Journal of Soil and Plant Interactions

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The effects of different levels of nitrogen (100, 200, 300 and 400 mg/L) and potassium (125, 250 and 375 mg/L) on yield and leaf N and K concentrations of tomato were investigated in perlit culture using a factorial randomized design with three replications. The highest fruit yield was obtained with 200 mg/L N. Higher levels of nitrogen decreased tomato yield. With increasing nitrogen concentration in nutrient solution, N content of leaf increased significantly whereas leaf K concentration decreased. Different potassium levels had no significant effect on tomato yield. With increasing potassium levels of nutrient solution, concentration of leaf N decreased significantly whereas concentration of leaf K increased. The greatest and the least fruit yields were obtained from N200K250 and N400K375 treatments, respectively. The highest and the lowest concentrations of leaf N were observed in N400K125 and N100K375 treatments, respectively. The greatest and the least concentrations of leaf K were observed in N100K375 and N400K125 treatments, respectively.

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One of the problems for unequal distribution of salts in the root media is toxicity of sodium (Na) and reduced uptake of some nutrients, particularly calcium (Ca) and potassium (K), by the roots growing in the saline section. There is a hypothesis that addition of Ca and K to these systems might alleviate salt-induced damages to plants. This study was carried out to evaluate the effect of Ca and K application on fruit yield, water use and crop per drop (CPD) of tomato (Lycopersicon esculentum var. Falcato F1) plants grown in a hydroponic system with unequal distribution of salts in the root media. Tomato roots were divided into two equal splits and one half was immersed in the full Johnson nutrient solution. In the other root half, 40 mM NaCl solution, alone or in combination with KCl (6 mM), CaCl2 (4 mM), K+Ca (3+2 mM) or half-strength Johnson nutrient solution, was applied. A control treatment was also used in which both root splits were immersed in the Johnson nutrient solution (C). The root splits were exchanged every 7 days. Results showed that addition of 40 mM NaCl in one side of the root media resulted in reduction of fresh and dry weight of root and shoot, stem diameter, shoot height, number of leaves and fruit yield of tomato in comparison with the control treatment. Addition of Ca, K+Ca and half-strength Johnson nutrient solution to the saline part of the root media increased significantly the root and shoot growth and fruit yield of tomato compared with the sole application of saline solution. In contrast, addition of K could not alleviate the adverse effects of salinity and even reduced the fruit yield. Application of 40 mM NaCl in one side of the root media reduced significantly the plant water use. Addition of Ca, K+Ca and half-strength Johnson nutrient solution to the saline part of the root media resulted in significant increase in CPD. Addition of Ca, K+Ca and half-strength Johnson nutrient solution caused replacement of 48, 43 and 43% of nutrient solution with saline water, respectively. According to the results of this study, in case of dynamic and non-uniform distribution of salts in the root media, by addition of Ca to the saline solution, it would be possible to replace about half of the crop water demand with saline water, with no significant fruit yield reduction.

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To study the effects of different levels of N, K and Mg on yield and growth indices of strawberry, a factorial experiment with completely randomized design and three replications was performed. Treatments included three levels of N (110, 220 and 330 mg/L), three levels of K (120, 240 and 360 mg/L) and three levels of Mg (12, 24 and 48 mg/L) that were applied to strawberry (cv. Gavita) in a hydroponic system. The yield, number of fruits, fresh and dry weight of aerial parts and roots of strawberry were measured in each treatment. Results of ANOVA showed that the effects of different levels of N were significant on yield and growth indices of strawberry. The yield decreased as the level of N increased in the growth medium, such that the highest yield was obtained in the 110 mg/L N treatment. The effects of K levels were also significant on yield and growth indices of strawberry, except for number of fruits. The yield decreased as the level of K increased. The highest yield was observed in the 120 mg/L K treatment. The Mg levels had significant effects on yield and fresh and dry weight of aerial parts of the plants. The highest strawberry yield was obtained when 24 mg/L Mg was used in the hydroponic culture. All interactive effects of N, K and Mg were significant on yield and growth indices of strawberry, and the highest yield was obtained when the levels of N, K and Mg in the hydroponic solution were 110, 120 and 24 mg/L, respectively. In general, these levels of nutrients are recommendable to obtain maximum strawberry yield in hydroponic media.

