Epsilon Archive for Student Projects

Abstract

The genus of Eucalyptus has become the most planted hardwood tree species and Brazil is the world’s largest producer. Intensive management including fertilizer application is practiced to maximize productivity and reduce rotation length. Seasonal rainfall and changing rainfall patterns have also led some foresters in Brazil to adopt the use of super absorbent hydrogels which improve water availability for the seedlings during the establishment phase.

Arginine phosphate, marketed under the trade name arGrow® granular by Arevo, has potential to improve establishment of Eucalyptus. This technology is classified as a biostimulant, rather than a fertilizer because the amino acid arginine, an organic nitrogen form, supports root development and mycorrhizal associations that can in turn support improved drought tolerance and nutrient uptake.

The aim of this study was to describe growth responses to arginine phosphate when applied directly to the root plug of Eucalyptus grandis seedlings at irrigation levels that mimic the range of field rainfall in Brazil’s State of Bahia. Under greenhouse conditions, two pilot studies preceded a main experiment. A multi-factorial experimental design included three irrigation levels, four nitrogen input levels applied as arginine phosphate and the presence/absence of hydrogel.

Co-application of hydrogel together with arginine phosphate increased the survival rate and improved growth of Eucalyptus grandis seedlings compared to applications of hydrogel or arginine phosphate alone. Some seedlings treated with arginine phosphate without a co-application of hydrogel presented symptoms of drought stress within 7 days in a dose-dependent manner and observed most severely at the low irrigation levels in a way that is consistent with osmotic stress. Arginine phosphate treatment increased foliar nitrogen content and leaf area in a dose-dependent manner. Collar diameter, height, field roots biomass and total plant biomass did not respond significantly in a dose-dependent manner after the five-week treatment but it would be likely after a longer growth response period.