IrrigaÇão com águas salinas e adubaÇão nitrogenada na produÇão de mudas mamoeiro "Formosa".

The occurrence of long periods of drought and the annual irregularity of precipitation in the semi-arid region of the Brazilian Northeast make irrigation practice essential to ensure safe agricultural production, however, the available water sources are not always of good quality. In this way, the objective of this work was to evaluate the effects of irrigation with waters of different saline levels associated with nitrogen rates on the growth of 'Formosa' papaya seedlings under northeastern semiarid conditions. The experiment was carried out in plastic bags under protected environment conditions at the Center of Science and Technology Agrifood of the Federal University of Campina Grande, Pombal - PB campus. The experimental design was a randomized block design, in a 5 x 4 factorial scheme, with four replications, being the treatments composed of five levels of electrical conductivity of the water (EC, 0.3, 1.1, 1.9, 7 and 3.5 dS m-1) and four nitrogen doses (70, 100, 130 and 160% N recommended). The electrical conductivity of irrigation water from 0.3 dS m-1 negatively affected plant height and dry stem biomass. It is observed that the dose of 70% of N and of 100% provided, respectively, greater dry matter production of root and number of leaves. No significant effect was observed for the variables stem diameter and dry stem biomass submitted to different CEa and nitrogen fertilization; As well as, there was no interaction between the factors (CEa x Fertilization with N) on the growth of the seedlings. The variables NF, FFF, FSF, FSR presented tolerance to the increase of electrical conductivity of irrigation water. [ABSTRACT FROM AUTHOR]