Effect of Npk and Bioertilizer Types on Vegetative Growth, Tuber Yield and Quality of Potato

Two field experiments were carried out during the summer seasons of 2000 and 2001, at the Experimental station Farm, Faculty of Agriculture, Alexandria University, at Abies, to investigate the response of potato plants cv. Alpha, to two biofertilizer types (Nitrobein and Halex-2) under four varying percentages NPK; 25%, 50%, 75% and100% from the commercial recommended rates (180-60-96 Kg N-P-K fed -1 ). The results indicated that increasing NPK applied rate or inoculation with Halex-2 biofertilizer was accompanied with significant increases in plant height, number of branches and leaves, fresh weight and leaf area plant -1 . The mineral contents of leaves (N-PK) were positively and significantly responded as a result of increasing NPK application percent. Halex-2 appeared to be more effective than Nitrobein in this respect. Moreover, yield potential; i.e., total yield fed -1 , number of tubers plant -1 and average tuber weight were increased due to the application of 75% of the recommended NPK or biofertilizer inoculation treatments, particularly Halex-2 biofertilizer. The treatments enhanced most tuber quality characteristics (percentages of large and medium tuber sized, T.S.S. and total carbohydrates). Application of 75% of the recommended NPK level combined with Halex-2 biofertilizer appeared to be the most commercial and efficient treatment combination which gave balanced vegetative growth and higher yield potential with a best tuber quality. This particular treatment significantly produced higher yield (the increment in the total yield fed -1 was 19.8%, as average of the two seasons) than that obtained from the application of 1806096 Kg NPK fed -1 without J.Agric.&Env.Sci.Alex.Univ.,Egypt Vol.4 (2)2005 86 biofertilizer, as well as saved 25% from potato plants requirements of NPK fertilizers.