EFFECT OF FOLIAR SPRAY WITH SOME MICRONUTRIENTS AND SLOW RELEASE NITROGEN FERTILIZERS RATES ON PRODUCTIVITY AND QUALITY OF SWEET POTATO (Ipomea batats L.).

The present investigation was carried out at El- Bramoon Experimental Farm, Hort. Res. Institute, Mansoura, Dakahlia Governorate, Egypt (+ 7m altitude, 30^o 11^- latitude and 28^o 26^- longitude), during seasons of 2012 and 2013, to study the effect of slow release-N Sulfur coated urea "SCU" rats, and foliar spray with some micronutrients levels as well as their interaction on productivity, and quality of sweet potato cv. Abees. The most important finding could be summarized as follows:
In general, results showed that the plants sprayed with mixture of micronutrients were better than those of the unsprayed ones. Increasing the foliar applied mixture of micronutrients concentration from 0 to 50 ppm significantly increase plant height, plant dry weight and leaves area/plant as well as total yield, marketable yield and weight, length and diameter. Moreover, foliar application of mixture of micronutrients significantly increased concentrations of N in the first season only. In addition, reducing sugar and carotene were increased in both seasons. Foliar spray with mixture of micronutrients at 50 ppm had the most interesting observation in the enhancing of most studied characters.
On the other hand, application of slow release nitrogen fertilizers rates gave rise to significant increases in plant height, number of branches/plant; plant dry weight, leaves area/plant ratio, total yield, marketable yield and weight, length and diameter as well as chemical and organic constituents on tuber root of sweet potato. The application of 60 kgN/fed. sulfur coated urea "SCU", was superior on all studied characters.
The combined treatments of sprayed with mixture of micronutrients and sulfur coated urea "SCU" were generally more effective on the most studied parameters than single ones. The best results were obtained by foliar sprayed with micronutrients at 50 ppm and application with 60 kg N/fed. sulfur coated urea "SCU" gave the highest values of plant growth, yield and its components as well as chemical and organic constituents in both seasons compared with the other treatments. Therefore, this treatment could be recommended for raising sweet potato productivity and quality under similar conditions to this work.