GOOD fertilizer management is critical for high yielding, quality and profitability of sugar beet. This work was carried out at Mallawi Agric. Res., Station, El-Minia Governorate, Egypt, during 2012/2013 and 2013/2014 seasons to study effect of three application dates of yeast, i.e., 80, 110 and 140 days of sowing and three levels of potassium fertilizer, i.e., 0, 24, 48 kg K2O/fad on vegetative, physiochemical, yield traits and profitability of sugar beet. A split plot design with four replications was used in both seasons and Monetbianco cultivar was sown.
The obtained results indicated that addition time of yeast or/and level of potassium fertilizer (kg K2O/fad) exhibited a significant effect on vegetative characters of beet roots. Physical properties of beet roots, such as SR (Sugar recovery) %, QZ (Quality index) % and SL (Sugar loss) %, chemical constituents (pol (polarization) %, K, Na and a-N determined as milliequivalent/100 g beet), except the 2nd season for Na content of beet roots not reached significant level, and productivity traits of sugar beet, i.e., roots yield and recoverable sugar yield (ton/fad) in both growing seasons and combined.
The interaction between addition time of yeast with K-fertilization level was significant on vegetative traits of sugar beet, physical properties of beet roots, chemical constituents and productivity traits of sugar beet.Yeast addition at age 80 days was markedly increased the total return per fad by 27.64 and 26.85% and net profit by 60.80 and 58.64% as well as sugar yield in ton/1000m3 by 7.14 and 0.84 % compared with applying yeast at ages 110 and 140 days, respectively.
In general, it can be concluded from the results that applying yeast at age 80 days from sowing with 24 kg K2O/fad could be recommended because it achieved the maximum values of SR% (16.27%), QZ (86.99%) and pol % (18.71), while it contained the lowest values of SL% (2.44 %) ɑ-N (1.24 milliequivalent/100 g) and Na (1.31 milliequivalent/100 g) contents. While, the highest values (4.73 and 4.78 ton/fad) for recoverable sugar yield of sugar beet was recorded with adding yeast at ages 80 and 140 days from sowing with 24 kg K2O/fad, respectively.