Impact Of Soil Salinity Research Articles

Impact of soil salinity on the plant-growth - promoting and biological control abilities of root associated bacteria.

The effectiveness of plant growth – promoting bacteria is variable under different biotic and abiotic conditions. Abiotic factors may negatively affect the beneficial properties and efficiency of the introduced PGPR inoculants. The aim of this study was to evaluate the effect of plant growth – promoting rhizobacteria on plant growth and on the control of foot and root rot of tomatoes caused by Fusarium solani under different soil salinity conditions. Among the five tested strains, only Pseudomonas chlororaphis TSAU13, and Pseudomonas extremorientalis TSAU20 were able to stimulate plant growth and act as biological controls of foot and root rot disease of tomato. The soil salinity did not negatively affect the beneficial impacts of these strains, as they were able to colonize and survive on the roots of tomato plants under both saline and non-saline soil conditions. The improved plant height and fruit yield of tomato was also observed for plants inoculated with P. extremorientalis TSAU20. Our results indicated that, saline condition is not crucial factor in obtaining good performance with respect to the plant growth stimulating and biocontrol abilities of PGPR strains. The bacterial inoculant also enhanced antioxidant enzymes activities thereby preventing ROS induced oxidative damage in plants, and the proline concentrations in plant tissue that play an important role in plant stress tolerance.

Predicting Near‐Surface Moisture Content of Saline Soils from Near‐Infrared Reflectance Spectra with a Modified Gaussian Model

Core Ideas Moisture estimates from near‐infrared reflectance are improved with a modified Gaussian model. Artificial neural network simulations further improve moisture prediction accuracy. The proposed method yields better results than standard reflectance moisture indices. Near‐surface soil moisture is a spatially highly heterogeneous state variable that affects the hydrologic partitioning of precipitation, net ecosystem exchange, and land–atmosphere interactions. In concert with the rapid advancement of large‐scale hyperspectral remote sensing technology over the last decade, numerous methods relating reflectance to near‐surface soil moisture have been proposed. Although there is evidence that surface reflectance is conjointly controlled by moisture and salt content, little is known about the impact of soil salinity. To study the effects of soil salinity, near infrared to short‐wave infrared reflectance spectra were measured in a controlled laboratory environment for samples representing a wide range of salinity levels. A previously proposed surface moisture prediction method based on geometrical attributes of an inverted Gaussian (IG) function fitted to hyperspectral reflectance curves was revisited. Improvements were proposed by first modifying the geometrical attributes of the IG applied to predict near‐surface soil moisture and by concurrently considering multiple geometrical attributes of the IG function as input for trained artificial neural networks (ANNs). Although previously applied linear regression models that relate a single geometrical parameter to soil moisture failed to satisfactorily predict independently measured surface soil moisture, considerable improvements in prediction accuracy were achieved with both geometrical attribute modification and ANN simulations.

Impact of Soil Salinity on the Structure of the Bacterial Endophytic Community Identified from the Roots of Caliph Medic (Medicago truncatula).

In addition to being a forage crop, Caliph medic (Medicago truncatula) is also a model legume plant and is used for research focusing on the molecular characterization of the interaction between rhizobia and plants. However, the endophytic microbiome in this plant is poorly defined. Endophytic bacteria play a role in supplying plants with the basic requirements necessary for growth and development. Moreover, these bacteria also play a role in the mechanism of salinity stress adaptation in plants. As a prelude to the isolation and utilization of these bacteria in Caliph medic farming, 41 bacterial OTUs were identified in this project from within the interior of the roots of this plant by pyrosequencing of the small ribosomal subunit gene (16S rDNA) using a cultivation-independent approach. In addition, the differential abundance of these bacteria was studied following exposure of the plants to salinity stress. About 29,064 high-quality reads were obtained from the sequencing of six libraries prepared from control and salinity-treated tissues. Statistical analysis revealed that the abundance of ~70% of the OTUs was significantly (p ≤ 0.05) altered in roots that were exposed to salinity stress. Sequence analysis showed a similarity between some of the identified species and other, known, growth-promoting bacteria, marine and salt-stressed soil-borne bacteria, and nitrogen-fixing bacterial isolates. Determination of the amendments to the bacterial community due to salinity stress in Caliph medic provides a crucial step toward developing an understanding of the association of these endophytes, under salt stress conditions, in this model plant. To provide direct evidence regarding their growth promoting activity, a group of endophytic bacteria were isolated from inside of plant roots using a cultivation-dependent approach. Several of these isolates were able to produce ACC-deaminase, ammonia and IAA; and to solubilize Zn+2 and PO4-3. This data is consistent with the predicted occurrence (based on cultivation-independent techniques) of these bacteria and provides some insight into the importance of the endophytic bacteria in Caliph medic when grown under normal and saline conditions.

Impact of soil salinity on growth performance of the plant Syzygium travancoricum Gamble. in their natural habitat - A critically endangered tree species of Southern Western Ghats

Increased rate of soil salinity caused changes in macro and micro nutrients uptake, which may lead to decline in photosynthesis capacity and respiration in the plant Syzgium travancoricum Gamble. is a critically endangered species located in damp forest with marshy land, where high rate of salt accumulation has been happening. An optimum level of salinity (0.05 - 0.07) is inevitable for the proper growth and survivability of this species in their natural habitat and also for natural regeneration. A range of reduction in the number of existing plants of this species can be seen in their natural habitat due to the salinity stress.

