Bio-Organic Farming of Grain Sorghum and its Effect on Growth, Physiological and Yield Parameters and Antioxidant Enzymes Activity

Two field experiments were conducted in the new land of Youssef El-Sedeek, Fayoum Governorate, Egypt during the two successive seasons of 2007 and 2008 to investigate the influence of certain bio-organic farming treatments on growth parameters, yield, chemical constituents and some enzyme activities of sorghum varieties i.e, Dorado and Giza 15. The obtained results indicated that sorghum cultivars Dorado and Giza 15 were significantly different for the studied growth parameters at 40, 70 and 100 days old and yield and its components except the specific leaf area that was insignificant. Dorado c.v. surpassed Giza 15 cv. in dry weight/plant, LA, LAI, LAR, SLW, weight of panicle, grainspanicle, shelling %, seed index, straw yield/plant, biological yield/plant, grain yield (ton/fed)., straw yield (ton/fed)., biological yield (ton/fed). and harvest index. There were significant differences of growth characters and yield and its components except specific leaf area and harvest index obtained when plant were applied by bio-fertilizer. the combined inoculation with Azotobacter vinelandlii and Pseudomonas fluorescens surpassed the single inoculation either in presence of full or double full dose of organic manure in all characters but the positive control of the recommended doses of NPK recorded the highest significant values in all growth characters at all tested plant ages and yield and its components, while the combined inoculation treatment in presence of either full or double full organic matter dose came in the second order. The effect of interaction between sorghum cultivars and bio-fertilizer showed a significant effect on all parameters under study except specific leaf weight, it is obvious from the results that Dorado cultivar fertilized with bio-fertilizer gave the highest results at most characters under study. In comparison with the positive control, comparable results, without significant differences, were obtained due to the application of diverse bio-organic treatments for phosphorus and potassium grain content. For nitrogen and protein grain content, the positive control recorded the highest values. As to the enzymes activities of peroxidase, and catalase, application of the double full dose of organic manure and the combined inoculum of Azotobacter and Pseudomonas increased both peroxidase and catalase irrespective of the tested sorghum varieties. Giza 15 sorghum variety showed high enzyme activities when compared to Dorado variety. The positive control recorded the lowest values of the activities of the tested enzymes.