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Aloe vera is a perennial liliaceous plant with succulent green leaves joined at the stem in a whorled pattern. It is highly appreciated due to its short growth period and high economic value among all the aloe species, and is used in pharmaceuticals, cosmetic products and food products. In order to improve Aloe vera cultivation in soilless culture, an experiment was conducted in 2011 in greenhouse of College of Agriculture, University of Guilan, Rasht, Iran, as a split plot bi-factorial in completely randomized design with four replications. Four nutrient solutions containing different levels of nitrate and potassium were the main plot, which were sampled at six different periods. Results revealed that the nutrient solutions affect measured traits after 5-6 months. In other words, in research programs for this plant, it is better to record the data for at least 5-6 months. In general, the nutrient solution containing 9.8 mM nitrate and 5.8 mM potassium lead to the best results in all sampling periods. In fact, Aloe vera plants respond positively to high levels of nutrients and in solutions containing the highest level of nitrate and potassium show the highest amount of measured traits.

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Gerbera (Gerbera jamesonii L.) is one of the most important cut flowers in the world and nutrient solutions are the most important elements that increase quality and quantity of gerbera flowers. In this study, the effect of adding silicon, as an important mineral, from two sources of potassium silicate and nano silica, was investigated on physiological traits of gerbera flower, cv. Yanara. In this experiment, various concentrations of potassium silicate and nano silica were applied in different treatments including spray of nano silica in two concentrations of 12.5 and 25 mg/L (based on SiO2), drench of nano silica in two concentrations of 12.5 and 25 mg/L (based on SiO2), drench of potassium silicate in two concentrations of 25 and 50 mg/L (based on SiO2) and control (with no treatment), in three replications. The results showed that nano silica in both forms and concentrations decreased fresh weight of the flowers, but increased under-stomatal carbon dioxide. Number of flowers was increased under the 25 mg/L nano silica treatment, compared to control. Although there was no significant difference between treatments in dry weight of flowers and all photosynthetic parameters such as transpiration, photosynthesis, water use efficiency, and stomatal conductance, but in general, nano silica increased number of gerbera flowers while, potassium silicate could not improve the studied traits.

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Micaceous minerals, including phlogopite, are frequently used as the growth medium with different commercial names for greenhouse plants. The objective of this investigation was to understand the effect of phlogopite size on the release and supply of potassium (K) under greenhouse conditions. A pot experiment was carried out with a completely randomized design using factorial arrangement and 3 replications. Treatments consisted of 4 particle sizes of phlogopite and a control, as well as 2 types of nutrient solution (with/without K). Alfalfa was the test plant which was grown on a mixture of sand and phlogopite for a period of 6 months. During the growing period, shoot was harvested 4 times and the root was collected at the end of the experiment and their K concentration was measured. Under the K-free nutrient solution, the K concentration and total uptake was highest in pots containing the smallest phlogopite size. As the size of mineral decreases, the conditions for mineral weathering seem to become more favorable and therefore, mica releases its K more quickly. Therefore, if the long term K supply is important, coarse-sized phlogopite should be used. In contrast, fine-grained phlogopite is suitable when K is to be supplied very quickly.

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Sophora japonica is a deciduous tree with fragrant white flowers and panicle inflorescence. This tree has not been used widely in the landscape of central. One of the reasons is lack of enough information about asexual propagation of this plant. In the present experiment, effects of different concentrations of indole butyric acid (IBA) and indole butyric acid-potassium salt (K-IBA) (0, 5000, 10000, 15000 and 20000 mg/L) was evaluated on hardwood cuttings of Sophora  japonica with/without bottom heat. Results showed that no root formation occurred in the hardwood cuttings without bottom heat, while callus was produced. Bottom heat significantly affected all measured traits. The highest rooting percentage was obtained by 20000 mg/L IBA and K-IBA (56.66% and 53.33%, respectively), 80 days after planting the cuttings. The highest root length at 80^th day after planting was obtained with 20000 mg/L K-IBA. Rooting percentage, number of roots, leaf area, roots carbohydrate content of roots and fresh and dry weights of roots, stem and leaves increased with increasing the hormones level. However, with decreasing hormones concentration, the ratio of sprout buds to dormant buds and the amount of carbohydrates in leaves were increased.

