Effect of combination between Bio and chemical fertilization on vegetative growth, yield and quality of Valencia orange fruits (original) (raw)

Yield and quality of fruits of Valencia orange are influenced by using an N fertilization, the excessive use of N fertilizer can accumulate harmful nitrate in fruit and soil. During the two successive seasons 2011 and 2012 this study was carried out on 12 years old Valencia orange trees budded on sour orange cultivated in the experimental farm of faculty of Agricultural south valley Univ., with clay Loam soil texture, at Qena Governorate. to evaluate the behavior of three kind of biofertilizers namely Azotobacter choococcum, Bacillus megaterium and Bacillus circulans, adding 140 or 180 units of nitrogen combined with 120 units of potassium and their effects on vegetative growth, leaf mineral content, yield and fruit quality. The obtained results showed that, the growth parameters increased significantly when added Bacillus circulans with 180 units of nitrogen than adding the same biofertilizer with 140 units of nitrogen. Whereas, adding 140 units of nitrogen/feddan without biofertilizer gave a lower effect for the same traits. The increment of yield / trees was about 18.32 % and 17.97 % with Bacillus circulans, 9.08 % and 8.54 % with Bacillus megaterium while the lowest values observed in Azotobacter which were 6.31 % and 6.60 % during the first and second seasons with 180 units of nitrogen. Chemical composition of fruit juice such as T.S.S, Acidity, T.S.S, Acid ratio and sugar were increased under the lower level of nitrogen, except V.C. and Total carotenoids. Hence, it can be concluded that using Bacillus circulans under the highest and the lower levels of nitrogen combined with 120 units of potassium was very effective than the other kind of biofertilizers.