Articles
The physiological basis of orchard system performance with respect to light interception and light conversion efficiency
Article number
1346_27
Pages
207 – 218
Language
English
Abstract
A study we performed in 1991 showed that 68% of the variation in cumulative yield of various apple orchard systems was explained by the amount of light (MJ) intercepted by the canopy and 11% was explained by the efficiency of converting light energy into fruit (g MJ‑1). The amount of light intercepted by the canopy is controlled by tree shape (V vs. vertical) and the ratio of tree height to row spacing, while the efficiency of energy conversion to fruit is controlled by several factors, including rootstock, tree vigor, pruning severity, crop load, and climate.
Results from our work show that early orchard life light interception is tightly related to tree planting density and any system that uses lower tree density as a way to reduce costs also has lower light interception.
Our work has shown that V shaped canopies intercept more light than vertical canopies.
The lower light interception of vertical wall systems can be partially overcome by increasing tree height of vertical canopies.
Another result has shown that efforts to produce narrow fruiting walls (2-dimensional canopies) result in lower light interception and a yield penalty compared to 3-dimensional canopies unless between row spacing of the 2-dimensional system is reduced beyond currently acceptable row spacings.
Reflective films on the ground underneath the canopy can increase light interception by 5-7%. Rootstock is the major factor influencing conversion efficiency, but in some cases, rootstocks with high conversion efficiency dont have high light interception at a given spacing because they have too little vigor to fill the allocated space and thus have lower cumulative yield.
In recent years new training systems, rootstocks, and pruning systems have been developed, but often they have not been evaluated rigorously with respect to early orchard life and lifetime light interception and conversion efficiency.
Results from our work show that early orchard life light interception is tightly related to tree planting density and any system that uses lower tree density as a way to reduce costs also has lower light interception.
Our work has shown that V shaped canopies intercept more light than vertical canopies.
The lower light interception of vertical wall systems can be partially overcome by increasing tree height of vertical canopies.
Another result has shown that efforts to produce narrow fruiting walls (2-dimensional canopies) result in lower light interception and a yield penalty compared to 3-dimensional canopies unless between row spacing of the 2-dimensional system is reduced beyond currently acceptable row spacings.
Reflective films on the ground underneath the canopy can increase light interception by 5-7%. Rootstock is the major factor influencing conversion efficiency, but in some cases, rootstocks with high conversion efficiency dont have high light interception at a given spacing because they have too little vigor to fill the allocated space and thus have lower cumulative yield.
In recent years new training systems, rootstocks, and pruning systems have been developed, but often they have not been evaluated rigorously with respect to early orchard life and lifetime light interception and conversion efficiency.
Publication
Authors
T.L. Robinson
Keywords
Malus × domestica, spur leaf light interception, pruning, rootstock, crop load
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