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This pot experiment was conducted to investigate the effects of ordinary and nano forms of zinc oxide on growth and ion content of four wheat cultivars (Niknejad, Iniya, Rowshan and Moghan2) under three salinity levels (0, 75 and 150 mM NaCl). In this experiment, shoot and root dry weight, and concentration of potassium, sodium and zinc in shoots were measured. Results showed that with an increase in salinity level, the shoot and root dry weight and concentration of potassium and zinc in shoot was decreased, but shoot/root dry weight ratio, sodium concentration and sodium/potassium ratio in shoots were increased. Plants provided with nano zinc oxide had higher concentration of zinc, as compared to the ordinary form of zinc oxide. Significant reduction of sodium/potassium ratio in shoots occurred due to plant nutrition of nano zinc oxide. As a result of application of nano zinc oxide, shoot dry weight was increased in Niknejad and Iniya wheat cultivars, but it was decreased in Rowshan and Moghan2 cultivars. The results of this experiment showed that there was significant variation among wheat cultivars in response to the application of nano zinc oxide.

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Due to wasteful use of low-quality irrigation water, many agricultural lands in arid and semi-arid regions of Iran are confronted with salinity phenomenon. Salinity decreases growth and yield of plants, therefore, ways to combat deleterious effects of soil salinity on plant growth should be sought. One of these strategies is physiological prevention of salt accumulation in plants and increasing their resistance to salinity. In this greenhouse study, the main objective was to investigate the interaction effects of potassium (K) and boron (B) on yield and uptake of some micronutrients by roots and shoots of radish under salinity conditions. The experiment was carried out as factorial, based on completely randomized design with three replications, at 3 levels of K (1, 4 and 8 mM), 3 levels of B (0.1, 0.2 and 0.3 mg/L) and 3 levels of salinity (1, 4 and 8 dS/m) in quartz sand culture medium. Results showed that interaction of K and B on fresh and dry weight of shoots, fresh weight of roots and uptake of B, Fe, Cu, Zn and Mn was significant at different levels of salinity. Maximum fresh and dry weight of roots and shoots was observed in 8 mM K treatment. Also, maximum B, Fe and Mn uptake in shoots, and maximum B, Fe and Cu uptake by roots was observed at 4 mM K level. Uptake of B, Fe, Mn and Cu in roots was higher at salinity of 4 dS/m than 8 dS/m. At 4 dS/m salinity, maximum shoot yield and B uptake in roots, Zn uptake in shoots, and Mn uptake in roots and shoots, was observed at 8 mM K and 0.3 mg/L B. At salinity level of 8 dS/m, maximum B and Mn uptake in shoots and B and Fe uptake in roots was observed at 4 mM K and 0.3 mg/L B. According to the results this study, different levels of salinity and concentration of K and B, due to the interaction of these two elements, affect yield and uptake of plant micronutrients.

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Due to the beneficial effects of silicon (Si) on ornamental plants, the aim of this study was to investigate the effect of different sources and concentrations of Si on some characteristics of Rose (Rosa hybrida cv. Beverly Watson). This research was conducted in 2015 in one of the greenhouses of Parks and Landscape Organization of Urmia and in Research Laboratories of Horticultural Science Department, Faculty of Agriculture, Urmia University. A factorial experiment, based on completely randomized design, was conducted with 2 factors of Si source (calcium silicate, potassium silicate and sodium silicate) and Si concentration (0, 50, 100, 150 and 200 mg/L) with 3 replications. Treatments were applied weekly via foliar spray for 10 weeks. Results showed that Si treatment increased leaf number and thickness, leaf fresh and dry weight, leaf chlorophyll content, soluble sugar content and protein content. Because of these beneficial effects of Si on leaf number and chlorophyll content, it can improve the photosynthesis. Potassium silicate spray caused the highest content of chlorophyll a and the highest content of chlorophyll b and carotenoid was resulted from the application of calcium silicate. The highest content of fresh and dry weight of leaf, chlorophyll a, b and total chlorophyll and carotenoid was achieved in 200 mg/L silicate application. Due to the positive effects of Si on growth characteristics and photosynthetic pigments, these materials can be used to improve the rose quality.

