Ameliorative effect of plant growth promotion microorganisms and Nitric Oxide on morphophysiological and biochemical attributes in Pea (Pisum sativum L.) under salt stress.
| dc.contributor.advisor | Dwivedi, Prof. Padmanabh | |
| dc.contributor.author | Singh, Ajay Kumar | |
| dc.date.accessioned | 2018-06-06T06:34:14Z | |
| dc.date.available | 2018-06-06T06:34:14Z | |
| dc.date.issued | 2017 | |
| dc.description.abstract | Pea (Pisumsativum L.) is one of the most important legume vegetable crops belonging to Fabaceae family. It has many nutritional values such as high quality protein, carbohydrates, essential amino and fatty acids, fibers, vitamin A, vitamin B6, vitamin C, vitamin K, manganese, dietary fiber, phosphorus, magnesium, cooper, iron and zinc. The center of origin of Pisumsativum is Ethiopia, the Mediterranean and Central Asia with a secondary center of diversity in the Near East. Pea is adapted to many soil types, but grows best on fertile, light-textured, well-drained sandy loam soils. The soil should be rich in organic matter as it enhances better growth by supplying nutrients at a slower rate. It is very much sensitive to soil salinity and extreme acidity. The ideal soil pH range for pea production is 5.5 to 7.0.The environmental stresses resulting from climate change and unsustainable irrigation practices are predicted to have impact on crop productivity and reduce the area of available land for agriculture by 2–9% globally. Soil salinization is a serious threat to crop productivity and predicted to increase in the face of global climate change. The situation is worst in arid and semi arid regions, which are deficient in water and face high temperatures, resulting in more water loss from plants due to higher evapo-transpiration rates, aggravating the effects of salinity. Salinity stress induces a multitude of responses in plants including morphological, physiological, biochemical and molecular changes.Salts in the soil water may inhibit plant growth for two reasons. Firstly, the presence of salt in the soil solution reduces the ability of the plant to take up water and this leads to reductions in plant growth rate. This is referred to as the osmotic or water-deficit effect of salinity. Secondly, if excessive amounts of salt enter in the plant system through transpiration stream, there will be injury to cells in the transpiring leaves and this may cause further reductions in growth. Trichoderma is a genus of fungi commonly found in the soil ecosystem worldwide. The fungi grow along root surface and just below the outer most cells of roots. Trichoderma feed on soil microbes that are attracted to the root system and surrounding rhizospheres by root-excreted sugar. High microbial population near the root system encourages Trichoderma to grow within root intercellular spaces and close to the plant root surface, coordinating defences against biotic and abiotic stresses, increasing plant vigour and prove beneficial to the plant health.These fungi have been widely used as biocontrol agents and they can also stimulate plant growth and suppress plant diseases by one or more different direct and/or indirect mechanisms. The success of Trichoderma in the rhizosphere is due to their high reproductive capacity, ability to survive under very unfavourable conditions, efficiency in the utilization of nutrients, capacity to modify the rhizosphere and strong aggressiveness against plant pathogenic fungi. Responses of Trichoderma to fluctuations in environmental conditions and how plants respond to fungal metabolites are the subject of research in a number of ongoing studies. Rhizosphere is the most important and well-characterized ecological niche comprising dimensions of soil surrounding plant root zone with maximum bacterial population that are influenced by root exudates. Plant Growth Promoting Rhizobacteria (PGPR) is beneficial bacteria to the plant growth under both biotic and abiotic stress environment. PGPR have ability to colonize around the root zone and encourage plants for their growth and development through either direct or indirect mechanisms. In the direct mechanisms, which can be correlated with their capability to produce iron chelator compound siderophore, indole acetic acid (IAA), solubilise phosphorus, potassium, exo-polysaccharide and ACC deaminase activity directly help the plant in several ways: (1) Provide nutrient availability to the plant by solubilizing unavailable or fixed nutrients in the soil (2) Enhance plant growth by producing phytohormone (3) Encourage plant growth from abiotic stresses i.e. drought, salinity and water logging through reducing the production of ethylene by ACC deaminase activity and check the entry of Na+ salt into the plant cell through formation of exopolysaccharide (EPS) around the root surface. Indirectly, by releasing anti-fungal and anti- bacterial compounds i.e. hydrogen cyanide and ammonia that reduce the pathogenic microbial population. PGPR include bacteria that reside in the rhizosphere and improve plant health ultimately boosting up the plant growth. Nitric oxide (NO) is an important endogenous plant bioactive signaling molecule that has a key function in various processes of plant growth and development including seed dormancy, seed germination, primary and lateral root growth, floral transition, flowering, pollen tube growth regulation, fruit ripening, gravitropism, stomatal movements, photosynthesis, mitochondrial functionality, senescence, plant metabolism and cell death, as well as biotic and abiotic stress responses. NO plays a pivotal role in stress tolerance exerted by oxidative stress. Plants emit NO from leaves and plant mitochondria also make NO from nitrite. However, NO synthesis in plants appears more complex and major sites of NO biosynthesis in plants are protoplasts, chloroplasts, mitochondria and peroxisomes.Exogenous NO donors constitute a powerful way to supplement plants with NO. Most of the NO donors are organic compounds that form NO complexes such as sodium nitroprusside (SNP). SNP is the most widely studied compound of the iron nitrosyl family that protect plant cells from oxidative damage under stress by enhancing antioxidant enzymes. The present study was undertaken to throw light on the critical gaps existing in our knowledge of understanding the role of Plant Growth Promoting Microorganisms (PGPM) and NO in modulating the metabolism in pea in response to salinity stress. The proposed objectives of the thesis were to study: (1) Morpho-physiological and biochemical changes in pea plants under salinity stress (2) The ameliorative effect of plant growth promoting microorganisms and nitric oxide on salinity stress (3) Yield and yield attributes under salt stress and mitigating factors i.e., plant growth promoting microorganisms and nitric oxide. For the present experiment pea genotypes HUP-2 and Fungal biocontrol agent Trichodermaasperellum T42 were procured from the Department of Genetics and Plant Breeding, and the Department of Mycology and Plant Pathology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, respectively. Further, some PGPR strains were isolated from the rhizospheres of tomato, chilli and brinjal plants from different districts of Uttar Pradesh (Varanasi, Mirzapur, Sonbhadra) and Uttarakhand (Pant Nagar). All the isolated bacterial strains were evaluated for PGPR activity using following assays: (1) Phosphorus solubilization (2) Potassium solubilization (3) Siderophore production (4) Auxin production and (5) Hydrogen cyanide production. Of these PGPR, one (BP Red) showing the best PGPR activity in various assays was identified asPseudomonas aeruginosa by 16S rRNA gene sequencing usinguniversal primers: 27F (5’-AGAGTTTGATCMTGGCTCAG-3’)and 1492R (5’-TACGGYTACCTTGTTACGACTT-3’) and was used for seed treatment. The spore suspension of TrichodermaasperellumT42 and Pseudomonas aeruginosawere prepared separately with sterilized distilled water at 1×106 and 1×108 spore per ml, respectively, while 0.2% carboxy methyl cellulose (CMC) acted as a sticker. Surface sterilized seeds were taken and put into the prepared spore suspension of Trichoderma and PGPRseparately for 4 to 5 h. Then, this treated seeds were used for sowing. Twenty days after seed sowing salinity was induced by NaCl and maintained at electrical conductivity of 4, 8 and 12 dSm-1 weekly. Sodium nitroprusside (SNP- 100 µM) was used as NO donor and sprayed 21 days after seed sowing (once) as foliar application at the stress condition. Number of treatments was 19 with 3 replication used under different level of salinity stress where: T0 = Control,T1 = NaCl (4 dSm-1),T2 = NaCl (4 dSm-1) + SNP (100 µM),T3 = NaCl (4 dSm-1) + T. asperellum T42,T4 = NaCl (4 dSm-1) + P. aeruginosa,T5 = NaCl (4 dSm-1) + T. asperellum T42 + P. aeruginosa,T6 = NaCl (4 dSm-1) + SNP (100 µM) + T. asperellum T42 + P. aeruginosa,T7 = NaCl (8 dSm-1),T8 = NaCl (8 dSm-1) + SNP (100 µM),T9 = NaCl (8 dSm-1) + T. asperellum T42,T10 = NaCl (8 dSm-1) + P. aeruginosa,T11 = NaCl (8 dSm-1) + T. asperellum T42 + P. aeruginosa,T12 = NaCl (8 dSm-1) + SNP (100 µM) + T. asperellum T42 + P. aeruginosa,T13 = NaCl (12 dSm-1),T14 = NaCl (12 dSm-1) + SNP (100 µM),T15 = NaCl (12 dSm-1) + T. asperellum T42,T16 = NaCl (12 dSm-1) + P. aeruginosa,T17 = NaCl (12 dSm-1) + T. asperellum T42 + P. aeruginosa,T18= NaCl (12 dSm-1) + SNP (100 µM) + T. asperellum T42 + P. aeruginosa. Data are in the form of mean ± SEM and means followed by the same letters within the columns are not significantly different at P≤0.05 using Duncan’s multiple