Future soil moisture and temperature extremes imply expanding suitability for rainfed agriculture in temperate drylands.
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ABSTRACT:
SUBMITTER: Bradford JB
PROVIDER: S-EPMC5635027 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Moisture stress in rainfed areas has significant adverse impacts on plant growth and yield. Plant growth promoting rhizobacteria (PGPR) plays an important role in the revegetation and rehabilitation of rainfed areas by modulating plant growth and metabolism and improving the fertility status of the rhizosphere soils. The current study explored the positive role of PGPR and salicylic acid (SA) on the health of the rhizosphere soil and plants grown under rainfed conditions. Maize seeds of two different varieties, i.e., SWL-2002 (drought tolerant) and CZP-2001 (drought sensitive), were soaked for 4 h prior to sowing in 24-h old culture of Planomicrobium chinense strain P1 (accession no. MF616408) and Bacillus cereus strain P2 (accession no. MF616406). The foliar spray of SA (150 mg/L) was applied on 28-days old seedlings. The combined treatment of the consortium of PGPR and SA not only alleviated the adverse effects of low moisture stress of soil in rainfed area but also resulted in significant accumulation of leaf chlorophyll content (40% and 24%), chlorophyll fluorescence (52% and 34%) and carotenoids (57% and 36%) in the shoot of both the varieties. The PGPR inoculation significantly reduced lipid peroxidation (33% and 23%) and decreased the proline content and antioxidant enzymes activities (32% and 38%) as compared to plants grown in rainfed soil. Significant increases (>52%) were noted in the contents of Ca, Mg, K Cu, Co, Fe and Zn in the shoots of plants and rhizosphere of maize inoculated with the PGPR consortium. The soil organic matter, total nitrogen and C/N ratio were increased (42%), concomitant with the decrease in the bulk density of the rhizosphere. The PGPR consortium, SA and their combined treatment significantly enhanced the IAA (73%) and GA (70%) contents but decreased (55%) the ABA content of shoot. The rhizosphere of plants treated with PGPR, SA and consortium showed a maximum accumulation (>50%) of IAA, GA and ABA contents, the sensitive variety had much higher ABA content than the tolerant variety. It is inferred from the results that rhizosphere soil of treated plants enriched with nutrients content, organic matter and greater concentration of growth promoting phytohormones, as well as stress hormone ABA, which has better potential for seed germination and establishment of seedlings for succeeding crops.
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Project description:Increasing population has posed insurmountable challenges to agriculture in the provision of future food security, particularly in the Middle East and North Africa (MENA) region where biophysical conditions are not well-suited for agriculture. Iran, as a major agricultural country in the MENA region, has long been in the quest for food self-sufficiency, however, the capability of its land and water resources to realize this goal is largely unknown. Using very high-resolution spatial data sets, we evaluated the capacity of Iran's land for sustainable crop production based on the soil properties, topography, and climate conditions. We classified Iran's land suitability for cropping as (million ha): very good 0.4% (0.6), good 2.2% (3.6), medium 7.9% (12.8), poor 11.4% (18.5), very poor 6.3% (10.2), unsuitable 60.0% (97.4), and excluded areas 11.9% (19.3). In addition to overarching limitations caused by low precipitation, low soil organic carbon, steep slope, and high soil sodium content were the predominant soil and terrain factors limiting the agricultural land suitability in Iran. About 50% of the Iran's existing croplands are located in low-quality lands, representing an unsustainable practice. There is little room for cropland expansion to increase production but redistribution of cropland to more suitable areas may improve sustainability and reduce pressure on water resources, land, and ecosystem in Iran.
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Project description:Demand for agricultural crop continues to escalate in response to increasing population and damage of prime cropland for cultivation. Research interest is diverted to utilize soils with marginal plant production. Moisture stress has negative impact on crop growth and productivity. The plant growth promoting rhizobacteria (PGPR) and plant growth regulators (PGR) are vital for plant developmental process under moisture stress. The current study was carried out to investigate the effect of PGPR and PGRs (Salicylic acid and Putrescine) on the physiological activities of chickpea grown in sandy soil. The bacterial isolates were characterized based on biochemical characters including Gram-staining, P-solubilisation, antibacterial and antifungal activities and catalases and oxidases activities and were also screened for the production of indole-3-acetic acid (IAA), hydrogen cyanide (HCN) and ammonia (NH3). The bacterial strains were identified as Bacillus subtilis, Bacillus thuringiensis and Bacillus megaterium based on the results of 16S-rRNA gene sequencing. Chickpea seeds of two varieties (Punjab Noor-2009 and 93127) differing in sensitivity to drought were soaked for 3 h before sowing in fresh grown cultures of isolates. Both the PGRs were applied (150 mg/L), as foliar spray on 20 days old seedlings of chickpea. Moisture stress significantly reduced the physiological parameters but the inoculation of PGPR and PGR treatment effectively ameliorated the adverse effects of moisture stress. The result showed that chickpea plants treated with PGPR and PGR significantly enhanced the chlorophyll, protein and sugar contents. Shoot and root fresh (81%) and dry weights (77%) were also enhanced significantly in the treated plants. Leaf proline content, lipid peroxidation and antioxidant enzymes (CAT, APOX, POD and SOD) were increased in reaction to drought stress but decreased due to PGPR. The plant height (61%), grain weight (41%), number of nodules (78%) and pod (88%), plant yield (76%), pod weight (53%) and total biomass (54%) were higher in PGPR and PGR treated chickpea plants grown in sandy soil. It is concluded from the present study that the integrative use of PGPR and PGRs is a promising method and eco-friendly strategy for increasing drought tolerance in crop plants.
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