Two field experiments were carried out during the two successive seasons of 2016/17 and 2017/18 at Nubassed sector, West Nubariya, Egypt, (latitude 30° 47′N and longitude 30° 25′ E), El-Beheira Governorate, Egypt to study the influence of mineral K-fertilizer and bio-K (containing Potassium Solubilizing Bacteria KSB-Frateuria aurantia) on sugar beet physiological, qualitative and productivity attributes. Randomized Complete Block Design was used in a split split-plot distribution, with three replications. Three polygerm sugar beet varieties namely MK 4016, Samba and Gloria, allocated in the main plots, three potassium fertilizer rates (0, 24 and 48 kg K2O/fed) randomly distributed in the sub-plots and two KSB treatments (KSB0: uninoculated and KSb1: inoculated with bacteria) randomly applied in the sub-subplots.
The most important results indicated that; Gloria variety significantly surpassed the other two varieties in root length, root diameter, root fresh weight, root yield (ton/fed) and recoverable sugar yield (ton/fed). Growing sugar beet under 48 kg K2O/fed recorded the highest values of LAI (at 135 days), root length, root diameter, leaf K content, sucrose %, root K+ content, sugar loss in molasses%, root fresh weight, root yield, top yield, recoverable sugar yield, recoverable sugar percent and harvest index in comparing with 0 and 24 kg K2O/fed. The inoculation of sugar beet with KSB significantly increased root length, root diameter, sucrose%, root fresh weight, root yield, top yield and recoverable sugar yield compared with uninoculated treatment.
The interaction between potassium fertilizer rates × inoculation with KSB showed that, there were insignificant differences between applying 24 kg K2O/fed × inoculation with KSB and with 48 kg K2O/fed × uninoculation on root fresh weight, sucrose% and recoverable sugar yield in both seasons.
As a result of the present study it might be concluded that, growing sugar beet under the application of 48 kg K2O/fed × inoculation with KSB produced the highest root length, root diameter, sucrose%, root fresh weight, root yield, and recoverable sugar yield in both seasons of this study.