Response of spinach plants to biofertilization

الملخص EN

Two field trials were conducted at the Experimental Station of the Faculty of Agriculture, Fayoum, Cairo University during two successive seasons of 2001/2002 and 2002/2003 to explore the response of spinach plants to the bio-nitrogen fertilizer (namely, Azotobacter chroococcum and Azospirillium brasilense) and some different rates of mineral N fertilizer.

Mineral N fertilizer was added as ammonium nitrate (33.5% N) at the complete rate; 100% (150 kg feddan-1), its 50% (75 kg feddan-1) and 25% (37.5 kg feddan-1).

Before sowing, seeds of spinach inoculated with biofertilizer; pure (one strain) or mixed (two strains) in combination with the different rates of mineral N (100%, 50%, 25%).

The obtained results indicated that: The growth characters; plant height, No.

of leaves plant-1, leaf area leaf-1, leaves area plant-1, fresh weight plant-1 and dry weight plant-1 were significantly increased by the application of mineral N fertilizer and biofertilizers either alone or in combination as compared to control plants in both seasons.

In this respect, except No.

of leaves plant-1, the highest increase was obtained by the treatment of 100% mineral N fertilizer in combination with biofertilizer treatments and followed by the 50% mineral N fertilizer combined with bio-N fertlizer as compared to the other treatments in the two seasons.

Application of mineral N in combination with biofertilizer, gave significant increases in leaves content of photosynthetic pigments (chlorophyll a, b and total and carotenoids), total carbohydrates, proteins, nitrogen, phosphorus and potassium.

The leaves concentration of nitrite and nitrate was significantly decreased by the treatments of biofertilizer alone or in combination with mineral N fertilizer treatments in the both seasons.

No significant differences were obtained in the previous growth and chemical parameters between 100% and 50% mineral N fertilizer in combination with the mixture of biofertilizers.

Therefore, it could be recommended to use the mixture of biofertilizer (Azotobacter chroococcum and Azospirillium brasilense) in combination with 50% mineral fertilizer to obtain better growth of spinach plants and reduce the extensive use of mineral N fertilization as well as the environmental pollution with mineral N residues.