range test. Three plants of each treatment from each replication were selected random at the time of recording the data on various characters. Data of three plants were averaged replication-wise and mean data was used for statistical analysis. The observations were recorded at 40, 60 an 8 days after sowing (DAS). Salinity is considered a significant factor affecting crop production and agricultural sustainability. Results showed that pea plants on exposure to salt stress (4, 8 and 12 dSm-1) experienced significant reduction inmorpho-physiological and biochemical parameters such as shoot length, root length,shoot dry weight, root dry weight, biological yield, leaf area, membrane stability index, salt tolerance efficiency, chlorophyll, protein and sugar content as compared to control. These morpho-physiological and biochemical parameters were significantly increased with application of Trichodermaasperellum T42, Pseudomonas aeruginosa and sodium nitroprusside (SNP), when used singly or in combination, showed ameliorating effect at all the salinity levels as compared to control. Salinity stress induces oxidative responses on plant’s cellular structure and their metabolism, resulting in increased Electrolyte leakage,O2.-,H2O2and malondialdehyde (MDA) content, Treatments with Trichoderma, Pseudomonas and SNP, alone or in combination, reduced these concentrations, under salinity stress that resulted in stable plant membrane.Proline is also an important component which contributes to reduction of injurious effects of stress and accelerates the restoration processes. It was slightly increased under salt stress but significantly increased with application of Trichoderma, Pseudomonas and SNP, as compared to respective salinity controls (4, 8 and 12 dSm-1). Activity of two antioxidant enzymes measured i.e., superoxide dismutase and catalase and alsonitrate reductase (NR) activity, nitrite (NO2-) and Leghemoglobin content increased significantly by the application of Trichoderma, Pseudomonas and SNP as compared to respective salinity controls. Yield and yield attributes such as number of pods plant-1,average grains pod-1, grain yield plant-1, seed index, and quality parameters such as protein and sugar content present in grains significantly declined with increasing of salinity stress as compared to control. But the application of TrichodermaasperellumT42, Pseudomonas aeruginosa and SNP improved all the parameters significantly. Combined application of Trichoderma, Pseudomonas and SNP (100 µM) was more effective than the single application. In most cases the combined treatment showed the best results in various morpho-physiological and biochemical parameters under each level of salinity stress (4, 8 and 12 dSm-1) followed by Trichoderma + Pseudomonas. Single application of Trichoderma and Pseudomonas also showed better result as compared to respective salinity controls i.e. 4, 8 and 12 dSm-1 but Trichoderma performed better up to 8 dSm-1 level of salinity only, beyond this level, most of the parameters decreased as compared to other treatments. On the basis of present investigation, it is concluded that salinity stress (4, 8 and 12 dSm-1) significantly reduced the morpho-physiological, biochemical, yield and yield attributes as compared to control. These parameters were improved under salinity stress with the combined application of Trichoderma, Pseudomonas aeruginosa and SNP (nitric oxide donor) showing best response in each salinity level in comparison to respective salinity controls. Overall, treatment T6 (combination of Trichodermaasperellum T42, Pseudomonas aeruginosa and SNP) performed the best among all the ameliorative treatments by reducing salt induced stress responses in pea plants, in terms of morpho-physiological and biochemical attributes, besides yield performance. This was followed by treatment T5 (Trichodermaasperellum T42 and Pseudomonas aeruginosain combination). Therefore, it is recommended that combined use of Trichodermaasperellum T42, Pseudomonas aeruginosa and SNP can help mitigate salt stress in soil. | en_US |
| dc.identifier.citation | Pea (Pisum sativum L.) | en_US |
| dc.identifier.uri | http://krishikosh.egranth.ac.in/handle/1/5810049373 | |
| dc.keywords | Pea, Pisum sativum L., | en_US |
| dc.language.iso | en | en_US |
| dc.pages | 90p. | en_US |
| dc.publisher | Department of Plant Physiology,Institute of agricultural Science,B.H.U. Varanasi | en_US |
| dc.sub | Plant Physiology | en_US |
| dc.subject | null | en_US |
| dc.theme | Pea | en_US |
| dc.these.type | Ph.D | en_US |
| dc.title | Ameliorative effect of plant growth promotion microorganisms and Nitric Oxide on morphophysiological and biochemical attributes in Pea (Pisum sativum L.) under salt stress. | en_US |
| dc.type | Thesis | en_US |