Influence of nitrogen fixing bacteria incorporate with inorganic nitrogen fertilizer on population nitrogen fixing bacteria, yield and root quality of celeriac plants (Apium graveolens L.var. Rapaceum)

Abstract

Considering the importance of cultivated a new vegetables crops in Egypt and also to what extent the use of biofertilizer can replace or reduce the application of mineral nitrogen fertilizer. A field experiment in the newly cultivated sandy soil at the National Research Centre experimental station in Nubaria region, Beheira Governorate, (30° 28' N/31° 03' E) Egypt was conducted (in the two successive winter seasons of 2007/2008 and 2008/2009) on celeriac plant cv. Monarch. A Complete randomized block design with three replicates was used in this experiment. Mixture of two free nitrogen fixing bacteria (Azotobacter chroococcum and Azospirillium lipoferum) as biofertilizer was used either individually or combined with mineral nitrogen fertilizer at the rates of 50, 75 and 100%of recommended rate. In addition to un-inoculated control (which was only given the recommended dose of mineral N). The results of analysis of variance showed that in most case, the effects of different treatments on Population Nitrogen fixing Bacteria, leaves and root yield, physical and chemical properties of roots were significant. The joint application of full dose of mineral nitrogen and biofertilizer gave the highest yield of celeriac plants represented as the fresh leaves (green yield) and root yield compared to control treatment as well as other studied treatments. In addition, the same treatment, generally decreased NO3-N in both leaves androots compared to control (full dose of mineral N).