Abstract
As apple orchards have transitioned to high-density plantings, proper training systems are required to manage increased leaf area. Leaf area index (LAI) is defined as the ratio between leaf area to ground area (m2/m2) and can infer orchard health, light relationships and productivity. New technologies enable rapid assessments of LAI and light interception (LI) in the orchard. In this study, LAI, LI, and productivity were assessed across two training systems (Spindle and V), two rootstocks (Geneva 41® (G41) and Malling 9—Nic29 (Nic29)) and two pruning techniques (“click” and bending) in 2016 and 2017. The objective of this study was to determine a management strategy for “WA38” to meet optimal levels for LAI (1.2–2.0) and light interception (65–75%). Higher light interception was measured in V compared to Spindle and in G41 compared to Nic29 in both years. Minimal differences in LAI and light interception were detected across pruning techniques. In “WA38” the “click” technique maintained more consistent yields than bending. In both years, the Spindle-Nic29-“click” combination maintained optimal thresholds for LAI (1.93 and 1.48), light interception (66% and 68%) and consistent yields. This sequence helps mitigate “blind wood” and alternate bearing, while optimizing leaf area and light in “WA38”.
Highlights
Different training systems present various light interception (LI) levels and light distribution across the canopy [1]
This study evaluates the impact of training systems, rootstocks and pruning techniques on Leaf area index (LAI), LI, and production in “WA38.”
(m2 /m2 ), light interception (LI) fruit count, yield, average fruit weight (g) and production (MT/ha) for “WA38” trees grown in Wenatchee area in Washington State in 2016
Summary
Different training systems present various light interception (LI) levels and light distribution across the canopy [1]. Tree training influences the development, position, and crotch angle of branches, and their ability to intercept light, which impacts yield and fruit quality [2]. Planting densities in pome and stone fruit orchards have increased in the last decade and it is crucial to properly manage and manipulate the canopy to maintain the trees’ efficiency [4,5,6]. Reduced spacing can lead to increased shading within the row, as well as in proximate rows if the height of trees is not regulated [7,8]. Both in height and volume as to reduce the deleterious effects of shading on flower bud induction and fruit development [12]. Training systems need to be designed according to cultivar selection, planting density, and the light available in the growing region [3]
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