Adensamento de plantio para laranjeira Valência enxertada em citrandarins

Abstract

The cultivation of Valencia sweet orange has faced significant phytosanitary challenges, especially due to the spread of huanglongbing. This scenario has favored the use of less vigorous rootstocks associated with the adoption of high-density planting. Among the available rootstock options, citrandarins have stood out for producing more compact trees with good productivity. In this context, the objective of this study was to evaluate how different plant spacings influence the vegetative development of Valencia sweet orange trees grafted onto different citrandarins. Seedlings were planted under a minimum tillage system, with soil preparation restricted to the planting rows and an inter-row spacing of 6.0 meters. The experiment was arranged in a randomized block design in a split-plot scheme, with four in-row spacings (3.0 m, 2.5 m, 2.0 m, and 1.5 m) assigned to the main plots and four rootstocks [IAC 3152 Itajobi (152), IAC 3155 (155), IAC 3073 Barretos (73), and IAC 3026 Santa Amélia (26)] assigned to the subplots. There were three replicates, each consisting of five plants. Evaluations included vegetative growth, leaf gas exchange (photosynthesis, transpiration, stomatal conductance, intercellular CO₂ concentration, and water use efficiency), and root system development. The 3.0 m spacing favored canopy diameter and volume growth as well as root development, with emphasis on rootstocks 152 and 26. Rootstock 73 showed greater physiological efficiency under high-density planting (1.5 m), with lower transpiration, stomatal conductance, and internal CO₂ concentration, without compromising photosynthesis, indicating a water-saving strategy. It is concluded that rootstock selection should consider not only its general adaptation, but also its physiological behavior and growth pattern under different planting densities, seeking combinations that maximize vegetative development, resource use efficiency, and adaptation to the adopted management system.