Impact of soil salinity on arbuscular mycorrhizal fungi biodiversity and microflora biomass associated with Tamarix articulata Vahll rhizosphere in arid and semi-arid Algerian areas

Soil salinization is an increasingly important problem in many parts of the world, particularly under arid and semi-arid areas. Unfortunately, the knowledge about restoration of salt affected ecosystems using mycorrhizae is limited. The current study aims to investigate the impact of salinity on the microbial richness of the halophytic plant Tamarix articulata rhizosphere. Soil samples were collected from natural sites with increasing salinity (1.82–4.95 ds.m−1). Six arbuscular mycorrhizal fungi (AMF) species were isolated from the different saline soils and identified as Septoglomus constrictum, Funneliformis mosseae, Funneliformis geosporum, Funneliformis coronatum, Rhizophagus fasciculatus, and Gigaspora gigantea. The number of AMF spores increased with soil salinity. Total root colonization rate decreased from 65 to 16% but remained possible with soil salinity. Microbial biomass in T. articulata rhizosphere was affected by salinity. The phospholipid fatty acids (PLFA) C16:1ω5 as well as i15:0, a15:0, i16:0, i17:0, a17:0, cy17:0, C18:1ω7 and cy19:0 increased in high saline soils suggesting that AMF and bacterial biomasses increased with salinity. In contrast, ergosterol amount was negatively correlated with soil salinity indicating that ectomycorrhizal and saprotrophic fungal biomasses were reduced with salinity. Our findings highlight the adaptation of arbuscular and bacterial communities to natural soil salinity and thus the potential use of mycorrhizal T. articulata trees as an approach to restore moderately saline disturbed arid lands.

Sodium Ions Uptake by Hydroxyapatite from Bovine Bone

The negative impact of soil salinity on agricultural yields is disturbing and significant, especially when related to agricultural plants, whose sensitivity to salinity is frequently, but not exclusively, associated with the abundance of Na+ in the soil, which in excess becomes toxic for plants. This work aims to propose an alternative for the control of Na+ present in waters from saline soils, by the possibility of applying bovine hydroxyapatite as a way to remedy this problematic. Hydroxyapatite powders were processed from bovine bone. The powders were characterized by X-ray diffraction analyses. Preliminary experiments were performed in batches at room temperature, adding together 5g hydroxyapatite and a dilute solution of sodium chloride. Liquid samples were analyzed by atomic absorption spectrophotometry. The results showed that the hydroxyapatite could be a promising alternative for the reduction of Na+ concentration in waters from saline soils.

Impact of Soil Salinity on Agriculture in Arid Regions

Soil salinity is one of the most brutal environmental factors limiting the productivity of crop plants. Salinity occurs in areas that have one of three criteria; shallow groundwater, bad drainage system or poor quality of irrigation water. In salt affected soils, there are three main types of soils; Saline soils, Sodic soils and Saline-sodic soils. Salinityaffects crop growth by osmoticinfluencesand specific iron toxicities. There is a varying impact of soil salinity and irrigation water on the proportion of production for different crops. In this review, some general information is presented on how salinity affects plant growth and how different measurements of salinity in solution cultures and field studies can be reconciled to a common basis.Commonsaline soil remediation techniques to treat salinity include physical removal, leaching, and/or subsurface drainage to reduce groundwater elevations Keywords: soil, salinity, remediation, arid regions, irrigation

Impact of soil salinity on fungal vector of rhizomania virus infecting beta vulgaris

Polymyxa betae Keskin is the only natural transmitting vector of the Beet necrotic yellow vein virus (BNYVV) among the cultivated sugar beet. This work aims to study the impact of salt stress on fungus-virus-host relationships. The fungal infected fine roots of sugar beet plant naturally infected with BNYVV were collected and treated with different salt concentrations (0, 2000, 4000, 6000 and 8000 ppm) of NaCl for one day prior to mixing it with a sterile soil. After virus symptoms appeared on leaves, disease severity has been determined, leave and roots tissues were collected for BNYVV detection. It was found that severe symptoms on sugar beet inoculated with treated roots by low salt concentrations (2000 and 4000 ppm) while at high salt concentrations, 8000 ppm less injury approximately as control treated with H2O. On the other hand it was found the cystosorial colonization was increased in low salt concentrations (2000 and 4000 ppm) while decrease in high salt concentrations (6000 and 8000 ppm) especially in 8000 ppm. The same trend results were observed in virus concentration in roots where as the BNYVV concentration was increased in low salt concentrations (2000 and 4000 ppm) while decrease in high salt concentrations (6000 and 8000 ppm). So the relation between capacity of fungal vector to infect the plant by virus and salinity concentration are antagonistic. Soil salinity extremes most often lead to decrease infection of BNYVV via effect on fungal zoospore. Key words: Polymyxa betae, sugar beet, rhizomania, beet necrotic yellow vein virus (BNYVV), salinity.

