Response of mint to some organic agriculture practices under greenhouse conditions

A green house experiment was laid out at Giza Research Station, Agricultural Research 
Center (ARC), in clay loam soil, during summer season 2012. The effect of application of some 
plant growth promoting rhizobacteria (PGPR) on growth, yield and components of mint plant 
spearmint (Mentha viridis Linne) in combination with using organic fertilizers, i.e., compost at a 
rate of 15 ton/fed-1 was studied. Also, the application of recommended NPK mineral fertilizers with 
a rate of 500 Kg Ammonium sulphate, 150 Kg P2 O5 and 225 Kg K2O /fed-1 was evaluated. The 
PGPR used were 1) N2 fixing bacteria e.g. Azotobacter chroococcum, Azospirillum brasilense and 
Cyanobacteria, e.g., Anabaena, Nostoc and Spirulina, 2) Phosphate dissolving bacteria (PDB), 
e.g., Bacillus megaterium and 3) Potassium release bacteria (PRB), e.g., Bacillus circulans. The 
results indicated that application of various PGPR did support both vegetative growth and yield of 
mint plants. Also, B. megaterium, B. circulans and Azospirillum brasilense had a significant 
influence as compared to other PGPR applied. Moreover, mixed PGPR scored higher values for all 
tested parameters as compared to applied compost as such. Application of B. circulans resulted in 
higher percentage (1.52%) of total oil yield more than the application of each B. megaterium 
0.98%, Azotobacter chroococcum (1.00%), Cyanobacteria (1.04%) and compost (1.08%).