Journal of Soil and Plant Interactions

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Soilless culture in greenhouse is being developed in Iran, as in many countries of the world. This study was conducted to evaluate the possibility of applying sawdust as well as the effect of adding bentonite and pumice on vegetative growth of bell pepper cv. Inspratian. The experiment was conducted as a completely randomized blocks design with 8 treatments and 4 replications, in greenhouse of College of Agriculture, Isfahan University of Technology. The planting media consisted of different v/v ratios [100% sawdust, sawdust+ pumice at the ratios of 5, 10 and 15%, sawdust+ bentonite at the ratios of 5, 10 and 15%, and a common planting medium (85% peat+ 15% perlite) as control]. Results showed that after peat, in most cases, plants grown in sawdust+ pumice showed better vegetative growth as compared to those of pure sawdust or sawdust+ bentonite. For example, the highest fresh and dry weight of shoots and dry weight of roots were in 85% sawdust+15% pumice treatment. The results also showed that after peat, the highest chlorophyll content was determined in 95% sawdust+ 5% pumice and 90% sawdust+ 10% bentonite media. The lowest chlorophyll content was related to 100% sawdust medium. After peat treatment, the earliest flowering, fruiting and color establishment was observed in 85% sawdust+ 15% pumice, which was not significantly different from 95% sawdust+ 5% and 90% sawdust+ 10% pumice.

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Floating culture of lettuce is developing because of the increase in water use efficiency and chemical fertilizers. In order to assess replacement time of nutrient solution and concentration of replenishment solution on growth and yield of Butterhead lettuce, a factorial experiment was conducted through completely randomized design with three replications. Each experimental unit was a 60×40×15 cm (36 L) plastic box, and four plants were grown in a spacing of 20×25 cm apart on polyester sheets. The nutrient solutions were replaced with new solutions once every 3, 4 and 5 weeks. For compensating the removed water and depleted nutrients from the solution, replenishment solutions with ⅓ and ⅔ strength were added to the tank once a week. Plants were harvested 35 days after transplanting. Results showed that there was no significant difference in fresh head weight, head periphery, number of leaves per plant, leaf dry weight, root weight, and stem length and diameter among treatments. The interaction effects between replacement time × concentration of replenishment solution was not significant for none of the growth parameters. Fresh head weight and number of leaves per plant were 265-312 g (mean 286 g) and 32-37 leaves, respectively. Chemical analysis of lettuce-head tissue indicated that concentration of macro-and-micronutrients was in optimum range in all the treatments. Head weight per plant was found significantly and positively correlated with number of leaves/plant, root weight, stem diameter and head periphery. Results of the present experiment indicated that lettuce growth and nutrients could be managed well by adding replenishment solution with ⅓ strength, without replacing the nutrients solution.

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In order to evaluate the effect of different training systems on growth, yield and fruit quality of greenhouse cucumber (Cucumis sativus cv. Gohar) this experiment was set out in a randomized complete block design with three replications. Treatments consisted of four training systems including twin-stem system (V-shape), modified twin-system, high-wire system and horizontal system (single-stem). Results showed that the highest height vine, number of nodes and leaf area were observed in high-wire and horizontal systems. But, different treatments had no significant effect on internode length. The shortest time from flowering to harvesting (14 days) was obtained in V-system. Effects of the training systems on number of fruits and marketable yield per plant in different months were evaluated. The highest number of fruits (25.73) and marketable yield (2626 gr/plant) was observed in high-wire system in April. The highest non-marketable fruit was obtained in modified-twin system. Fruits of high-wire system had the highest length (17.23 cm). Effect of different training systems on dry weight of fruits and chlorophyll content of fruit skin was not significant. Fruits harvested in V-shape system had the highest total soluble solids and potassium content. According to the results and also the importance of yield in greenhouse culture, high-wire system is recommended for low-light intensity conditions and V-shape system for high-light intensity.

