Document Type : Original Article
Authors
1
Researcher, Soil and Water Department, Khorasan Razavi Agricultural and Natural Resources Research and Education Center, AREEO, Mashhad, Iran
2
Instructor, Horticulture Crops Research Department, Khorasan Razavi Agricultural and Natural Resources Research and Education Center, AREEO, Mashhad, Iran.
3
3Instructor, Horticulture Crops Research Department, Khorasan Razavi Agricultural and Natural Resources Research and Education Center, AREEO, Mashhad, Iran.
4
Research instructor, Iranian Pistachio Research Institute, Khorasan Razavi Agricultural and Natural Resources Research and Education Center, AREEO, Rafsanjan, Iran
5
M.Sc., Department of Horticulture Crops, Khorasan Razavi Agricultural and Natural Resources Research and Education Center, AREEO, Mashhad, Iran
Abstract
Introduction: Soil salinity and alkalinity are some of the biggest factors limiting the production of agricultural products worldwide. Pistachio (Pistacia vera L.) is the most commonly cultivated fruit tree in Iran due to its relatively high salt tolerance, low water requirements, and high economic value (Sherafati et al., 2022). Several factors have caused a decrease in the yield of pistachio orchards in the country, including the selection of incompatible cultivars, soil and water salinity, climatic stress, and imbalanced nutrition (Sherafati et al., 2016). Recent studies indicate that microorganisms can make plants more resistant to salinity and alkalinity stress (Khavazi et al., 2013).
Material and methods: The present study was conducted to investigate the effect of haloalkaliphile bacterial strains native to the Razavi Khorasan region (which had the highest ability to produce plant growth promoting, including production of ammonia, tri-indole acetic acid, and ACC deaminase) on the vegetative growth of pistachio seedlings and some nutrients concentration (phosphorous, potassium, calcium, sodium, chlorine, zinc and boron) in the factorial split-plot arrangement based on a randomized complete design (RCD) and under garden conditions in 2021-2022. Three levels of saline irrigation (8, 12 and 16 ds m-1), two pistachio cultivars, Daneshmandi and Akbari, and the use of two superior and selected strains of native haloalkaliphilic bacteria, Virgibacillus marismortui, and Alkalibacillus haloalkaliphilus at four levels (each one alone, mixing both strains and control) were studied in three replicates consisting of two seedlings in each replicate. The studied traits in the project included stem length and diameter, number of leaves, leaf area, and chlorophyll index in the seedlings, and phosphorous, potassium, calcium, sodium, chlorine, zinc, and boron concentrations which were recorded and analyzed.
Results and discussion: The results of the analysis of variance showed that almost all traits were significant at the 0.01 level under the influence of salinity, variety, and bacterial strain. The effect of cultivar type on measured vegetative traits and bacteria type on element concentration was more significant than the effect of other experimental factors. Akbari cultivar showed superiority in all traits and calcium concentrations except for the chlorophyll index. The trend of chlorophyll index was inverse of the leaf area; and increased with increasing salinity. Virgibacillus marismortui bacteria strain increased vegetative traits including stem length and diameter and leaf area, calcium concentration by 6, 5, 0.17, and 0.2 %, respectively, compared to the control. However, the application of Alkalibacillus haloalkaliphilus bacteria treatment decreased the concentration of sodium and chlorine ions by 18.5% and 12.8%, respectively, compared to the control.The application of the mixed stains treatment of Virgibacillus marismortui, and Alkalibacillus haloalkaliphilus caused an increase in the chlorophyll index (0.6%), the least decrease in the number of fallen leaves (5.7%) and microelements increasing concentration of zinc (2.1%) and boron (1.5%) compared to the control. The highest concentration of calcium and the lowest concentration of sodium were obtained under the influence of Virgibacillus marismortui bacteria, and the lowest concentration of chlorine and the highest concentration of phosphorus, potassium, zinc, and boron were obtained under the influence of inoculation with Alkalibacillus haloalkaliphilus bacteria.
Conclusion: In general, Virgibacillus marismortui strain in salinities of 12 to 16 dS m-1 in the Akbari cultivar is known as the best treatment for increasing the growth characteristics of pistachio seedlings. However, the highest chlorophyll index, and concentration of phosphorus, potassium, zinc, and boron elements were obtained under the influence of Alkalibacillus haloalkaliphilus strain at the highest salinity level (16 dS m-1) for the Akbari cultivar. In general, the use of extremophilic bacteria in high salinities is recommended, and due to the different chemistry of the investigated elements and the different growth characteristics of these two bacteria, the use of Virgibacillus marismortui bacteria in sodium salt conditions is recommended.
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