نشریه روابط خاک و گیاه
پیاپی 49 (بهار 1401)

Salinity is one of the most important abiotic stresses that severely affect the yield and quality of plants. The use of hydrogen sulfide in low concentrations increases tolerance to various stresses, including salinity in plants. This study aimed to investigate the effect of hydrogen sulfide (H2S) on reducing the damage to almond rootstock under salinity stress. The experiment was performed as a factorial based on a completely randomized design with four replications. The treatments included four levels of salinity (0, 30, 60 and 90 mM NaCl) and four concentrations of H2S (0, 0.05, 0.10 and 0.15 mM). Results showed that salinity stress, especially at a concentration of 90 mM NaCl caused a significant decrease in stem height, relative chlorophyll and leaf relative water content and a significant increase in injury rating value, electrolyte leakage, proline and sodium concentrations of root and shoot, activities of catalase and peroxidase of leaf. However, H2S at concentrations of 0.10 and 0.15 mM improved plant growth with a decrease in electrolyte leakage and sodium concentration of root, and a significant increase in proline, relative chlorophyll and antioxidant enzyme activity ameliorated the negative effect of salinity stress and improved plant growth.

Sewage sludge has positive effects on chemical and physical properties of soil. Biochar production from sewage sludge, while having positive effects on the soil, can lead to its effective management, especially in relation to the environment. The objective of this study was to investigate the effect of sewage sludge and its biochar on water repellency and structural stability of two calcareous soils with clay loam and loam texture under corn cultivation. Sewage sludge was mixed with soils in the rates of 10, 20 and 40 t ha–1 (S1, S2 and S3). The equivalent application rates of biochar were 7.3, 14.5 and 29 t ha–1 (B1, B2 and B3). At the end of corn growing period, soil water repellency was measured by the intrinsic sorptivity method. Water-dispersible clay (WDC) was also measured as an indicator of soil structural instability. Results showed that the water repellency index (RI), ethanol sorptivity (SE) and soil-water contact angle (β) were significantly higher in sewage sludge and biochar treatments than those of control. However, the WDC in the sewage sludge and biochar treatments was significantly lower than the control. The values of RI and β in the clay loam soil were significantly higher than the loam soil. In both sewage sludge and biochar treatments, an increment in the application rate increased the RI. In the clay loam soil, the highest RI and SE were observed in the sewage sludge and then in the biochar treatment; while in the loam soil, the RI had the trend of biochar > sewage sludge > control. Overall, the results indicated that the use of organic treatments such as sewage sludge and its biochar would increase sub-critical soil water repellency and structural stability.

In order to determine the effect of different levels of nitrogen on some traits of quinoa (Giza1 genotype) under salinity stress of irrigation water, a factorial experiment was conducted in a completely randomized design with three replications in a greenhouse at Shahed University of Tehran. Nitrogen as the main factor including 0, 50, 100 and 200 kg ha-1 was applied at planting time and before flowering stage. The salinity of water including 0, 3, 6, 9, 12 and 15 dS m-1 was considered as a sub-factor in the irrigation of pots. The initial soil salinity was 13 dS m-1. Results showed that nitrogen fertilizer and water salinity had a significant effect on the measured morphological and physiological characteristics. The highest yield was obtained in the control treatment. Increasing nitrogen up to 200 kg ha-1 decreased grain yield by 8% and increased 1000-seeds weight by 13%. The highest yield (8.79 g pot-1) was obtained in the control treatment of irrigation water. Also, the salinity of irrigation water at 15 dS m-1 reduced grain yield and 1000-seeds weight by 30 and 24%, respectively. The relative water content, sodium and chloride contents of the plant increased with increasing water salinity, and plant height, potassium content and K/Na ratio of the plant decreased significantly. Increasing the salinity of irrigation water up to 15 dS m-1 caused a 6% decrease in potassium and a 9% increase in quinoa sodium. According to the obtained results, quinoa can be recommended in the areas where salinity of irrigation water and soil as well as low soil fertility are limiting factors.

