Sorghum is an important forage crop, and both quantity and quality of this crop are affected by drought stress. Accordingly, in order to investigate the effect of drought stress on quantity and quality of morpho-physiological traits, a split-plot experiment was conducted based on randomized complete block design with four replicates in Isfahan, Iran, during 2017 and 2018 crop seasons. Treatments were irrigation regimes with four levels (control, preventing irrigation at pollination, seed milky, and seed doughy stages) and three varieties of sorghum (Sepideh, Kimia, and Payam). The results showed that drought stress negatively influenced morphological and yield-related traits of sorghum, while its effect was positive on some quality-related traits such as total soluble carbohydrate, crude protein, and proline contents. According to the results, drought stress based on prevention of irrigation at doughy stage (representing moderate drought stress) caused inconsiderable reduction in sorghum yield. In addition, drought stress has effect on relationships between morpho-physiological traits in sorghum. Considering morphological and yield-related traits together with susceptibility (stress susceptibility index) and tolerance (geometric mean product) indices indicated that Payam variety is more proper to be used in both drought stress and non-stress conditions. Furthermore, both Kimia and Payam varieties were shown to be suitable varieties based on quality-related traits, but because of having low NDF Payam variety might be more suitable.

The adverse effects of abiotic stresses have always restricted oilseed crop production, particularly in arid and semi-arid regions. On the other side, global climate change has led us to adapt planting dates and select tolerant cultivars to encounter the new climatic conditions. To evaluate the effect of late-season drought stress under different planting dates on rapeseed cultivars, an experiment was conducted as a factorial split-plot based on randomized complete block design in Karaj region- Iran, during 2015-2017. Planting date and irrigation treatments were considered in the main plots as factorial and cultivars were placed in subplots. Two planting dates were regular date (October 7) (PD1) and late planting date (November 6) (PD2). Irrigation was also carried out at two levels of normal irrigation (NI) and irrigation interruption from flowering stage onwards (II). Experimental cultivars included ES Hydromel, ES Alonso, ES Darko, ES Lauren, and Ahmadi. According to the results, late-season drought stress and delayed planting date reduced leaf relative water content (LRWC), total chlorophyll content (TCC), proline (LPC), and grain yield (GY), and increased stomatal resistance (SR), canopy temperature (CT), and leaf soluble carbohydrates (CLS) in rapeseed cultivars. The highest grain yield (4505.6 kg ha-1) was obtained in NI conditions and PD1. Significant interactions of planting date, irrigation, and cultivar on LRWC, SR, and CLS traits indicated that the ES Hydromel was the most tolerant hybrid cultivar with the highest LRWC and the lowest SR and CLS levels compared to other ones in unfavorable conditions of late-season drought stress and delayed planting. To confirm these results, cluster analysis led to the formation of two clusters, where ES Darko, Ahmadi, and ES Lauren cultivars were placed in the sensitive cluster and ES Hydromel and ES Alonso cultivars were assigned to the tolerant cluster. Therefore, ES Hydromel can be introduced as a superior cultivar to be selected as a genotype that presents acceptable resistance under drought stress and late sowing in arid and semi-arid regions.

The global approach in agriculture is to reduce the use of chemical fertilizers and the supply of nutrients from available sources which are environmentally friendly. In order to evaluate the feasibility of tobacco products without chemical fertilizer inputs, this research was carried out as a factorial experiment based on a 3×2×2 randomized complete block design which included biochar applied at three levels (0, 4, and 8 t ha -1 ), mycorrhiza, and Azotobacter at two levels (with and without application) with four replications. According to the results, 4 t ha -1 biochar increased the dry yield by 22%, the relative water content by 6%, and the root length by 41% compared to the zero level. However, there was no statistically significant difference between the 4 and 8 t ha -1 application of biochar with regard to most traits. The application of mycorrhiza improved the leaf area index as well as the tobacco root length. Azotobacter significantly increased the root length and nicotine content. The tobacco yield in rain-fed conditions is lower than usual, therefore the combined use of biochar and these biofertilizers may be considered as a viable solution. With increasing interest in the use of environmentally friendly sources of fertilizers and in terms of economic considerations, the use of 4 t ha -1 of biochar along with mycorrhiza and Azotobacter achieved an acceptable yield.K e y w o r d s: bio-coal, biofertilizers, chemical quality, nicotine content, tobacco

Antibiotic contamination in aquatic environments, as well as its effects on non-target organisms, has recently come to the attention of researchers. In the current study, three dosages (1, 0.5, and 0.25mg/L) of five antibiotic groups were tested on the marine green microalgae T. chuii: quinolones, tetracyclines, penicillins, macrolides, and sulfanamides. As stress biomarkers, cell density, dry biomass, specific growth rate, and chlorophyll content were calculated. Tetracyclines, penicilines, and sulfonamide in all doses inhibited algal growth. Among Quinolones, Ciprofloxacin and Enrofloxacin stimulated green algae growth at all tested dosages, whereas 1mg/l of Levofloxacin and Nalidilic acid inhibited it slightly while the other dosages stimulated it. Similar results were obtained for Macrolides: all three Erythromycin dosages were toxic to T.chuii, while 1mg/L was not. Similar results were obtained for Macrolides: all three Erythromycin dosages were toxic to T.chuii; while 1mg/L of Tylosin stimulated algal growth, lower dosages inhibited it. As a result, antibiotic pollution may alter the aquatic environment not only by reducing or inhibiting the growth of one species, but also by stimulating the growth of others, resulting in ecological imbalance and, as a result, the food chain. Using specific antibiotics in specific dosages in microalgae farms, on the other hand, could increase biomass while decreasing microbial contaminations.

The present study was performed to evaluate the effect of mycorrhizal symbiosis and azotobacter with the application of biochar on tobacco growth parameters, yield and nicotine content under rainfed conditions for two growing seasons (2016-2017 and 2017-2018). The factorial experiment was performed based on a randomized complete block design with four replications and three factors including biochar at three levels (0, 4 and 8 ton/ha), mycorrhizal fungi and Azotobacter chroococcum each one at two levels (without and with application). Results showed that biochar application had a significant and positive effect on all evaluated parameters. However, there was no statistically significant difference between 4 and 8 tons per hectare of biochar in yield. Mycorrhizal symbiosis had a significant effect on relative water content. Application of azotobacter had a positive and significant effect on growth parameters, yield and nicotine content under rainfed conditions for two growing seasons (2016-2017 and nicotine content. The greatest effect of azotobacter with a 17% increase was on leaf nicotine content. Whereas tobacco dry yield in rainfed conditions is lower, the combined use of biochar and these biofertilizers can be considered a desirable solution. Then in terms of economic aspects, the use of 4 tons biochar per hectare along with the use of mycorrhiza and azotobacter to achieve acceptable yield while maintaining chemical quality in tobacco farms is recommended.