Inoculation efficiency of rice plants with proper species of Azolla was
studied. In this research two species ofAzo/la namely Azol/afiliculoides and
A. pinnata were tested for growth efficiency and nitrogen fixation rate. Results
showed that Azo/la filiculoides gave greater fresh and dry yield ofbio- ·
mass compared with A. pinnata. Also, A. filiculoides gave higher percentage
of total nitrogen and Nrase activity than A. pinnata. So, A. filiculoides was
used in further study. When rice plants were inoculated with Azolla as a biofertilizer
at a rate of 100 g and 150 g/m2 combined with 30 Kg P20s/fed, the
highest densities of total bacteria and inorganic phosphate solubilizing bacteria
were obtained, respectively.
Counts of ammonifiers and nitrifiers were increased with the increasing of
Azolla inoculum rate. Ammoniacal nitrogen was the highest with Azolla application
at a rate of 150 g/m2 combined with 45 kg P20s/fed. Highest values
of plant height, fresh and dry weights of shoot system were obtained from
Azol/a inoculum rate of 150 gjm2 combined with 30 kg P20s/fed. Interaction
effect between Azolla inoculum rates and P-levels was significant on total nitrogen,
phosphorus and potassium in rice plants. Highest values of chlorophyll
a, b and carotenoids as well as total carbohydrates were obtained in the treatment
of Azolla inoculum at a rate of 150 gjm2 combined with 45 kg P20 5/fed.
The highest values of grains and straw yield and 1 000-grain weight of rice
were obtained in the treatment of Azolla inoculation at a rate of 150 gjm2
combined with 30 kg P20s/fed. in both seasons of cultivation. |
