Diazotroph strain-wheat cultivar affinity guarantees proper cereal yield and soil nitrogen budget

摘要

Wheat cultivar-diazotroph strain affinity was monitored in a number of laboratory and greenhouseexperiments. Four Azospirillum spp. and three Azotobacter spp. strains characterized by fixing appreciableamounts of N2 and production of IAA in culture media were tested as mono-and dual-inocula to support growthand development of three high yielding wheat cultivars. Azospirillum lipoferum (ME) isolated from maizeendorhizosphere showed the highest stimulating influence on both shoot (427 mg plant-1) and root (138 mgplant-1) biomass of cv. Giza 168. Azotobacter chroococcum (SF) taken from sorghum soil apart resulted in thehighest respective shoot and root dry weights of 389 and 116 mg plant-1 for cv. Sakha 93 as well as 368 and 96mg plant-1 for cv. Benesuief 1. Regardless of diazotroph treatment, harvested cv. Giza 168 plants contained thehighest N level (ca. 57 mg pot-1) followed by cvs. Sakha 93 and Benesuief 1 (ca. 50 mg pot-1 for either).Significant increases in soil N contents were attributed to inoculation, azospirilla overcame azotobacters in thisrespect. Nitrogen budget in the soil-wheat-diazotroph systems indicated extraordinary N gains equivalent to upto 35 kg N acre-1. The net soil N income significantly correlated with azospirilla and azotobacters loads in theplant-soil system (r= 0.999). Using 2, 3, 5- triphenyltetrazolium chloride as a vital staining agent proved thehigh colonization rate of the introduced diazotrophs particulary on root surface not inside.