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This study examines the effect of multiple spray applications of Apogee on shoot growth and whole-canopy photosynthesis (WCPn) rate in young, bearing apple trees. Apogee increased fruit numbers and reduced shoot growth and inconsistently reduced leaf area but the reduction in photosynthetic area did not result in reduced WCPn or a detrimental effect on the fruit number:fruit size relationship. Since WCPn was not affected when leaf area was reduced by Apogee treatment, it suggests a greater photosynthetic efficiency of leaves on Apogee treated trees due to reduced shading. The use of Apogee for canopy management may produce a side-effect of increasing fruit set, which may be managed through a crop thinning program.
by diffusion of PAR into the interior of the canopy ( Glenn and Puterka, 2007 ; Rosati et al., 2007 ; Wünsche et al., 2004 ). Whole canopy photosynthesis can be increased by the combination of reduced canopy temperature and increased interior
Processed-kaolin particle films (PKPFs) are used commercially in large quantities on horticultural crops to repel insects, and reduce heat stress and solar injury of fruit. Our studies determined the effect of two processed-mineral particle film materials (kaolin and calcium carbonate), on whole plant carbon assimilation, water use efficiency, yield, mean fruit weight and quality in `Empire' apple [(Malus ×sylvestris (L.) Mill var. domestica (Borkh Mansf.))] over a four-year period. The application of a PKPF reduced canopy temperature, and probably reduced environmental stress, resulting in increased mean fruit weight and red color in two of the four years of the study. Whole canopy carbon assimilation studies indicated increased carbon assimilation only under conditions of high air temperature. The PKPF sprayed leaves also had reduced water use efficiency; likely due to increased stomatal conductance associated with reduced leaf temperature. Calcium carbonate had none of the positive effects of PKPF and reflected more photosynthetically active radiation (PAR) than the PKPF.
). Theoretically, quantum yield of a dense plant canopy should be more equalized under green light as a result of increased light interception by lower leaves, which could potentially increase whole-canopy photosynthesis and, subsequently, increase plant yield. In
To initiate photosynthetic studies of sweet cherry (Prunus avium L.) canopy architectures and cropping management under high light and temperature conditions (Yakima Valley, Wash.), we developed a whole-canopy research cuvette system with a variable airflow plenum that allowed different patterns of air delivery (in concentric circles around the trunk) into the cuvette. Air and leaf temperatures (Tair and Tleaf, respectively) were determined at four horizontal planes and four directional quadrants inside cuvette-enclosed canopies trained to a multiple leader/open-bush or a multiple leader/trellised palmette architecture. Air flow rate, air delivery pattern, and canopy architecture each influenced the whole-canopy temperature profile and net CO2 exchange rate (NCER) estimates based on CO2 differentials (inlet-outlet). In general, Tair and Tleaf were warmer (≈0 to 4 °C) in the palmette canopy and were negatively correlated with flow rate. The response of Tair and Tleaf to flow rate varied with canopy position and air delivery pattern. At a flow of 40 kL·min-1 (≈2 cuvette volume exchanges/min), mean Tair and Tleaf values were 2 to 3 °C warmer than ambient air temperature, and CO2 differentials were 15-20 μL·L-1. Tair and Tleaf were warmer than those in unenclosed canopies and increased with height in the canopy. Carbon differentials declined with increasing flow rate, and were greater in the palmette canopy and with a less dispersed (centralized) delivery. Dispersing inlet air delivery produced more consistent values of Tair and Tleaf in different canopy architectures. Such systematic factors must be taken into account when designing studies to compare the effects of tree architecture on whole-canopy photosynthesis.
458 Glenn, D.M. Miller, S.S. 2005 Effects of Apogee on growth and whole-canopy photosynthesis in spur ‘Delicious’ apple trees HortScience 40 397 400 Goulart, B.L. 1989 Growth and flowering of greenhouse-grown red raspberry treated with plant growth
Glenn, D.M. Miller, S.S. 2005 Effect of Apogee on growth and whole-canopy photosynthesis in spur ‘Delicious’ apples trees HortScience 40 397 400 Greene, D.W. 1999 Tree growth management and fruit quality
Glenn, D.M. Miller, S.S. 2005 Effect of Apogee on growth and whole-canopy photosynthesis in spur ‘Delicious’ apples trees HortScience 40 397 400 Greene, D.W. 1999 Tree growth management and fruit quality
reduced canopy temperature and reduced heat stress leading to increased whole canopy photosynthesis. Increased PAR within the canopy was measured ( Tables 1 , 2 , and 3 ) but was not a large addition of light to the energy budget. An additional
Effects of dose and time of application of GA 4+7 on russeting, fruit set and shape of Golden Delicious apples Scientia Hort. 14 307 314 Glenn, D.M. Miller, S.S. 2005 Effects of Apogee on growth and whole-canopy