Mostafa A. Nasef, Ali M. Massoud and Medhat Y. Abou-Zeid( 2010). Bio-Inoculation And Zn Application As An Alternative Strategy Of Partial N-Mineral Needs For Alleviating The Possible Chemical Pollution Of Some Cereal CropsFayoum J. Agric. Res. &Dev.,Vol.24, No.2, July, 2010
Abstract: This work is an important strategy for understanding the local best usage of either N-mineral or N-bio-sources, whether be under demand for agricultural utilization projects. Also, it represents a huge challenge and technical solution for alleviating the possible adverse fears of human health through environmental risks as a result of excessive use of the nitrogenous chemical fertilizers for fertilizing some cereal crops as well as to support the newly technique of “clean, bio- and organic agriculture”. So, a field experiment was conducted on a clayey soil during two successive seasons of 2008-2009 and 2009-2010 at Damas village, Mit Ghamer district, El-Dakahlia Governorate, Egypt, to identify the outcome of replacing 25 % from the recommended N-mineral dose (RND) of wheat crop by using a bio-inoculation with Paenibacillus polymyxa bacteria under different rates of Zn-EDTA (i.e., 0, 1.0, 1.5 and 2.0 kg fed-1 as soil application) on wheat (Triticum aestivum L., Sakha 93 cv.) vegetative growth as well as harvest crop parameters, i.e., spike characters, weight of 1000 grain, grain and straw yields/fed & their nutrient contents of N, P, K, Fe, Mn, Zn and Cu. Soil content of available nitrogen forms (NH4+ and NO3-) as related to nitrogenase enzyme in the soil after 70 days from sowing was taken into consideration in this study. The obtained data show that grain bio-inoculation and Zn-chelate applied, as shown in the treatment (Paenibacillus polymyxa bacteria + 75 % RND + highest Zn rate of 2 kg/fed), led to an almost similar plant vegetative parameters (i.e., plant height, No. of tillers plant-1, dry weight plant-1, leaf chlorophyll a & b and carotenoids) to those received the full recommended N-mineral dose. However, the relative decrease percentages in such parameters were negotiable, insignificant and not exceeding 3 %. The reverse was true for available nitrogen forms (NH4+ and NO3-), mainly due to the pronounced increase in nitrogenase activity. The corresponding relative increase percentage in N-forms recorded 18.77 and 8.51 % over the soil treated with 100 % RND, respectively. That was true, since such increases were more closely attributed to an achieved increase (53.04 %) in the nitrogenase activity of plant rhizosphere. A similar way and a parallel trend for the growth parameters were observed with wheat spike characters (i.e., weight plant-1 and number plant-1), harvest crop parameters (i.e., grain weight plant-1, straw weight plant-1, weight of 1000 grain, grain and straw yields fed-1), grain and straw contents of N, K, Fe, Mn, Zn, and Cu. However, the obtained values of these plant parameters were achieved negotiable and insignificant differences don't exceeding 2 % at the treatment of (bio-inoculation + 75 % RND + highest Zn-chelated rate of 2 kg/fed) as compared to those treated with full recommended N-dose. So, it could be said that the integrated combination between N-bio-fixation and applied soil Zn-chelated leading to a continuous bio-fixed nitrogen slow release along the growth stages of wheat plants, to minimize its possible lose by either leaching process or volatilization, and in turn to rationalize use of N-mineral fertilizers, which is surplus point for sustainable agriculture system. Such system represents a new agriculture strategy that affects the country's economy and its development. That is due to the possible adverse fears on either crop products or human health should be alleviated, besides it represents an ideal solution to meet the excessive nitrogenous fertilizers demand.
Keywords: (Wheat, grain bio-inoculation, Zn-application, nitrogenase activity.)