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Optimum nutrition is one the most effective strategies in floriculture industry. In this regard, a factorial experiment designed based on CRD with three replications on New Guinea impatiens in greenhouse. Treatments were slow release fertilizer (12-11-18-2.7MgO-8S) at 5 levels (0, 1.5, 3, 4.5 and 6 kg/m³) and humic acid at three levels (0, 2 and 4 kg/m³), mixed with substrate. The F₁ seeds of New Guinea impatiens planted in plug trays consisting of 50% peat moss, 40% perlite and 10% rice husk (v/v) as medium. After 70 days, traits such as transplant height, number of leaves, shoot diameter, total fresh and dry weight of shoots and roots, chlorophyll content and leaf nutrient concentration was evaluated. Results showed that the highest transplant height (4.38 cm) was observed in applying 3 kg/m³ of slow-release fertilizer mixed with 4 kg/m³ of humic acid, the greatest stem diameter (3 mm) was observed in 4.5 kg/m³ of slow-release fertilizer treatment and the highest number of leaves (18.9) was observed in 3 kg/m³ of slow-release fertilizer treatment. It seems that slow-release fertilizer increased nutrient elements efficiency and decreased their leaching from the substrate and also, humic acid increased plant nutrient uptake during transplant production. According to the results of this research, it could be recommended to use 3-4.5 kg/m³ of slow- release fertilizer and 2-4 kg/m³ of humic acid in the substrate for transplant production of New Guinea impatiens.

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Abstract

In order to assess reduced nitrogen level impacts on butterhead lettuce (Lacttuca sativa L.) growth and yield, an experiment was done from May to August 2015 in research greenhouse of Shahrekord University. The experiment was conducted through randomized completed design with three replications and four treatments. The lettuce plants were grown in floating system using 60, 80, 100 and 120 mg/l nitrogen in nutrient solution. In every plot, ten plants were grown in wooden pool with 100 ×50 ×15 cm dimensions and plants were spaced 20×25 cm apart on polyester sheet. There was no significant difference among treatments in the leaf  number, head weight, root fresh weight and leaf elements nitrogen, phosphor, potassium, magnesium and zinc, but significant differences were observed among treatments in leaf  and root dry weight percent, stem length and diameter and leaf calcium, iron and manganese concentration. The largest fresh head mass were obtained from 60mg/l nitrogen (326 g/plant), but it had not significant difference with other treatments. The highest leaf and root dry weight percent, stem length and diameter was observed in 100 mg/l nitrogen concentration. Deceasing of nitrogen concentration until 60 ppm, did not reduce the weight of lettuce head.

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To investigate the effects of nutrient-solution concentrations of potassium (K) and calcium (Ca), as well as different ratios of K/Ca, on growth and flowering of lisianthus (Eustoma grandiflorum) under soilless culture conditions, a factorial experiment was conducted with two factors including two K levels (300 and 400 mg/L) and three Ca levels (80, 100 and 160 mg/L). Results showed that K= 400 mg/L increased leaf number and plant height by 10% and 5% more than K= 300 mg/L, respectively. But, did not affect shoot or root’s fresh and dry weight. The highest plant height (45.6 cm) was obtained in 100 mg/L of Ca and the highest fresh root weight was observed in 160 mg/L of Ca. The effect of K×Ca interaction was significant on the number of leaves and branches. The highest number of leaves (40.3) was observed in K=400 and Ca=160 mg/L treatment. The interaction effect of Ca×K had significant effect on traits related to flowering. The highest number of flowers (16.4), number of flowering shoots (4.7) and flower diameter (49.5 mm) were observed in K=400 and Ca=100 mg/L or K=400 and Ca=80 mg/L (K/Ca ratios of 4 and 5); while, the flower longevity was the least (10.3 days). The highest flower longevity was observed with K=300 and Ca=100 mg/L. The best nutrient solution treatment for yield and durability of flowers was K=300 and Ca= 80 mg/L (K/Ca=3.7).

