Comparison of SHD and Open-Center Training Systems in Almond Tree Orchards cv. ‘Soleta’

Abstract

The increase in the demand for almonds, the development of novel self-fertile and late-flowering varieties, and the establishment of plantations in new irrigated areas have led to significant progress in the productive techniques of almond tree cultivation. One of the most important has been the increase in planting density, due to the development of dwarfing rootstocks. This paper presents a comparison between two training systems with ‘Soleta’ almond cultivar: a super high density (SHD) system using Rootpac-20 dwarfing rootstock versus an open-center training system using GF-677 rootstock. To this end, several parameters related to chlorophyll content (fluorescence and SPAD) and light interception (from photosynthetically active radiation (PAR) measurements) were monitored throughout two vegetative cycles, and other productive conditions (flowering, fruit set and production) were tracked at specific times of the cycle. The open-center system resulted in higher PAR interception than the SHD system, but also in the presence of poorly illuminated fractions of the canopy. Differences were observed between both systems in terms of average fruit weight and yield per canopy volume. Lower yields were obtained in SHD system than in open-center, which may be significantly increased by adapting the inter-row spacing. However, the degree of efficiency in the use of resources or productive inputs, such as irrigation, was favorable to the new SHD training system, so its potential to become a reference system in modern plantations (using over-the-row harvesters similar to those used for vine and olive trees) seems promising.

Row Orientation and Canopy Position Affect Bud Differentiation, Leaf Area Index and Some Agronomical Traits of a Super High-Density Almond Orchard

“…With west exposure, the light is captured in the afternoon, when the physiological condition of trees suffers from closed stomata. Higher afternoon temperature could also lead to a reduction in photosystem efficiency [20]. In the top layer the situation is different, with the highest PAR on the west side, decreasing towards north.…”

Intercepted Photosynthetically Active Radiation (PAR) and Spatial and Temporal Distribution of Transmitted PAR under High-Density and Super High-Density Olive Orchards

“…Below 20% of PAR there is a significant increase in fruit abscission [18], while below 10% PAR, leaf senescence occurs [22]. These concepts were discussed also by Casanova-Gascon et al [34] who compared SHD vs. open center almond trees. Based on their transmitted light measurements, these authors speculated that bottom-canopy leaves in the SHD system had better illumination.…”

Remote Sensing Energy Balance Model for the Assessment of Crop Evapotranspiration and Water Status in an Almond Rootstock Collection

“…In almonds [ Prunus dulcis (Mill.) DA Webb], with the recent introduction of high-density planting systems, particular attention has been paid to using dwarf rootstocks in order to control canopy vigor and facilitate mechanical harvesting ( Pinochet, 2009 ; Casanova-Gascón et al, 2019 ). In addition, with the introduction of new dwarfing rootstocks and hybrids coming mainly from the peach sector, the paradigm has changed since information about their response to drought or a limited water supply is scant.…”