Ebtsam M. Morsy ( 2015). Efficiency of Free and Encapsulated Yeast Strains as PGRs Producers on Faba bean Plants.Middle East Journal of Applied Sciences. Volume : 05 | Issue : 02 |, Pages: 534-542.
Abstract: Twenty two yeast isolates from the rhizosphere of plants in different localities were tested to produce plant growth promoting substances and mobilized phosphate from insoluble tri-calcium phosphate. Three isolates have the ability to produce high amounts of plant growth regulators (PGRs) were selected and identified as Candida middelhoveniana 72, Rhodotorula mucilaginosa 151 and Candida blankii 375.
The encapsulation method described in this study can be effectively used to protect plant growth promoting yeast (PGPY) inoculum from adverse conditions of the soil for their successful establishment in the rhizosphere. Therefore, a field experiment was carried out at Giza Research Station, ARC, Giza, Egypt during winter season of 2013/2014 to study the effect of encapsulated growth promoting yeast species individual form or in a mixture ones compared to free cell inoculum on the growth and yield of Faba bean The obtained results recovered the highest total microbial, yeast, total asymbiotic and actinomycetes count with encapsulated and free cell of C. middelhoveniana 72 and C. blankii 375 during the two growth intervals, respectively. C. middelhoveniana 72 (encapsulated form) attained slightly more nodules number,
nodules dry weight (g) and AM-colonization (%) than free cells form, whereas the other treatments recorded less efficiency. C. blankii 375 (encapsulated form) was the superior one to obtain more nitrogenase and dehydrogenase enzyme activities than other treatments. However, mixture of encapsulated yeasts recorded the highest activity of alkaline phosphatase enzyme. The maximum percentage of macronutrients (NPK) in plants obtained with C. middelhoveniana 72 free cells form except C. blankii 375 which gave the highest K percentage only at 100 days. The highest percentage of NPK, crude protein and carbohydrates in Faba bean seeds were recorded by encapsulated form of C. middelhoveniana 72. The plant dry weight and consequently yield components were equal in value by encapsulated and free cells form of C. middelhoveniana 72 and C. blankii 375.
This study supports the trend to use yeasts as capsulated plant growth regulators for a new concept at different soils and temperatures for sustainable agriculture.
Keywords: (Plant growth regulators, yeast, encapsulation, phosphate solubilization. )