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The present investigation was carried out to evaluate the impacts of different concentrations of N and Ca and N:Ca ratio in nutrient solution on growth indices, yield and tipburn of butterhead lettuce (Lactuca sativa var. Capitata) in floating system. The experiment was conducted as completely randomized design, with 8 treatments and 3 replications, in Research Greenhouse of Shahrekord University. Treatments (different concentrations of Ca and N (mg/L) in the nutrient solution) included T1 (N60 + Ca80), T2 (N80 + Ca80), T3 (N100 + Ca80), T4 (N120 + Ca80), T5 (N120 + Ca160), T6 (N160 + Ca160), T7 (N200 + Ca160) and T8 (N240 + Ca160). Results showed that there was no significant difference between treatments for number of leaves; but significant differences were observed in tipburn percent, leaf and root fresh weight, leaf and root dry weight, and stem length and diameter. The highest head weight, length and diameter of stem, and root and leaf dry weight were observed in T1 (N60 + Ca80), T2 (N80 + Ca80) and T3 (N100+ Ca80) treatments. The weight of head in different treatments varied from 218 to 326 g/plant. Increasing the N concentration to more than 100 mg/L decreased the yield. Higher yield was obtained in 80 mg/L Ca concentration as compared to 160 mg/L. The tipburn occurrence of the treatments varied from 10.5 to 42.5 percent. The lowest tipburn occurrence was observed in T2 and T6 (N:Ca=1) treatments; while it was highest in T1 and T5 (N:Ca=0.75) treatments. Leaf analysis showed that significant difference was observed among the treatments with respect to N and Ca content. The T2 treatment (N80 + Ca80) was the best due to its high yield and lower tipburn incidence

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Determining the wetting distribution pattern is essential for the proper design of drip irrigation systems. Identifying the pattern of wetting distribution enhances the efficiency of the irrigation system and water use. This study was conducted to determine the wetting distribution caused by a point source and compare it among different growth media as a factorial based on a completely randomized design with three replications. The first factor, the growth medium type, included 9 levels with a combination of zeolite, perlite and cocopeat; the second one consisted of the dripper discharge at three levels of 2, 3 and 4 liters per hour. The results showed that the effects of medium type and the interaction of the medium × dripper discharge on all measured quantities (volume of irrigation water, wetting diameter in 10 and 20 cm layers from the surface, maximum wetting area and wetting volume) were significant. The effect of the dripper discharge on all quantities except the maximum wetting area was significant too. The addition of 10% cocopeat to perlite had a positive effect on the wetting distribution pattern and increased the wetting volume by 79% at a discharge of 3 liters per hour; however, zeolite did not perform well, as compared to cocopeat, reducing the wetting volume by 30%. In general, the appropriate dripper discharge in all growth media was 3 liters per hour. The discharges of 2 and 3 liters per hour are suitable and cocopeat-perlite medium with a composition percentage of 20-80 led to forming a suitable wetting distribution pattern.

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Abstract
Climate changes and agricultural practices such as excessive use of chemical fertilizers and pesticides have intensified the effect of abiotic pressures on crop productivity and have destroyed the ecosystem. One of the strategies to moderate these pressures is the use of organic fertilizers, mycorrhizal symbiosis and microbial inoculation. In order to investigate the effect of organic fertilizer, mycorrhizal fungi and Bacillus on the growth characteristics of bell pepper, an experiment was carried out as split plots on a randomized complete block design with the main factor of organic fertilizer at two levels (with and without organic fertilizer) and the secondary factor of biofertilizer treatments at four levels [arbuscular mycorrhizal (Rhizophagus irregularis + Funeliformis mosseae), Bacillus (B. subtilis + B. amyloliquefaciens)., mycorrhizal + bacteria mixture and control without inoculation] in three replications. Soil biological properties, nutrients uptake and growth characteristics and yield of the fruit were investigated after harvest. The results showed that the organic fertilizer and mycorrhizal fungi application increased the shoot dry weight (10.3% and 17.4%, respectively) and fruit yield (11.5% and 19.9%, respectively) compared to the control. The highest microbial population (1.1 × 10⁷ CFU g^-1) and R/S ratio (110.0) were obtained in the organic fertilizer application treatment with mycorrhizal inoculation. Mycorrhizal symbiosis with organic fertilizer application improved the uptake of nitrogen (20.6%), phosphorus (46.8%), iron (35.6%) and zinc (57.2%) compared to the control, and potassium uptake was improved by Bacillus treatment as compared to the control, it increased by 22.3%. In general, the combination of organic fertilizer and mycorrhizal fungi seems to be suitable for greenhouse bell pepper cultivation.

