نشریه روابط خاک و گیاه
پیاپی 47 (پاییز 1400)

In Iran, the consumption grain of quinoa (Chenopodium quinoa Willd.) due to its nutritional properties has increased. Due to the Quinoa's ability to grow under adverse conditions (such as drought), the total cultivation areas for this plant have increased. Climate change scenarios predict extended periods of drought and this has emphasized the need for new crops that are tolerant to these conditions. The aim of this study was to investigate the effects of irrigation management on physiological properties of quinoa Gize-1 cultivar under greenhouse condition. The experiment was done using pot planting based on a completely randomized design including 3 replications at Ferdowsi University of Mashhad (FUM) during 2018-2019. Treatments included four irrigation managements, i.e., full irrigation (FI), alternate partial root-zone drying (APRD), fixed partial root-zone drying (FPRD), and deficit irrigation (DI). Results showed that DI, FPRD, and APRD significantly decreased stomatal conductance (40.9, 33.3, and 20.7%, respectively) when compared to FI treatment. Similarly, the greenness index (28.3, 26.3, and 15.3%, respectively) and relative water content (RWC) (20.4, 21.1, and 12.8%, respectively) were reduced under DI, FPRD, and APRD irrigations management compared to FI. Conversely, proline content was increased under DI, FPRD, and APRD treatments (24.2, 30.5, and 17.9%, respectively) when compared to FI. Generally, APRD treatment recommended for the quinoa Giza-1 cultivar to produce an acceptable yield under greenhouse conditions.

Quinoa (Chenopodium quinoa Willd.) is a plant with high nutritional value and growth potential, thus has a proper production in adverse environmental conditions. However, the enhancement of plant growth in these conditions could be achieved by different approaches. The use of endophytic microorganisms such as Serendipita indica fungus may help plant growth, especially under salt-stressed conditions. In this research, an experiment was performed using a factorial completely randomized design with three replications in a sterile sandy loam soil under greenhouse conditions. Experimental factors included two levels of S. indica (inoculation and non-inoculation) and salinity levels of 1.47 (initial electrical conductivity of soil), 5, 10, 20 and 30 dS/m which prepared by sodium chloride solution. The results showed that the interaction effect of salinity and fungal inoculation was significant for all measured characteristics (P < 0.05) except for proline. The inoculation of S. indica was able to increase the fresh weight of quinoa shoot by 18.5, 15.0, 39.4 and 45.4% compared to the non-inoculated treatment at salinity levels of 1.47, 5, 10 and 20 dS/m, respectively. The inoculation caused an increase in shoot fresh weight by 18% at initial electrical conductivity (5 dS/m), while a marked increase (~41%) was observed in inoculated plants compared to the no fungus treatment at EC level of 20 dS/m. The fungus increased the root weight by 12.9, 20.1 and 31.5% at salinity levels of 1.47, 5 and 10 dS/m compared to the non-fungal treatment, respectively. Compared to the non-fungal plants, the electrolyte leakage was significantly reduced in the inoculated plants at 10 dS/m. Fungal inoculation had pronounced effect on relative water content (RWC) of leaf at 5 dS/m and increased RWC by 23%, compared to the non-fungus treatment. Moreover, the increasing of salinity stress up to 30 dS/m reduced the percentage of root colonization by 19.9% compared to the non-fungus control. Overall, the application of S. indica significantly increased the biomass production of quinoa under salinity stress conditions.

Salinity is one of the most common abiotic stresses that affects growth and secondary metabolism in medicinal plants. In this study, the effects of two times foliar application of nano titanium dioxide on some agronomic traits of ajowan (Carum copticum) under salinity stress was investigated in a pot experiment. This study was conducted as a factorial experiment with completely randomized design and three replications. The factors included three levels of salinity (0, 50, and 100 mg L-1) and 5 concentrations of TiO2 nanoparticles (0, 10, 20, 40, and 80 mg L-1). Salinity treatments were implemented by adding NaCl to irrigation water of pots containing clay soil three times per week. The results showed that long-term irrigation with slightly saline water significantly decreased dry matter yield, height, total chlorophyll, weight of 100 seeds, number of seeds per plant, and seed yield and increased lipid peroxidation and the activities of catalase ( CAT ) and peroxidase (POX). Impact of 50 mg L-1 salt was not significant on essential oil percentage and essence yield; but 100 mg L-1 salt significantly (33.1%) decreased essential oil content. Foliar spraying of plants with 20 and 40 mg L-1 nano titanium dioxide had the most positive impact on growth and seed yield and significantly lowered lipid peroxidation via enhancing the activities of antioxidant enzymes under salt stress. Foliar spraying with 40 mg L-1 nano titanium dioxide significantly improved essential oil concentration (43.3%) and total essential oil yield (59.7%) under 100 mg L-1 salinity condition. The effect of foliar spraying with 80 mg L-1 nano titanium dioxide on some of the measured attributes was less than the impact of applying 20 and 40 mg L-1 nano titanium dioxide. These results suggest that foliar application of nano titanium dioxide with appropriate concentration improves salt tolerance, seed yield and essential oil content in ajowan.

