Thumbnail Image

Theses

Browse

20171
Reset filters
Subject: Microbiology × Author: Monika ×
Reset filters

Search Results

Now showing 1 - 1 of 1
  • Thumbnail Image
    ThesisItemOpen Access
    Improvement in the symbiotic efficiency of mungbean rhizobia through application of micronutrients
    (CCSHAU, 2017) Monika; Leela Wati
    Micronutrients play an important role in increasing yield of pulses and oilseed legumes through their effects on the plant itself and on the nitrogen fixing symbiotic process. Indian soils have become deficient not only in major plant nutrients like nitrogen, phosphorous, potash but also scarce in some micronutrients like zinc, iron, molybdenum and boron. These situations suggest the need of application of micronutrients with biofertilizer under intensive cultivation of legumes as it is directly involved in biological nitrogen fixation through nitrogenase enzyme activity In the present study, a total of sixty one rhizobial isolates were retrieved from healthy mungbean root nodules using Yeast extract mannitol agar medium (YEMA). Three rhizobial isolates obtained from departmental culture collection were also included in this study. After isolation, all the rhizobial isolates were assessed for temperature tolerance (up to 450C) and salt (NaCl) tolerance (up to 5%) and characterized for plant growth promoting traits: Indole acetic acid production, phosphate solubilization, siderophore production, HCN production and ACC utilization. IAA production varied in the range of 1.19- 59.19 μg/ml and the isolate MRH59 produced maximum IAA (59.19 μg/ml) after 5 days incubation at 30 0C.The ability of rhizobial isolates to excrete ammonia, varied from 0.61 to 4.67 μg/ml. Out of sixty four rhizobial isolates, 25% rhizobial isolates showed siderophore production, 15% rhizobial isolates showed HCN production and overall 55% of rhizobial isolates showed significant ACC utilization on minimal medium plates. P-solubilization index (P-SI) varied from 0.5-2.9 after four days of incubation at 30ºC. On the basis of plant growth promoting traits, isolate MRH 59 was selected to study the effect of different concentration of micronutrients (Fe, Mo, B and Zn) on growth of mungbean rhizobia. Among various micronutrients, combination of micronutrients and different concentrations of micronutrients; 0.5% ferrous sulphate+ ammonium molybdate application in YEM broth showed maximum (11.225 log no of cfu/ml), followed by 1% ferrous sulphate (10.968 log no of cfu/ml) and 1% ammonium molybdate (10.481 log no. of cfu/ml). Ten promising rhizobial isolates namely MRH1, MRH2, MRH3, MRH4, MRH16, MRH46, MRH46, MRH48, MRH59 and MB703 which showed plant growth promoting traits were selected for plant growth evaluation of mungbean under chillum jar conditions. Among ten rhizobial isolates, mungbean plants inoculated with isolate MRH59 showed maximum nodule no, nodule weight root length, shoot length, plant dry weight, pod no, seed weight, and seed no under chillum jar conditions. Isolate MRH 59 and MB703 (as a reference strain) along with different micronutrient concentrations (1% ferrous sulphate, 1% ammonium molybdate and 0.5% ferrous sulphate+ammonium molybdate) were selected for plant growth promotion of mungbean under pot house conditions. Among various treatments, 1% ammonium molybdate application along with inoculation of rhizobial isolate MRH59 and PSB showed maximum nodule no, nodule weight, plant dry weight, seed yield, N-uptake and P-uptake. On the basis of 16S rDNA sequencing the promising isolate MRH59 was found to be much similar to Sinorhizobium sp. T25.