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In order to investigate the interaction effect of salinity and supplementary calcium nitrate on growth, quantitative and qualitative attributes of flowers and mineral composition of Rosa hybrida ‘Ilona’, a factorial experiment was carried out in completely randomized design with three replications. Treatments consisted of four sodium chloride rates (0, 5, 10 and 20 mM sodium chloride) and four supplementary calcium nitrate rates (0, 1, 2, and 3 mM) and three replications, under hydroponic conditions. Results showed that sodium and chloride ions’ concentration in rose leaves was increased to toxic levels as the sodium chloride rates were increased which in turn resulted in a significant reduction in the number of flowers per plant, dry flower weight, flower stem diameter and flower vase life. Also, salinity reduced the concentration of nitrogen, calcium and potassium in the plant leaves. The use of calcium nitrate could somewhat alleviate the adverse effects of salinity. At each level of salinity, calcium nitrate consumption decreased leaf sodium and chlorine concentration and increased nitrogen and calcium content of leaves, number of flowers per plant, flower diameter and flower vase life. Significant decrease in dry weight and number of flowers per plant were respectively in the salinity range of 2.85 to 3.15 and 3.50 to 4.19 dS/m. In these salinities, the average concentration of sodium was equal to 0.34 and 0.46 while chlorine concentration was 0.36 and 1.42% respectively. With increasing salt stress, the effect of calcium nitrate on the improvement of flower vase life was decreased and more calcium nitrate was needed to supply nitrogen and calcium to the plant. Therefore, it could be concluded that under salt stress, the nitrogen and calcium requirements of the plant are higher than non-saline conditions. The results of this research showed that with increasing the salinity, supplementation of calcium nitrate can reduce the adverse effects of salinity on rose flower under hydroponic conditions

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Abstract
The reduction of water resources due to the global climate change and population growth is one of the most critical issues facing the designers and planners of the development of green spaces in cities. Against these challenges, there is an urgent need to improve the efficiency of water consumption and chain use of water resources with suitable options. In this regard, due to the significant volume of urban effluent its reuse in green space irrigation is important for water resource management from an ecological and economic point of view. Therefore, in this research, the effect of wastewater effluent from Parand city treatment plant (located in the southwest of Tehran province) on the growth traits and concentration of nitrogen, phosphorus and potassium (N, P and K) in three cover plants consisting of Frankenia (Frankenia thymifolia), Dichondra (Dichondra repens) and blue fescue (Festuca glauca), respectively, was studied. The study was conducted as a factorial experiment based on a completely randomized design with three replications. The wastewater at four levels of zero (control), 50, 75, and 100% was mixed with the fresh water and used for irrigation. After three months, some growth traits and the concentration of nutrients (N, P and K) in the plant were evaluated. The results of plant analysis showed that the N concentrations in the Frankenia and Dichondra plants were in the optimal range (2.5‒3.5%). However, the N concentrations in the shoot and root of blue fescue were less than the optimal amount. The P concentrations in all cover plants were in the optimal range (0.2‒0.4%). The K concentrations in the Frankenia and Dichondra plants were in the optimal level (1.5‒5%), but for the blue fescue plant, it was less than the optimum, indicating its deficiency. Evaluation of the growth traits showed that Frankenia plant had the best growth in irrigation with complete effluent and might be the most suitable species for irrigation with effluent.

Background and Objective: Today, treated sewage wastewater effluent is recognized as a new and permanent water resource by experts to compensate for underground water resources directly and indirectly, and treatment basically becomes meaningful when the wastewater is reused. The methods of using wastewater are extensive, including nutrition, agricultural irrigation, industries, fish farming, and green spaces. Several researches have shown that the use of effluents for irrigation have had a significant effect on some characteristics of soil and plant. Soleimani et al. (2023) evaluated the ecological risk and the accumulation of heavy metals in agricultural soils irrigated with treated sewage effluent, river water and well water along with chemical fertilizers. Their results indicated that the low concentration of heavy metals and the presence of nutrients in the treated sewage effluent make it the most suitable water resource for irrigation because it eliminates the need of farmers for chemical fertilizers and lowers the input of heavy metals to soil. In this research, the effect of municipal wastewater effluent on the growth traits and nutrients concentration of three cover plants was studied.

