INFLUENCE OF PHOSPHORUS AND NITROGEN FERTILIZERS ON ATTAINMENT OF BUDDING SIZE OF CITRUS SPECIES

Field experiment was conducted at the Teaching and Research Farm, Federal University of Agriculture, Abeokuta to evaluate the influence of fertilizer types/rates on attainment of budding size responses of Citrus reticulata var Cleopatra mandarin. Three months old Citrus seedlings were treated with Phosphorus at three rates of 0, 12.5 and 25kg/ha single super phosphate (SSP) and Nitrogen at seven rates of 0, 12.5, 25 and 50kg/ha NPK with additional N rates at 12.5kg/ha NPK + 12.5kg/ha urea, 25kg/ha NPK + 12.5kg/ha urea and 50kg/ha NPK + 12.5kg/ha urea arranged in a completely randomized design replicated three times. The results showed that there was no significant difference in Nitrogen application rates. However, with exception of no significant difference in leaf area at 2 – 8 weeks after transplanting (wap), significantly (p<0.05) higher response of Citrus was observed for P at 25kg/ha SSP but not different from unfertilized control (0kg/ha). The lower growth and nutrient uptake responses observed for P at 12.5kg/ha SSP could be due to the effect of nutrient antagonism. Interaction effects between P and N occurred only for plant height at 14 wap and stem girth at 10 and 14 wap. In summary, while P influenced growth better than N indicating that higher rates of N might be needed to improve seedling growth of Citrus in nursery, Citrus plants responded differently to fertilizer P and N application rates.