Date

4-2010

Degree

Bachelor of Science in Biology

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Lucille C. Villegas

Co-adviser

Jocelyn T. Zarate

Abstract

Improvement in growth of lowland rice (var. NSIC-122/Angelica) and fluctuations in soil microbial population at different growth stages were studied under the influence of varying inorganic fertilizer levels, and/or using VAM fungi (Mykovam BIOTECH) and Nostoc sp. IRRI 59 treatment. Inoculation of rice seeds with Mykovam resulted to increased seedling height, greener leaf blades and longer and finer root hairs as compared to uninoculated at 10 days after seed germination. Leaf Color Chart (LCC) reading 7 days after tillering stage (45 days old), revealed 100% N deficiency for uninoculated Control and Mykovam treatments which did not receive either chemical fertilizer or Nostoc sp. IRRI 59. Chemical fertilizer addition at both 90:60:60 and 45:30:30 kg NPK ha-1 significantly promoted growth of almost all growth parameters measured. Soil sterilization, biofertilization (especially with combined Nostoc sp.+Mykovam), and chemical fertilizer at the rate of 90:60:60 kg NPK ha-1 significantly improved rice growth as indicated by increase of 83% in tiller count, 30% in height, 102% in root dry weight and 204% for shoot dry weight. VAM infection was observed through the presence of inter and intracellular fungal hyphae; however, presence of vesicles and arbuscules inside rice roots were putatively identified through microscopy. Assay for plant growth-promoting activity of different treatments revealed highly significant result in mean seedling height difference from negative control for oven-dried Nostoc sp. extracts, Mykovam only, and integrated air-dried Nostoc sp. + Mykovam extracts, with maximum value (in cm) obtained from former. Soil bacterial population was increased by inoculation with combined Mykovam and Nostoc sp. IRRI 59 under 90:60:60 kg NPK ha-1 in unsterilized soil compared to other treatments after grain-yielding stage of rice (120 days old) while inoculation with Nostoc sp. IRRI 59 alone under 0:0:0 kg NPK ha-1 increased bacterial population for sterilized soil. Actinomycete and fungal population were not determined since counts were below the detection limit of the plating technique used. Algal population in sterilized soil was higher than unsterilized soil based on mean effects of plant age. Increase in algal population was observed at tillering stage then gradually declined at grain-yielding stage. Inverse relationship was observed between algal population and levels of inorganic fertilizer.

Language

English

LC Subject

Microbiology

Document Type

Thesis

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