Methods: The research was conducted in two separate experiments on fresh-cut carrot: In the first experiment, the effect of different concentrations of Plantago psyllium mucilage (0,100, 200, and 400mgL-1) and four concentrations of Zataria multiflora essential oil (0,100, 250,and 500 mgL-1), in a factorial experiment on the basis of completely randomized designwith16treatments and three replications was evaluated. In the second experiment application of essential oil and mucilage on microbial load of fresh-cut carrot was examined in a split plot experiment on the basis of randomized complete blocks design with six treatments and three replications which Zataria multiflora EO (500 mgL-1) and Plantago psyllium mucilage (400 mgL-1) was set as main plot and storage time was set as subplot. The serial dilution technique and cultivation in special culture media were used to determine the microbial load. Treated samples were then packaged in polyethylene trays (175mL) and were stored at 4°C. After10 days of treatment different parameters such as weight loss, total soluble solids (TSS), titratable acidity (TA), pH, color, organoleptic properties, the amount of skin whitening and microbial load were evaluated.Means were compared using LSD test at the significant 5% probability level. Results and Discussion: The results showed that the treatments had a significant effect on weight loss. Essential oil and mucilage treated samples with different concentrations and also a combination of the two had less weight loss than the control. Different concentrations of essential oil and mucilage individually significantly affected titra table acidity, soluble solids and pH. Samples treated with 100 and 250 mgL-1essential oil, and with 100 and 200 mgL-1 mucilage had the highest acidity, and showed significant increase compared to the control. A little color changes occurred in the treated samples and their colors were very close to the control. Combination treatment with 100 mg.L-1essentialoil plus 100 mgL-1mucilagesignificantlyreduced skin whitening of fresh cut carrot. Analysis of variance indicates significant effect of treatments on all microbial contaminations which were evaluated. The means of aerobic mesophilic bacterial contamination and the coliform bacterial contamination were 6.67 log CFU/g and6.37 log CFU/g, respectively. Only mold and yeast contamination significantly increased during storage and was more pronounced in samples treated with psylliummucilage. After 10 days of storage, although some bacterial contamination increased, this increase was not significant. Fungal contamination starts at 5.35 log CFU/g and endsat 6.64 log CFU/g, which is approximately 1.3 log CFU/g increased. E. coli contamination was not observed in samples.According to the standards threshold, in this experiment, aerobic mesophilic bacteria contamination of the samples (except for samples coated with mucilage after 10 days of storage which their contamination exceeded) was in the standard threshold.However, coliform bacteria, mold and yeast contamination in all samples exceeded. Conclusion: In general, results of this study showed that application of natural compounds of medicinal plants as edible coatings improved the quality and -extend the shelf life of fresh cut carrot. .However, disinfection of the product in this experiment was not sufficient to reduce the microbial contamination properly and treatments used could not reduce it at the standard limits, appropriate disinfection methods such as radiation and higher concentrations are also investigated in order to export this recommended product