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Ignasi Iglesias and Simó Alegre

, Bourne, MA). These were installed 1.2 m aboveground level, within the canopy, and at the center of one block per treatment were fruit color (colorimeter) was measured. Light distribution within the canopy. The effect of the reflective film on light

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Ray A. Allen and Curt R. Rom

Light distribution in two cultivars on three dwarfing rootstocks in three high-density apple tree training systems was measured in the sixth leaf beginning at full bloom and continuing through the season. Training system had a significant effect on light penetration into the lowest point of the canopy (measured at 0.5 m), with the slender spindle being significantly darker than either the central leader or the vertical axis, although all three systems were below the threshold value of 30% full sun (FS) needed to maintain productivity for most of the season. Cultivar had no significant effect; however, trees of both `Jonagold' and `Empire' fell below 20% FS early in the season and remained there until late in the season. Rootstock had the greatest effect, with trees on M9 and M26 being significantly darker in the lower canopy than trees on Mark. Trees on M26 and M9 fell below 10% FS early in the season and remained there, while trees on Mark never fell below 20% FS.

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Jon M. Clements and Joseph F. Costante

A randomized complete block study was initiated in 1991 in a fifteen year old `Rogers Red McIntosh'/9-106 interstem orchard to investigate the effect of three dormant pruning regimes- an unpruned control, selectively thinned, and heavily structured or “tiered”, on tree canopy light distribution and fruit and spur quality. Fruit quality parameters being measured for the 1991 and 1992 harvests include skin color (% red blush), weight (g.), flesh firmness (kg.), soluble solids concentration (% Brix), and packout (% fancy grade). Pruning treatment effect on fruit spur quality, in terms of spur bud diameter (mm.) and spur efficiency (leaf dry weight/spur), is also being evaluated at time of harvest. Light distribution is being measured (% PAR, umol/s/m2.) within the tree canopy from petal fall through harvest. Preliminary findings indicate there is a difference in tree canopy light distribution and some fruit quality measurements, including red skin color, between pruning regimes. Complete analysis of results from 1991 will be presented.

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Todd C. Einhorn, Janet Turner, and Debra Laraway

improve production efficiencies ( Elkins et al., 2012 ). The reliance on heading cuts during dormancy to control tree size encourages excessive early and midseason vegetative growth, which, in turn, limits intracanopy light distribution (Einhorn, personal

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D.C. Elfving, I. Schechter, R.A. Cline, and W.F. Pierce

Mature `Macspur McIntosh'/MM.106 apple trees (Malus domestica Borkh.) trained to the central-leader (CL) tree form were converted to the palmette-leader (PL) tree form in 1987 by removal of east- and west-oriented scaffolds in the upper canopy. Control trees were pruned to maintain the CL form. Dormant pruning in subsequent seasons maintained either tree form. No summer pruning was done. Canopy light levels along horizontal transects 1 m above the soil and vertical transects, both through the center of the canopy, were unaffected by tree form or transect direction. Yields were significantly lower for PL trees in 1987 and 1989, while yield efficiency was reduced in PL trees in all 3 years. Fruit size, trunk cross-sectional area growth, and foliar macronutrient content were unaffected by tree form. Fruit color development in both the upper and lower halves of the canopy was not influenced by tree form during the study.

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Arend-Jan Both, Bruce Bugbee, Chieri Kubota, Roberto G. Lopez, Cary Mitchell, Erik S. Runkle, and Claude Wallace

of low- and high-wattage lamps. We propose that measurements be made and reported in wavelength intervals no larger than 3 nm. Light distribution. For most commercial plant growth applications, lamp installations are designed to provide a uniform

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D.C. Elfving, I. Schechter, R.A. Cline, and W.F. Pierce

Mature `Macspur McIntosh'/MM.106 trees trained to the CL tree form were converted to the PL tree form in 1987 by removal of east- and west-oriented upper scaffold limbs. Control trees were pruned to maintain the CL form. Dormant pruning in later years maintained either tree form. No summer pruning was used in this study. Canopy light levels along horizontal transects at one m above the soil and vertical transects, both through the center of the canopy, were unaffected by tree form or transect direction. Yields were significantly lower for PL trees in 1987 and 1989, while yield efficiency was reduced in PL trees in all 3 years. Fruit size, trunk cross-sectional area, and foliar macro-nutrient content were unaffected by tree form during this study. Fruit color development in both the upper and lower halves of the canopy was uninfluenced by tree form.

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T.M. DeJong and K.R. Day

The relationships between shoot light exposure in one year and the flower and fruit production characteristics of those shoots the following year were indirectly investigated in summer pruned and nonsummer pruned peach [Prunus persica (L.) Batsch.] trees by evaluating leaf characteristics (leaf N and dry matter content per unit leaf area; Na and Wa, respectively) on tagged shoots during one season and the flowering and fruiting characteristics during the subsequent season. There were significant positive linear relationships between leaf Na and Wa on shoots in one year and flower and fruit production per unit shoot length during the subsequent year. Summer pruning had relatively little influence on these relationships. There was no apparent relationship between percent fruit set in the spring and light exposure of the shoots the previous summer. Following dormant pruning and commercial thinning, trees summer-pruned the previous year had higher yields than nonsummer pruned trees because of less shoot mortality and more fruit per tree.

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Liang Zheng, Qi Zhang, Kexin Zheng, Shumei Zhao, Pingzhi Wang, Jieyu Cheng, Xuesong Zhang, and Xiaowen Chen

greenhouse cover, light-diffusing cover scatters a certain fraction of the transmitted direct light into diffuse light, thus potentially improving the uniformity of spatial and temporal light distributions and increasing the radiation efficiency of the crops

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Cary A. Mitchell

will seedling or graft transplants produced under sole-source, narrow-spectrum LED lighting adapt to subsequent transplantation to the greenhouse or field, where transplants then will encounter broadband solar light? DISTRIBUTION OF SOLAR AND