1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Isolation and characterization of beneficial rhizosphere microorganisms from ragi grown in Attappady hill tract of Kerala(Department of Agricultural Microbiology, College of Agriculture, Vellayani, 2021) Gayathri, M; Chitra, NThe study entitled “Isolation and characterization of beneficial rhizosphere microorganisms from ragi grown in Attappady hill tract of Kerala” was conducted during the year 2019-2021 in the Department of Agricultural Microbiology, College of Agriculture, Vellayani, Thiruvananthapuram with the objective to isolate nitrogen fixing and phosphate solubilizing bacteria from soil and root samples collected from Attapady and select efficient isolates through in vitro screening process and assess the plant growth promotion activity by roll towel assay. Thirty six nitrogen fixing bacteria and eight phosphate solubilizing bacteria were isolated from root and soil samples from ragi grown in Attappady region. The isolates were designated as ATY1-ATY36 for NFB isolates and PSB1-PSB8 for PSB isolates. Twenty isolates were selected after eliminating isolates with similarities in colony morphological characters, in order to avoid repetition among the isolates obtained from the same sample. Both NFB and PSB isolates were characterized by morphology and biochemical tests. All selected isolates were subjected to plant growth promotion activity studies. The Indole Acetic Acid (IAA) production showed a wide range of variation from 101.22 µg mL-1 to 3.26 µg mL-1 . Gibberellic Acid (GA) production of all the twenty isolates were done and the results ranged between 10.07 µg mL-1 and 2.18 µg mL-1 . Maximum IAA and GA production was recorded in isolate ATY10. Extracellular ammonia production of the bacterial isolates ranged between 176.53±5.07 μmol mL−1 and 75.59 μmol mL−1. The nitrogen content of NFB isolates ranged between 30.75 µg mL-1 and 9 µg mL-1 . The isolate ATY33 had maximum nitrogen content. The selected PSB isolates were subjected to plate assay and broth assay using Pikovskaya’s medium. The isolate PSB1 recorded maximum zone of solubilization (18.23 mm), phosphate solubilizing index (2.82) and quantification of phosphate solubilization (53.41 mg L-1 ). The bacterial isolates were screened based on weighted average ranking. In NFB, ATY10, ATY34 and ATY35 were selected for further studies and in PSB, the isolates PSB1, PSB3 and PSB4 were selected. The selected isolates were 164 identified as Pantoea agglomerans ATY10, Rhizobium sp. ATY34, Ensifer adhaerens ATY35, Burkholderia territorii PSB1, Burkholderia cepacia PSB3 and Aeromonas hydrophila PSB4 by 16s rRNA sequencing. Effect of these isolates were assessed for plant growth promotion in vitro in ragi seeds using roll towel assay. Maximum germination percentage was recorded by Aeromonas hydrophila PSB4 (81.24 per cent) and the minimum number of days taken for germinationwas recorded by Pantoea agglomerans ATY10 treated seeds. Also, the treatment Pantoea agglomerans ATY10 recorded maximum shoot length (3.31 cm), root length (7.76 cm), seedling length (11.08 cm), seedling vigour index (876.62), root dry weight (0.443 mg) and root shoot ratio (0.50). The treatment Burkholderia territorii PSB1 recorded maximum root fresh weight (3.762 mg) and shoot dry weight (0.877 mg). The six isolates were subjected to assess the multiple traits such as phosphorus, potassium and silicate solubilizing capacity, siderophore production and antifungal activity. Burkholderia territorii PSB1 showed maximum zone of inhibition against Rhizoctonia solani (3.16 mm) and Sclerotium rolfsii (0.58 mm). The maximum antagonistic activity against Fusarium sp. and Helminthosporium sp. was recorded by Burkholderia cepacia PSB3 with 4.13 mm and 5.66 mm of zone of inhibition respectively. Burkholderia territorii PSB1 and Burkholderia cepacia PSB3 solubilized potassium alumino silicate in agar also, with clearance zone of 11.00 mm and 12.66 mm (in diameter), respectively. None of the isolates solubilized magnesium trisilicate in Bunt and Rovira medium. The siderophore production was observed in Aeromonas hydrophila PSB4 isolate in Chrome Azurol S (CAS) agar medium plates. Based on the results of the present study, it can be concluded that Pantoea agglomerans ATY10 is the superior isolate among NFB isolates for plant growth promotion. Also, the isolate Burkholderia territorii PSB1 is best among PSB isolates for plant growth promotion and biocontrol activity.Item Effect of harvesting and growth regulator on seed yield qulaity and vigour in cucumber (cucumis sativus L.)(Department of Agronomy, College of Agriculture,vellayani, 2000) Sindhu, B; Annamma GeorgeHarvest, Farmyard manure ,Gibberellic acid ,Hectare ,Ethephon AbstractA field experiment was conducted at the College of Agriculture, Vellayani to study the influence of harvest and growth regulator on seed yield, quality and vigour and also to standardise the physiological stage of maturity in cucumber. Growth characters such as length of vine, number of branches and leaf area index were significantly influenced by vegetable harvests and these characters increased with increase in number of vegetable harvests. The bearing capacity of the plant is improved by frequent picking of green fruits, but the mature fruit yield and seed yield were significantly reduced. Highest seed yield was obtained when the plants were left for seed collection without green fruit picking. Seed quality is not influenced by number of harvests. But when the economics is considered highest net return and B : C ratio were obtained for two vegetable harvest. So to obtain maximum returns we can combine seed production along with two vegetable harvests which gives some vegetable yield and reasonably good yield of quality seeds. Growth regulator caused reduction in vine length. Number of branches was not influenced by growth regulator. But LA! showed a significant Increase. Growth regulator caused significant increase in green and mature fruit yields and seed yield. Fruit yield, seed yield and net return were highest at 200 ppm of ethephon. Seed quality was not affected by the application of growth regulator except for] 000 seed weight. Seed quality is significantly influenced by stages of harvest. Weight of seeds per fruit and quality were highest for seeds when fruits were harvested 45 days after flowering which was on par with that at 30 days after flowering. Storage of fruits intact before seed extraction also had significant effect on increasing seed quality. Seed quality was highest when the seeds were extracted after storing the fruits for nine days. Even when the fruits were harvested at immature stage (15 days after flowering) the seed weight per fruit and seed quality parameters can be increased by storing the fruits intact before seed extraction for nine days. But when the fruits were harvested at 30 and 45 days after flowering there was not much variation in seed quality by post harvest storage of fruit before seed extraction.Item Breeding for gynoecy in bitter gourd (Momordica charantia L.)(Department of Vegetable Science, College of Horticulture, Vellanikkara, 2019) Minnu Ann, Jose; Pradeepkumar, TItem Physiological and molecular analysles of flowering responses in amaranthus (amaranthus spp.) and cowpea (vigna spp.) under elevated CO2 environment(Department of Plant Physiology, College of Agriculture, Vellayani, 2018) Ghade Rameshwar Pandurang; Manju, R V