The Interaction Effect of Biofertilization and Nitrogen Fertilization Level on Growth and Yield Attributes of Rice

THIS INVESTIGATION was carried out in the Experimental Farm, Ghazala Village, Fac. of Agric., Zagazig Univ., El-Sharkia Governorate, Egypt, during two successive seasons (2014 and 2015) to find out the effect of biofertilization with Cyanobacteria (Anabaena oryzae, Anabaena extract and the Anabaena + Anabaena extract) under four nitrogen levels (0, 25, 50 and 75 kg N/ fad·) on growth and yield of rice (Giza 178). The obtained results could be summarized as follows: biofertilization was effective to increase significantly grain, straw, and total yields/ fad particularly when Anabaena extract was tried through rice foliage at 10 and 25 days after transplanting. Mineral N fertilization failed to increase the rice grain yield/ fad and almost all yield attributes at harvest where the check N treatment recorded at par averages as those recorded due to the addition of 50 kg N/ fad where the further increase in N level was followed by significant decrease in this respect. However, plant height and physiological attributes at heading were significantly increased due to the increase of N level to 50 kg N/ fad. The bio. X mineral fertilization interaction affected grain yield/ fad and almost all yield attributes where the response equations predicted maximum grain yield/ fad of 4.26 ton due to a predicted addition of 54.1kg N/ fad. According to these results, a complementary effect could be traced between the foliar application of Anabaena and the 50 kg N/ fad level to maximize the grain, straw, and total yields/ fad. An eutrophication effect could had been taking place when Anabaena was soil added due to over growth by the algae particularly, during rice grain filling where a possible toxic effect and nutrient imbalance could have had played a role in ceiling the favourable effect of biofertilization observed up to heading particularly on plant height and greeness of leaves which was expressed in their content from chlorophyll and carotenoids.