Methods: The study was conducted as a factorial experiment based on a completely randomized design with three replications. Wastewater effluent from Parand city treatment plant (located in the southwest of Tehran province) at four levels of zero (control), 50, 75, and 100% was mixed with the fresh water and used for irrigation of three cover plants consisting of Frankenia (Frankenia thymifolia), Dichondra (Dichondra repens) and blue fescue (Festuca glauca). After three months, some growth traits and the concentration of nitrogen, phosphorus and potassium (N, P and K) in the plant were measured by Kjeldahl, Olsen and ammonium acetate extraction (flame photometry) methods, respectively.
 
Results: The analysis of variance showed that the N, P and K concentrations in the shoot of cover plants were significantly affected by the interaction of plant type and irrigation treatment at p < 0.05. The N concentrations in the shoot of Frankenia and Dichondra plants were in the optimal range (2.5‒3.5%), but it was less than the optimum in the blue fescue indicating its deficiency. The P concentrations in the shoot of all cover plants were in the optimal range (0.2‒0.4%). The K concentrations in the shoot of Frankenia and Dichondra plants were in the optimal range (1.5‒5%), but for the blue fescue plant, it was less than the optimum, indicating K deficiency in this plant. Also, the results of the growth traits of cover plants showed that Frankenia plant had the best growth in irrigation with complete effluent and might be the most suitable species for irrigation with effluent.

Conclusions: The finding of this study showed that irrigation with complete effluent resulted in different changes of the growth traits of cover plants. The Frankenia is considered the best plant in irrigation with complete effluent, because it has performed well in all the measured growth traits. The blue fescue plant was not significantly different from the control treatment in irrigation with complete effluent, and the Dichondra plant also performed poorly in irrigation with complete effluent due to the reduction of some growth traits. Therefore, Dichondra plant is not recommended for planting in green spaces irrigated with complete effluent.

References:
1. Soleimani, H., Mansouri, B., Kiani, A., Khalid Omer, A., Tazik, M., Ebrahimzadeh, G.H., Sharafi, K., 2023. Ecological risk assessment and heavy metals accumulation in agriculture soils irrigated with treated wastewater effluent, river water, and well water combined with chemical fertilizers. Heliyon 9(3), e14580, https://doi.org/10.1016/j.heliyon.2023.e14580.

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Abstract
Melatonin has been introduced as a strong antioxidant that has a protective role in stressful conditions and acts as an osmotic regulator and metabolic modifier when different stresses occur. In order to investigate the effect of melatonin pretreatment on improving the morphophysiological traits of Calendula officinalis L., a factorial completely randomized design with three replications was conducted. Melatonin at three levels (0, 100 and 150 µM) and sodium chloride at four levels (0, 30, 60 and 90 mM) were considered as the treatments. Based on the obtained results, the highest plant height, the highest number of leaves and the longest root length were obtained in 150 μM melatonin without sodium chloride treatment. On the other hand, at 90 mM salinity and without the presence of melatonin, the lowest number of leaves and plant height were observed. The fresh weight of the root, at different levels of salinity, showed a decreasing trend with increasing salinity concentration, so that its lowest value was observed in the concentration of 90 mM salt without melatonin. The fresh weight of the root increased with the increase in melatonin concentration. The highest relative water content and potassium percentage of leaves were observed in 150 μM melatonin treatment. As the salt concentration increased, the relative water content and potassium concentration decreased. The highest amount of soluble sugar related to 60 mM salinity in combination with 100 µM melatonin and the highest amount of proline was observed in 60 mM salinity + 150 µM melatonin. The results indicated that melatonin pretreatment was effective on the vegetative and physiological traits of marigold under salinity stress and was able to reduce the effect of salinity, especially in the concentrations of 30 and 60 mM sodium chloride.