The present study was conducted with the aim of symbiotic integration of Cyprinus carpio and five species of mint in the aquaponics system. The experiment was performed as a split plot design in time. Mentha species including Mentha aquatica, Mentha pulegium, Mentha spicata, Mentha suaveolens and Mentha piperita were considered as the main plot and harvest times (first and second) were used as sub-plots. The highest leaf number, internode length, number of stolon and leaf area were belonged to M. aquatica. On the other hand, M. aquatica, M. piperita and M. pulegium showed the highest shoot dry weight and stem diameter, while, the highest dry weight of stem and plant height were obtained in M. pulegium. The highest leaf/stem ratio was also observed for M. suaveolens, M. spicata and M. aquatic, respectively The highest relative water content (RWC) was related to M. piperita, which was not significantly different from those of M. aquatica, M. spicata and M. suaveolens. The highest greenness (SPAD) index was obtained in M. aquatica and M. piperita. Almost all of the studied traits including leaf fresh weight, stolon fresh weight, shoot fresh weight, leaf number, plant height, number of stem, leaf area, RWC and SPAD index were higher in the second harvest of mint species. Overall, M. aquatica and M. piperita showed a better performance than other species in terms of most of the studied traits and may be recommended for cultivation in the aquaponics system.

Heavy metals, as a limiting factor, affect plant physiological characteristics. Heavy metals toxicity leads to poor seed germination and limited plant growth. The effect of heavy metal lead (Pb) at six concentrations was investigated on morphological and biochemical traits of Bellis perennis in a completely randomized design experiment with five replications. Also, the ability of lead absorption by B. perennis was evaluated. The results showed that at higher concentrations of Pb, the percentage and rate of seed germination were decreased. Other traits such as root and shoot dry weights decreased significantly with increased lead concentrations by 70% and 23%, respectively. Total chlorophyll a + b decreased as Pb concentration was increased (66%). Proline accumulation and activity of catalase and ascorbate peroxidase enzymes increased significantly at higher concentrations of Pb by 30%, 42%, and 42%, respectively. Based on the changes in some plant traits such as enrichment coefficient, phytoextraction potential, and tolerance index, it can be concluded that B. perennis might have a high potential for phytoremediation, and also lead metal refining ability. It was observed that the Pb application did not prevent seed germination of B. perennis, but increasing concentrations disrupted some seed germination traits. Bellis perennis showed good tolerance at low concentrations of Pb, while at higher concentrations, the tolerance index decreased by about 60%, suggesting an acceptable tolerance at high concentrations. Significant accumulation of Pb in the roots of B. perennis indicated it is a suitable plant for phytoremediation in lead-contaminated environments.

A large part of the cultivated soils in western Iran is calcareous. This is effective in reducing the availability of essential nutrients in the soil and their uptake by plants. This study's aim was to investigate the effect of different levels of sulfur on chemical properties of a calcareous soil and tomato yield. The experiment was carried out in a greenhouse using sulfur at five levels of 0, 1, 2, 3, and 4 g/kg soil with the bacterium Thiobacillus thioparus with three replications (15 pots in total). Tomato seeds were sown two weeks after adding sulfur to the potting soil. At the end of the 60-day growth period, leaf samples and tomato crops were harvested to measure nutrient concentrations and determine the yield, respectively. The results showed that the application of sulfur significantly affected soil pH (19.9 to 20.4%), electrical conductivity (18.7 to 21.5%), and the availability of P (16.2 to 21.2%), Cu (16.6 to 22.8%), Zn (16.8 to 21.9%) and Fe (18.2 to 22.5%) in the soil. The concentrations of these elements were also affected in the plant tissue due to soil sulfur application in the range of 17.7 to 21.3% for P, 18.6 to 21.4% for Cu, 16.4 to 22.9% for Zn and 21.5 to 22.6% for Fe, respectively. Plant height was influenced similarly with an increase from 17.2 to 22.7%. In general, the results of this study showed that applying sulfur up to three grams per kilogram of calcareous soil could increase the uptake of nutrient elements by the plants through improving their availability which in turn resulted in the growth and yield increase of tomato.

Quick and accurate estimation of soil available water as one of the most critical soil quality indices plays an essential role in agricultural water resources management. The present study estimated the least limiting water range (LLWR) for 250 soil samples taken from Khanmirza plain in Chaharmahal and Bakhtiari province. Artificial intelligence method (combining genetic algorithm (GA) with artificial neural network (ANN)) and readily available soil properties were used for this purpose. The LLWR was considered as output variable, and sand, silt and clay percentages, organic carbon content, bulk density (BD), particle density (PD), pH, electrical conductivity (EC) and equivalent calcium carbonate (CCE) were considered as input variables. From 250 data, 200 were allocated to model training and 50 to model testing. The statistical analyses showed that the artificial neural network had a reasonable estimate of LLWR with a coefficient of determination of 0.93. Finally, the combined model of artificial neural network-genetic algorithm (ANN-GA) with the highest coefficient of determination (R2 = 0.96) was identified as the most appropriate model for predicting LLWR. The two models of artificial neural network and genetic algorithm generally showed better performance than the regression equations.