Two field experiments were carried out during 1996/1997 and 1997/1998 seasons to study the effect of inoculation with asymbiotic N;-fixers i.e A. chrococcum or A. lipoferum. biogas manure application and inorganic N- fertilizer on the growth and yield of caraway plants.
The results of this study showed that, rhizosphere of caraway plants inoculated with asvmbiotic N;-fixers and provided with the half dose of inorganic N-fertilizcr or fertilized with biogas manure recorded higher densities of Azotobaclers, Azospirilla and inorganic phosphate dissolvers than those fertilized with the full dose of inorganic N-fertilizer.
Caraway seed inoculation with either A chrococcum or A. lipoferum in the presence of the hair dose of inorganic N-fertilizer treatments gave higher records of N-ase activitv in rhizosphere soil than those fertilized with the full dose from either inorganic N-fertilizer or biogas manure. The rhizosphere soil of carawav plants inoculated with A. chrococcum showed the highest records of ammoniacal and nitrate nitrogen whereas, available phosphorus concentration was the highest in the treatment of biogas manure application.
The highest records of growth parameters and seed yield of ( Carum carvi were obtained with Azolohacler chrococcum or Azospirillum lipoferum inoculation treatments. Planting at narrow distance produced higher seed yield /fed than the planting at wider distance. Caraway seed inoculation witi Azotobacter chrococcum and sowing at 25 * 50 cm gave the highest seed yield (kg /fed.). Also, inoculation of caraway seeds with asymbiotic N;-fixers gave higher records of N. P. K and total carbohydrates than those fertilized with either biogas manure or inorganic N-fertilizer. Whereas, biogas manure application treatment attained the highest records of oil percentage and this was observed in the two seasons.
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