Efficacy of K-Humate, Compost and Biofertilizer Application as Well as Cutting Number on Yield and Quality of Stevia (Stevia rebaudianaBertoni) as Natural Sweetener

Stevioside is natural sweetener isolated from the leaves of plant stevia and it is up to 300 times sweetener than sucrose, since it is a sweetener with no caloric value and with proven non-toxic effect on human health. Steviol glycosides are used as a sweetener in many industrial foods, such as soft drinks or fruit juices. So, two field experiments were conducted at Mallawi Agricultural Research Station, El-Minia Governorate during 2014 and 2015 seasons to deduce the effect of different sources of nutrient, i.e. Control (80 kg N fed^-1), K-humate + (40 kg N fed^-1), biofertilizer +(40 kg N fed^-1) and compost + (40 kg N fed^-1)] and number of cutting , i.e. 1^st , 2^nd  and 3^rd cutting on yield and quality of stevia (Stevia rebaudianaBertoni) under Middle Egypt conditions. The obtained data pointed out that different sources of nutrient had a significant effect on plant height, fresh plant weight, dry plant weight, fresh leaves weight/plant, dry leaves weight/plant, N, P and K % of stevia leaf, fresh biomass yield, dry biomass yield , fresh leaves yield, dry leaves yield and fresh stem yield, total stevioside % (St %), rebaudioside A% (Rb%), stevioside yield and rebaudioside A yield of stevia in two growing seasons.
The studied cutting number of stevia had a significant influence on plant height, fresh plant weight, dry plant weight, fresh leaves weight/plant, dry leaves weight/plant, dry leaves weight: dry stem weight, P % of stevia leaf, fresh biomass yield, dry biomass yield, fresh leaves yield, dry leaves yield  and fresh stem yield and dry stem yield of stevia, rebaudioside A%, total stevioside yield (kg/fed) and rebaudioside A yield (kg/fed) of stevia rebaudiana in two growing seasons. From the present study, it may be concluded that the application of compost at 2.0 ton/fed+(40 kg N fed-1) with 3^rd cutting was the best treatment for improving the yield and quality of stevia (Stevia rebaudianaBertoni) and is advisable because it is achieved the highest value of rebaudioside A(102.80 kg/fed) of stevia. This helps in reducing the great gap in sugar production, which amounted to 0.7 million tons between production and sugar consumption at the national level production under the experimental conditions.