'Ur (Town)' in the classical theory of Thinai: Based on Aingurunooru

The land is the basis for the survival of life. Therefore, the ancient Tamil poets and the ancient Tamil grammarians gave more importance to the land in the functions of creation and grammar. It is worth noting here that in the three-subjects distinction between the ecological and moral symbolism of human life (the triad of the first, thematic, and the object), the land and time are the primary objects. The strategies adopted by classical Tamil poets to place internal and external emotions as poems are essentially very important and should be identified separately. In particular, the poets who have written the Agam songs have inculcated in their minds the idea of Thinai theory (land, time, natural resources, etc.). One of the classical books in Tamil is Aingurunooru. The poets who have composed the chapters in this book, which have been planned and recited in five categories, have also composed poems with the names of the towns. The poets have composed the poems with a good understanding of the Thinai. Poets have given a significant place to the land (the habitat) in the singing of nature. This character can be seen in Aingurunooru. We can also take this as a general theoretical concept for the Sangam Classical texts on the place name post, like Orupanai chothukku is oru choru padham (for the entire pot, it is enough to test the single grain for the desired level of cooking)

A Paripaadal Perspective on the Unique Identification of Pandiya Nadu Poets

Paripadal is one of the texts of Sangam literature. Among the 13 poets who sang paripadal, the people of Pandiya Nadu have been singled out in this article. Everyone knows that Paripaadal is a Pandiya Nadu. In addition to Madurai, Vaiyai, Tiruparangunram, and Azagarkoil are found as hymns in this book. Its songs are sung on the topics of Vaiyai, Sevvel, and Thirumal. It is not possible to conclude that all the poets who sang were poets of Pandiya Nadu, as the scene of the song was in the Pandiya Nadu areas around Madurai. Some of the poets have sung the praises of the Pandiya region or the Pandiya king in allegorical and laudatory terms in the context of praising the Pandiya region or the Pandiya king in their songs. However, this structure is not found in the songs of some poets. They sing only what they have come to sing. In the songs sung by poets, knowingly or unknowingly, they write about their land, country, and king in a state of admiration and through metaphors. On the basis of this, it is possible to identify the teachers Nallanthuvanar, Ilamperuvazhuthiyar, Karumpillaipoothanar, Keeranthaiyar, Kundramboothanar, Nappannar, Nalvazhuthiyar, Nallazhisiyar, and Mayodakovanar as Pandiya Nadu poets. However, this is not the case in the verses of some of the poets, and the four poets, Kaduvan Ilaveinanar, Kesavanar, Nallasthanar, and Nallazhuniyar could not be distinguished as Pandiya folk

Enhancing phytoremediation of chromium-stressed soils through plant-growth-promoting bacteria

Chromium, specifically hexavalent chromium is one of the most toxic pollutants that are released into soils by various anthropogenic activities. It has numerous adverse effects not only on plant system but also on beneficial soil microorganisms which are the indicators of soil fertility and health. Recent emergence of phytoremediation as an environmental friendly and economical approach to decontaminate the chromium stressed soils has received wider attention. But major drawback of this process is that it takes long time. Application of multifunctional plant-growth-promoting bacteria (PGPB) exhibiting chromium resistance and reducing traits when used as bioinoculants with phytoremediating plants, has resulted in a better plant growth and chromium remediating efficiency in a short time span. PGPB improve chromium uptake by modifying root architecture, secreting metal sequestering molecules in rhizosphere and alleviating chromium induced phytotoxicity. The purpose of this review is to highlight the plant-beneficial traits of PGPB to accelerate plant-growth and concurrently ameliorate phytoremediation of chromium contaminated soils

Mechanisms and applications of plant growth promoting rhizobacteria: Current perspective

