Effects of sewage sludge and length on initial growth of guava seedlings

Substrate and light intensity exert influence on the quality of seedlings produced by increasing plant nutritional efficiency and growth. The objective of this work was to study the emergence and early growth of guava seedlings (Psidium guajava L.) in substrate enriched with sewage sludge and under different light intensities. In the conduction of this work, guava seeds of the cultivar Pedro Sato were used and five substrates formed by dystrophic Red Yellow Latosol, washed sand, and sewage sludge: S1-soil + sand (Control); S2 - soil + sand + silt (40 t ha-1); S3 - soil + sand + silt (80 t ha-1); S4 - soil + sand + sludge (120 t ha-1); S5 - soil + sand + sludge (240 t ha-1); and S6 - soil + sand + sludge (480 t ha-1). Each experimental plot consisted of four repetitions of 25 seeds for the analyzed emergence (%) and emergence speed index. For fresh and aerial part dry mass (mg L-1), root dry mass (mg L-1), root volume (cm3 plant-1), number of leaves, levels of chlorophyll a, b and total chlorophyll each experimental plot consisted of four repetitions of 16 seeds. The production of guava seedlings with sewage sludge should be conducted with the dosages of 240 and 480 t ha-1. Shading with two screens is recommended for the production of guava seedlings. Key words: Biosolids, emergency, luminous intensity, Psidium guajava L., residues.