An experiment was executed at the Horticultural orchard and the laboratory of fruit section, Faculty of Agriculture, Assiut University, Assiut, Egypt during three successive seasons of 2005, 2006 and 2007 on Balady mandarin trees. The study aimed to investigate the effect of biofertilizers, micro nutrients and their different combinations on the yield and fruit quality as well as the nutrients status in the soil and leaves associated with these treatments. Biofertilizers including Phosphorien, Nitrobien and Potassien were applied at a rate of 250g from each type/tree every season or in combination with chelated elements including Fe, Mn, Zn and Cu. Micronutrients were twice sprayed at 60 ppm on mid March and June.
The results revealed that mandarin yield (kg/tree) significantly increased by 21.7%, 13.1 and 19.0% over the control as a result of applying the biofertilizers alone, a combination of the biofertilizers with micronutrient, and micronutrients spraying alone, respectively (as an average of the three seasons). The study also indicated that the early harvesting on mid December was superior respecting the yield in comparison with the late harvest date on mid February. The results also revealed that all the treatments caused a significant increase in the fruit weight. They also mostly had insignificant effect on the fruit chemical properties.
Applying biofertilizers alone or combined with micronutrients, and the micronutrients alone increased N, P and K content in the leaves as compared to the control. The increment percentages were 9.09%, 9.56% and 11.48% for N%, 20.26%, 15.68% and 30.06% for P, and 42.85%, 56.04% and 56.04% for K, in relation to the later treatments, respectively. Also, micronutrients content in the leaves were enhanced due to the biofertilizers and micronutrients foliar application. Data also revealed that, all the nutrient concentrations in the spring leaves surpassed that in the summer leaves.
The calculated yield/feddan (early harvest date) due to using the biofertilizers (about 9 tons/feddan) removed 6.49, 1.72, and 11.95 Kg/fed of N, P and K, respectively. While, the application of the recommended dose of N, P and K removed 5.35, 1.70 and 13.82 Kg/fed of N, P and K, respectively.