Using Nonlinear Geostatistical Models in Estimating the Impact of Salinity on Crop Yield Variability

Three nonlinear geostatistical models—disjunctive kriging (DK), indicator kriging (IK), and probability kriging (PK)—were used to develop conditional probability (CP) maps based on soil salinity thresholds for two crops, alfalfa (Medicago sativa L.) and corn (Zea mays L.). The CP maps divide alfalfa and corn fields into zones with different probabilities to reach a specific yield potential (YP) at a specific soil salinity threshold. The objectives of this study were to: (i) compare the performance of the DK, IK, and PK models in developing CP maps; (ii) compare actual alfalfa and corn yield samples with the YP estimated by the three models; and (iii) provide guidance for precision management of agriculture by considering the output of the models used in this study. Yield data were collected at alfalfa and corn fields to compare the actual data with those estimated by the models. The results of this study show that the CP maps developed using the three geostatistical models are efficient in assessing the impact of soil salinity on the spatial variability of alfalfa and corn yield. The comparison of the actual yield data with the estimated CP maps from the three models showed good agreement. The IK and PK models generated very similar estimates for each of the zones; however, the zones generated by both of these models are slightly different from the zones generated using the DK model. The information from this study can be used for precision management of agricultural resources.

A Model for Quantification of Temperature Profiles via Germination Times

Current methodology to quantify temperature characteristics in germination of seeds is predominantly based on analysis of the time to reach a given germination fraction, that is, the quantiles in the distribution of the germination time of a seed. In practice interpolation between observed germination fractions at given monitoring times is used to obtain the time to reach a given germination fraction. As a consequence the obtained value will be highly dependent on the actual monitoring scheme used in the experiment. In this paper a link between currently used quantile models for the germination time and a specific type of accelerated failure time models is provided. As a consequence the observed number of germinated seeds at given monitoring times may be analysed directly by a grouped time-to-event model from which characteristics of the temperature profile may be identified and estimated. Simulations indicate that the performance of the proposed methodology is satisfactory irrespective of the actual monitoring scheme. Finally, the model is applied to a quinoa germination experiment studying the impact of soil salinity.

Does water status of Eucalyptus largiflorens (Myrtaceae) affect infection by the mistletoe Amyema miquelii (Loranthaceae)?

The impact of soil salinity and host water status on the host / parasite association between Eucalyptus largiflorens (F.Muell.) and Amyema miquelii (Lehm. ex Miq.) Tiegh. was investigated in a semi-arid floodplain environment in southern Australia. Water status of potential hosts (i.e. uninfected E. largiflorens) was assessed at a range of sites with different soil salinities and then compared with mistletoe infection at the same sites. Pre-dawn leaf water potentials (Ψ) of uninfected E. largiflorens declined with increasing salinity, while leaf δ13C values increased. The proportion of infected E. largiflorens at each site decreased significantly with increasing soil salinity. A significant relationship was found between the proportion of infected trees at each site and leaf δ13C values, but not pre-dawn Ψ, of potential hosts. The impact of mistletoes on water status of infected trees was also investigated. Among infected trees, we found no significant relationship between mistletoe volume and either pre-dawn Ψ or leaf δ13C values of hosts. However, there was a significant relationship between host midday leaf Ψ and mistletoe volume, with hosts exhibiting increased stress as mistletoe volume increased. The data suggest that increasing water and / or salinity stress make E. largiflorens a less suitable host for A. miquelii.

Vegetation changes induced by dam construction in a tropical estuary: the case of the Mánamo river, Orinoco Delta (Venezuela)

This study documents the increased distribution of mangrove communities into the oligohaline regions of the Manamo river as a consequence of a dam constructed in 1965. The dam caused a major change in the discharge regime of the water, stopping the annual floodings and allowing an extensive upriver intrusion of saline waters. Penetration of salt water from the sea due to the daily tides, that would be observed only during the dry season, occurs now throughout the year. Three sites were chosen along the upper, middle and lower river course. The evolution of site geomorphology and vegetation was evaluated over 3 periods, from 1932 to 1996, using aerial photographs and recent field surveys. Soil and plant samples were taken in the mangrove communities of two sites nearer to the river mouth along 100 m transects inland from the river fringe. The influence of sea water in soils was measured by the concentration of Na, Mg, Cl and SO4 in the interstitial soil water. In plants, the impact of soil salinity was determined by the concentration of Na, K, and Mg in mature leaves. The geomorphological processes created new habitats (sand bars) for aquatic and terrestrial vegetation. In the middle and lower river course tidal penetration of sea water due to lower river discharge salinized the soil, allowing mangrove establishment. This occurred mainly in the open sand bars or in areas with sparse herbaceous vegetation. The ion content was higher in the down river site and also higher in the subsoils compared with the topsoils. The apparent expansion rate of a plant community dominated by a mangrove species (Rhizophora mangle) increased from 1 ha yr 1 prior to the regulation of water flow, to 6‐7 ha yr 1 after the river closure. The dam influences the entire Manamo river basin, affecting the distribution of halophytic species along the river fringes.