Chemical Evaluation of Some Stevia (Stevia rebaudiana, Bertoni) Varieties of under Different Nitrogen Fertilization Levels

. A .A. Tantawy * .A.E. Attia **Nareyman. N. Kenawy. **.

Abstract

Two field experiments were carried out at agricultural research center, Giza, Egypt during 2015/2016 and 2016/2017 seasons to study the effect of nitrogen fertilizer levels (20, 30 and 40 kg N/ fed/cut.) on some stevia varieties (china1, Egy1, spanti and shou2). The highest nitrogen rate of 40 kg. N /fed /cut was significant in all studied yield andChemical characters and gave the highest values of stevioside%. recorded (6.09 and 6.62%), ,rebaudioside A% ( 7.23 and 8.04%), Stevioside kg /fed ( 238.9 and 286.1 kg ) and rebaudioside A kg /fed (287.2 and 350.5 kg) ), respectively as compared with the other two nitrogen treatments in both seasons. Stevia Varieties were significantly different in all studied yield characters. china 1 Varieties gave the highest values of stevioside% (6.83 and 7.34 %), rebaudioside A% ( 8.44 and 9.26 %), rebaudioside A kg /fed(300.8 and 363.2 kg ), respectively of all studied yield and chemical characters except for dry leaves yield kg/fed where Egy1 varieties gave the highest values in the first and second seasons. .Concerning the effect of the interaction between nitrogen fertilizer levels and stevia varieties on yield and chemical characters, nitrogen fertilizer level of 40 kg N/ fed/cut applied to china1 varieties gave the highest values in all studied yield and chemical composition except for dry leaves yield (kg/fed) where Egy1 varieties and nitrogen fertilizer level of 40 kg N/ fed/cut gave the highest values in the first and second seasons.

Key words

stevia, nitrogen fertilizer, varieties, stevioside, rebaudioside -A .