Background and Objectives: High NaCl levels, due to osmosis and ionization, can significantly diminish plant height, leaf area, and the fresh and dry weights of shoots and roots. Melatonin, a ubiquitous molecule produced in plants, acts as a growth regulator similar to indole acetic acid (IAA), which promotes cell expansion and growth. Under NaCl stress, plants close the stomata to prevent water loss, and this can result in decreased stomatal conductance and photosynthesis activity. However, it has been shown that the application of melatonin makes the stressful conditions tolerable for plants and leads to the opening of stomata, which has been reported to improve the photosynthetic machinery in sunflower and citrus plants (Brugnoli and Lauteri, 1991; Meloni et al., 2003; Ye et al., 2016). The aim of the present study was to investigate the role of melatonin in marigold, in order to improve vegetative and physiological traits.

Methods: A factorial experiment in a completely randomized design with two factors and three replications was conducted in greenhouse conditions at Sari Agricultural Sciences and Natural Resources University. Melatonin at three levels (0, 100 and 150 µM) and salinity at four levels (0, 30, 60 and 90 mM) were considered as the first and second factors, respectively. Marigold seedlings were sprayed three times every ten days. One week after the last melatonin treatment, irrigation with sodium chloride was applied every 7 days for 35 days. One week after the last application of sodium chloride, some traits such as plant height, number of leaves, flower diameter, root length, root fresh and dry weights, leaf relative water content, soluble sugar, proline, ion leakage, and sodium and potassium contents were measured.

Results: The interaction between salinity and melatonin affected the plant height, number of leaves, and root length, volume and dry weight. The highest plant height (i.e., 17 cm), the number of leaves (i.e., 34) and the root length (i.e., 18.83 cm) were obtained in the 150 μM melatonin treatment without salt. The highest root volume and dry weight were observed in 100 μM melatonin treatment without salt. The highest leaf relative water content and potassium content were obtained in 150 μM melatonin treatment. The highest amounts of soluble sugar and proline were recorded in 60 mM sodium chloride + 100 μM melatonin, and 60 mM sodium chloride + 150 μM melatonin, respectively. At 30 mM salinity without the use of melatonin, the lowest proline was recorded. The highest sodium content was recorded at 60 mM sodium chloride. At the concentration of 150 μM melatonin, the sodium content in the leaf decreased. With the increase of salt concentration, ion leakage increased and it was the highest at 90 mM salinity. At the concentration of 150 μM melatonin compared to the control, a decrease in ion leakage was observed.

Conclusions: The results showed that salinity stress reduced the vegetative traits of marigold, but the use of melatonin reduced the damage under salinity stress conditions. Melatonin, by protecting the membrane and structure of plant cells, maintaining the antioxidant system and helping to absorb potassium and reducing sodium absorption, could increase the resistance of marigold against salt stress. As a result, the use of melatonin moderated the effects of salinity and improved plant growth in saline conditions. Therefore, it is recommended to use 100 and 150 μM concentrations of melatonin for improving vegetative and physiological characteristics of marigold under salinity stress conditions.

References:
1. Brugnoli, E., Lauteri, M., 1991. Effects of salinity on stomatal conductance, photosynthetic capacity, and carbon isotope discrimination of salt-tolerant (Gossypium hirsutum L.) and salt-sensitive (Phaseolus vulgaris L.) C₃ non-halophytes. Plant Physiol. 95(2), 628–635.  https://doi.org/10.1104/pp.95.2.628.
2. Meloni, D.A., Oliva, M.A., Martinez, C.A., Cambraia, J., 2003. Photosynthesis and activity of superoxide dismutase, peroxidase and glutathione reductase in cotton under salt stress. Environ. Exp. Bot. 49(1) 69–76. https://doi.org/10.1016/S0098-8472(02)00058-8.
3. Ye, J., Wang, S., Deng, X., Yin, L., Xiong, B., Wang, X., 2016. Melatonin increased maize (Zea mays L.) seedling drought tolerance by alleviating drought-induced photosynthetic inhibition and oxidative damage. Acta Phys. Planta. 38(2), 48. https://doi.org/10.1007/s11738-015-2045-y.