Date of Award

5-2002

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Science

First Advisor

D r. M. H . Soliman

Second Advisor

Dr. Abdou Abdou Soaud

Third Advisor

Pr of. Esam Husain Ganem

Abstract

The random uses of inorganic fertilizers in the UAE farms generate a serious threat about polluting the soil, and the environment. This motivates some researchers to find suitable alternatives, which can give a better crop yield, and at the same time become friendly to the environment.

The present study was performed to find environmentally friendly biological fertilizers to substitute or reduce the application of inorganic fertilizers. Actinomycetes, which are known to produce plant growth regulators (PGRs) were isolated from UAE soils. A total of fifty-seven actinomycetes were isolated from a cucumber rhizosphere soil at a farm in AI-Ain city. Out of those isolates, only three actinomycete isolates (C 21, C 33, and C 51) were selected on the basis of their ability to produce high amount of plant growth regulators (PGRs) such as auxins and gibberellins. Thin layer chromatography (TLC) analysis of culture extracts of the three isolates showed the presence of Indole acetic acid (IAA), and gibberellic acid (GA3). Bioassay of cell-free extracts from the three isolates produced significant elongation when assayed with oat coleoptiles (IAA test) and lettuce hypocotyls (GA3 test).

The three actinomycete isolates were identified to the species level using cultural, physiological, biochemical and chemotaxonomical characteristics. Isolates C 21, C 33, and C 51 were identified as Streptomyces antimycoticus, Streptomyces clavuligerus, and Streptomyces erumpens, respectively.

The three actinomycete isolates were tested in the presence and absence of organic, or inorganic fertilizers under glasshouse conditions. It was found that single treatment of fish emulsion, humic acid or seaweed extracts significantly increased the fresh and dry weights of root and shoot, root and shoot lengths, and fresh weight of fruits compared to control treatment (untreated soil).

In combined treatments, it was found that the addition of (fish emulsion combined with humic acid extract), (fish emulsion combined with seaweed extract), or (humic acid extract combined with seaweed extract) significantly increased the fresh and dry weights of root and shoot, root and shoot lengths, and fresh weight of fruits compared to the other treatments.

In the triple treatment which included fish emulsion combined with seaweed and humic acid extracts a significant increase at (P < 0.05) in the fresh and dry weights of root and shoot, root and shoot lengths, and fresh weight of fruits compared to the other treatments was reported.

The addition of the three actinomycete isolates (C 21, C 33, and C 51) to the treatments mentioned above showed significant (P < 0.05) increase in the fresh and dry weights of root and shoot, root and shoot lengths, and fresh weight of fruits compared to the control, or the treatment where the actinomycetes mixture was used alone.

In the present study, the best treatment significantly increased the plant growth and yield was the one that contained: actinomycetes, humic acid, seaweed extracts and fish emulsion.

Total microbial activity was measured at sowing and after 6 weeks of cultivation. The soil amended with fish emulsion, seaweed or humic acid extracts separately or in combination had a significantly (P < 0.05) higher total microbial activity than the non-amended Soil, or the soil amended with the inorganic fertilizer after 6 weeks of cultivation.

The nutrient contents of the roots, shoots and fruits of plants harvested after treatment with inorganic fertilizer alone, or inorganic fertilizer combined with actinomycetes mixture had a significantly (P < 0.05) higher nutrient levels than plants of other treatments. The concentrations of N, P, K, Na, Ca, Mg, Cu, Mn, Zn, Fe, B, S, CI, and NO3 in the roots, shoots and fruits were significantly (P < 0.05) higher in the treatment which included the application of the inorganic fertilizer, or inorganic fertilizer combined with actinomycetes mixture than the treatment which included the application of fish emulsion combined with seaweed and humic acid extracts, or fish emulsion combined with seaweed, humic acid extracts and actinomycetes mixture.

The inorganic fertilizer application either alone or combined with the actinomycetes mixture resulted in the highest levels of nutrients in tissues, whilst the nutrient levels of plants grown in fish emulsion combined with seaweed and humic acid extracts either alone or combined with the actinomycetes mixture were significantly less.

This is the first study to employ actinomycetes that produce PGRs with fish emulsion, humic acid and seaweed extracts as a nutrient base for plant growth. The results also indicate that these treatments can be effective for horticultural production in sandy soils such as those found in the United Arab Emirates.

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