Background and Objective: Global agriculture faces various problems such as producing food for about 8 billion people by the middle of the 21^st century. At the same time, people are struggling with economic conditions and malnutrition, as well as fierce competition for natural resources and climate change (4). Use of chemical fertilizers and pesticides has led to various environmental problems around the world. Organic farming (and the use of organic and bio-fertilizers) is a holistic development method that improves environmental sustainability, habitats, biogeochemical cycles and soil biological activity without the use of conventional fertilizers or pesticides (2). Mycorrhizal fungi have a significant environmental impact by improving soil quality such as soil biomass, structure and aggregation (1). Beneficial rhizosphere microorganisms that play a role in promoting plant growth can directly or indirectly promote plant growth. In this research, bell pepper plant was used, which is one of the most important fruit vegetables, that plantation area and its consumption are increasing (3). This research seeks to understand the relationship between mycorrhizal fungi and Bacillus bacteria with or without the use of organic fertilizers and their effect on the bell peppergrowth and nutrients uptake under greenhouse conditions.

Methods: This research was carried out as split plots on a randomized complete block design with the main factor of organic fertilizer at two levels (with and without organic fertilizer) and the secondary factor of biofertilizer treatments at four levels [arbuscular mycorrhizal (Rhizophagus irregularis + Funeliformis mosseae), Bacillus (B. amyloliquefaciens + B. subtilis), mycorrhizal + bacteria mixture and control without inoculation] in three replications. Organic fertilizer with the origin of decomposed animal manure was added in the rate of 3 kg m^-2 to the bed soil in the main plots. Arbuscular mycorrhizal inoculum was prepared from Pishtaz Varian Biotechnology Company, and was added to planting hole in 10 grams (20 spores per gram) during seedling plantation. Pepper seedlings were placed in a suspension containing Bacillus bacteria (two liters containing 10⁸ bacteria cells per liter) for 25 minutes and then planted in the greenhouse bed (1). Soil biological properties, nutrients uptake, growth characteristics and yield of the fruit were investigated after harvest.

Results: The results showed that the organic fertilizer and mycorrhizal fungi application increased the shoot dry weight (10.3% and 17.4%, respectively) and fruit yield (11.5% and 19.9%, respectively). The highest microbial population (1.1 × 10⁷ CFU g^-1) and R/S ratio (110.0) were obtained in the organic fertilizer application treatment with mycorrhizal inoculation. Plants inoculated with mycorrhizal fungi and without organic fertilizer had the highest microbial inoculation efficiency (22.73%), which showed a significant difference with the plants inoculated with Bacillus bacteria (2.23%). Mycorrhizal symbiosis with organic fertilizer application improved the uptake of nitrogen (20.6%), phosphorus (46.8%), iron (35.6%) and zinc (57.2%) compared to the control. The potassium uptake was improved by Bacillus treatment as compared to the control (i.e., it increased by 22.3%). In general, the combination of organic fertilizer and mycorrhizal fungi seems to be suitable for greenhouse bell pepper cultivation.

Conclusions: Arbuscular mycorrhizal fungi symbiosis with plant is the best biological relationship that improves the growth and productivity of plants. It plays a significant role in increasing yield and improving fruit ripening in bell pepper production. Overall, the effect of organic fertilizer and microbial inoculation with mycorrhizal fungi and Bacillus bacteria on the growth of bell pepper showed that the application of these treatments had a significant effect on the most of the measured characteristics and increased these traits except for plant height.

References:          
1. Kumari, R., Bhatnagar, S., Deepali, N, Mehla, N, Vashistha, A. 2022. Potential of organic amendments (AM fungi, PGPR, vermicompost and seaweeds) in combating salt stress- a review. Plant Stress 6: 100111. https://doi.org/10.1016/j.stress.2022.100111.
2. Lobley, M., Butler, A., Reed, M. 2009. The contribution of organic farming to rural development: an exploration of the socio-economic linkages of organic and non-organic farms in England. Land Use Policy 263: 723–735.
3. Prasad, M., Srinivasan, R., Chaudhary, M., Choudhary, M., Jat, L.K., 2019. Plant growth promoting rhizobacteria (PGPR) for sustainable agriculture: perspectives and challenges. In: Singh, A.K., Kumar, A., Singh, P.K. (Eds.), PGPR Amelioration in Sustainable Agriculture (Food Security and Environmental Management), pp. 129–157.
4. Zhang, H., Zhu, J., Gong, Z., Zhu, J.K., 2022. Abiotic stress responses in plants. Nature Reviews Genetics 23(2): 104–119.