Using Various Forms of NPK Fertilisers to Improve the Growth and Fruiting of Washington Navel Orange under Qalyoubia Governorate Conditions

This investigation was carried out to study the effects of the different applied mineral, organic and natural alternative fertilizers levels supplemented with or without some bio-stimulants fertilizers on some vegetative growth measurements, nutritional status and some fruiting aspects parameters of “Washington navel” orange trees during the two consecutive seasons of 2022 and 2023. The obtained data revealed obviously that all treatments in this study resulted in a positive increase in all investigated vegetative growth measurements. Furthermore, all studied fertilization treatments significantly increased fruiting aspects parameters i.e., (fruit set %, tree yield either in kg or number of fruits per tree and yield as ton per feddan) whereas, decreased percentage of fruit drop during the two experimental seasons. Moreover, leaf nutrients composition of some macro elements (N, K, Ca and Mg) and micro nutrients (Fe, Mn and Zn) were improved generally from the standpoint of statistic by all investigated fertilization treatments, while leaf phosphorus (P) content did not responded from the standpoint of statistic to any fertilization treatments, since the response was completely absent and the differences were insignificant during the two seasons of study.Undoubtedly, it could be concluded that, all investigated fertilization treatments under study resulted in a significant and beneficial effects on most of parameters of Washington navel orange trees. However, the treatment of (100 % NPK as mineral, organic and natural alternative) combined with bio-fertilizers exhibited statistically the best and the most effective for increasing and improving both vegetative growth and fruiting aspects parameters and nutritional status