Today, soil salinization and alkalization have become an environmental problem that has limited agricultural production. The use of silicon and LED light can reduce the limitation of agricultural production in saline and alkaline conditions. For this purpose, a factorial experiment based on a completely randomized design in three replications was implemented to investigate the effect of sodium silicate and light sources in reducing salinity and alkalinity stress on Physalis angulate L. Treatments included sodium silicate at 0 and 75 mg L-1, four sources of natural light greenhouse (control), red light (100%), blue light (100%) and 70% red light + 30% blue light and NaHCO3 + NaCl at 0, 10 + 40 and 20 + 80 mM. The results showed that simultaneous use of silicon and LED light in all three conditions of non-stress, mild and severe stresses increased the leaf relative water content and water use efficiency, particularly in severe stress condition. The use of silicon increased the contents of phenol and proline in both non-stress and stress conditions, and the use of LED especially blue + red light, also increased these factors. Although the interactions of the studied factors were not significant on the amount of soluble sugars, glutamine synthetase enzyme of root and shoot, Mn and Zn and SPAD index, the application of silicon as well as LED light had an increasing effect on all these factors. Therefore, the use of silicon and LED light can improve the growth factors of Physalis angulata L. and increase the resistance of this plant to salinity-alkalinity stress.

Strawberry is one of the temperate fruits, which is among the most important commercial horticultural crops. This product has found its place in the diet of millions of people due to its aroma, taste and vitamin-rich contents. Therefore, present study was conducted in the greenhouse to investigate the effect of humic acid and arginine at different levels of vermicompost on quantitative and qualitative characteristics of Gaviota strawberry. This research was carried out in a factorial experimental with complete randomized blocks design with 16 treatments, three replications and 48 plots. The first factor was substrates in 4 levels (garden soil, "garden soil + 5% vermicompost", garden soil + 10% vermicompost "and" garden soil + 20% vermicompost ") and the second factor included organic acids in 4 levels [control (water), humic acid (100 mg/l), arginine (100 mg/l) and humic acid + arginine (100 + 100 mg/l)]. The measured traits included number of leaves, fruit yield, number of fruits, fruit weight, fresh and dry weights of shoot, chlorophyll a, b and total, carotenoids, anthocyanin content, vitamin C, total soluble solids (TSS), titratable acid (TA) and TSS/TA. According to the results, "garden soil + 20% vermicompost" had a positive effect on all tested traits and increased physiological and vegetative parameters in strawberry. The highest fruit weight, chlorophyll a, b and total, carotenoids, anthocyanin content, and vitamin C were obtained in the treatment of "humic acid + arginine". Interaction effect of "planting medium × organic acid" showed that the highest number of leaves, highest yield and number of fruits were related to "garden soil + 20% vermicompost × humic acid + arginine" treatment.

Sorghum is of the most important forage plants with high production potential, the ability to grow in areas with poor soil, and high adaptation to stresses. To assess the effect of water deficit stress, the production potential and the relationship between important traits, 36 forage sorghum cultivars were studied under water deficit condition using a 6×6 Lattice design at the research farm of Shahid Bahonar University of Kerman in May, 2020. Water deficit was applied at the beginning of heading stage by irrigating at 85% depletion of soil available water. The non-stress conditions consisted of irrigation when 50% of the total available water was depleted from the root zone. The ANOVA showed that water deficit significantly reduced fresh forage yield and plant height by 44.80 and 18.28%, respectively. Cultivars unl Hybrid3, Wray, Speed Feed, and Smith had the highest fresh forage yields in both moisture conditions. Mean comparisons of MP, YI, GMP, and STI indices and principal component analysis for different indices showed that unl Hybrid3, Speed Feed, Wray, Smith, ICSV 25264, and Dale were as tolerant and high yielding cultivars in both moisture conditions. Based on the results of path analysis, plant height and stem diameter had the most direct effect on fresh forage yield under non-stress and water stress conditions, respectively. They had the most indirect effect on sorghum fresh forage yield through stem diameter and plant height, respectively. It may be concluded that water stress at the reproductive growth stage significantly reduced the growth and forage yield of sorghum. However, sufficient variation in the studied germplasm suggested the possibility of selection for more tolerant cultivars. The more tolerant cultivars with high yield potential in the studied germplasm may be proposed for cultivation in regions with limited water resources and traits identified effective on yield increase are suggested for breeding objectives.