Plant growth promoting rhizobacteria are the soil bacteria inhabiting around/on the root surface and are directly or indirectly involved in promoting plant growth and development via production and secretion of various regulatory chemicals in the vicinity of rhizosphere. Generally, plant growth promoting rhizobacteria facilitate the plant growth directly by either assisting in resource acquisition (nitrogen, phosphorus and essential minerals) or modulating plant hormone levels, or indirectly by decreasing the inhibitory effects of various pathogens on plant growth and development in the forms of biocontrol agents. Various studies have documented the increased health and productivity of different plant species by the application of plant growth promoting rhizobacteria under both normal and stressed conditions. The plant-beneficial rhizobacteria may decrease the global dependence on hazardous agricultural chemicals which destabilize the agro-ecosystems. This review accentuates the perception of the rhizosphere and plant growth promoting rhizobacteria under the current perspectives. Further, explicit outlooks on the different mechanisms of rhizobacteria mediated plant growth promotion have been described in detail with the recent development and research. Finally, the latest paradigms of applicability of these beneficial rhizobacteria in different agro-ecosystems have been presented comprehensively under both normal and stress conditions to highlight the recent trends with the aim to develop future insights

Effects of pesticides on plant growth promoting traits of Mesorhizobium strain MRC4

The objective of this study was to assess the effect of selected pesticides [herbicides (metribuzin and glyphosate), insecticides (imidacloprid and thiamethoxam) and fungicides (hexaconazole, metalaxyl and kitazin)] at recommended and higher dose rates on plant growth promoting activities of the Mesorhizobium sp. isolated from chickpea-nodules. A total of 50 rhizobial strains recovered from the nodules of chickpea root systems were identified following morphological, biochemical and host-specificity tests and tested for pesticide-tolerance. Among these strains, the Mesorhizobium sp. strain MRC4 was specifically selected due to the highest tolerance levels for all selected pesticides and the maximum production of plant growth promoting substances. Strain MRC4 produced indole acetic acid (44 μg ml−1), siderophores [salicylic acid (35 μg ml−1) and 2,3-dihydroxy benzoic acid (19 μg ml−1)], exo-polysaccharides (21 μg ml−1), HCN and ammonia. Under pesticide-stress, pesticide-concentration dependent progressive-decline in all plant growth promoting traits of the Mesorhizobium sp. strain MRC4 exposed was observed except for exo-polysaccharides which consistently increased with exceeding the concentration of each pesticide from recommended dose. For instance, hexaconazole at three times the recommended dose elicited the maximum stress on siderophore-biosynthesis by the Mesorhizobium sp. strain MRC4 and decreased salicylic acid and DHBA by 40% and 47%, respectively and the greatest stimulatory effect on exo-polysaccharides secretion was shown by imidacloprid which stimulated the Mesorhizobium sp. strain MRC4 to secrete EPS by 38%, compared to control. Generally, the maximum toxicity to plant growth promoting traits of Mesorhizobium was shown by glyphosate, thiamethoxam and hexaconazole, at three times the recommended rate among herbicides, insecticides and fungicides, respectively. This study revealed an additional aspect of the toxicological mechanisms of the pesticides through which they suppress the plant growth

Toxicological assessment of selective pesticides towards plant growth promoting activities of phosphate solubilizing Pseudomonas aeruginosa

The study was designed to assess the effect of selected pesticides (metribuzin, glyphosate, imidacloprid, thiamethoxam, hexaconazole, metalaxyl and kitazin) at the recommended and higher rates on plant growth promoting activities of Pseudomonas aeruginosa strain PS1 isolated from mustard (Brassica compestris) rhizosphere. The strain PS1 was specifically chosen owing to its substantial tolerance against pesticides, phosphate solubilization and considerable production of indole acetic acid, siderophores, exo-polysaccharides, HCN and ammonia. Plant growth promoting traits of the strain PS1 decreased consistently as the concentrations of each pesticide was increased from the recommended dose to the higher ones. Generally, the maximum toxicity to plant growth promoting traits was displayed by pesticides at three times the recommended field rate. However, the effect on the plant growth promoting activities of the P. aeruginosa strain PS1 at the recommended dose of each pesticide was less hazardous. This study revealed an additional aspect of the toxicological mechanisms of the pesticides through which they suppress the plant growth