The Use of Reflective Film and Ethephon to Improve Red Skin Color of Apples in the Mid-Atlantic Region of the United States

Abstract

<jats:p>Replicated studies were conducted from 1996 to 1999 to evaluate the effect of a metalized reflective film (RF) on red color development in several apple (<jats:italic>Malus</jats:italic> ×<jats:italic>domestica</jats:italic>) cultivars that often develop poor to marginal color in the mid-Atlantic growing region. Film was applied to the orchard floor in the middle between tree rows or under the tree beginning 5 to 7 weeks before the predicted maturity date. Light reflected into the canopy from the RF was measured and compared with a standard orchard sod, a killed sod or various polyethylene films. Fruit color was estimated visually and with a hand-held spectrophotometer. Fruit quality (firmness, soluble solids, starch index) was determined from a representative sample of fruit. RF increased the level of photosynthetic photon flux (<jats:italic>PPF</jats:italic>) reflected into the canopy resulting in darker, redder colored `Delicious', `Empire', and `Fuji' apples with a greater proportion of surface showing red color. RF increased canopy temperature and fruit surface temperature. A white polyethylene film increased reflected <jats:italic>PPF</jats:italic> and fruit color, but generally not to the extent of the metalized RF. Large [&gt;13 ft (4.0 m) height] well-pruned `Delicious' trees showed increased fruit color, especially when the RF was placed under the canopy, but `Empire' trees of similar size and a more dense canopy showed no effect. The effect of the RF was most pronounced in the lower portion [up to 8 ft (2.4 m) height] of the canopy. A high-density RF was as effective as a low-density RF and the high-density film was about 60% less expensive. A high-density RF may be a cost effective method to enhance red color on selected apple cultivars in the mid-Atlantic region. Comparisons between ethephon and the RF were variable: ethephon appeared to have more effect on color in `Empire' than the RF, but less effect than the RF on `Hardibrite Delicious'. Ethephon consistently advanced fruit maturity. Chemical name used: (2-chloroethyl)phosphonic acid (ethephon).</jats:p>

The Use of Plastic Films and Sprayable Reflective Particle Films to Increase Light Penetration in Apple Canopies and Improve Apple Color and Weight

“…Training systems (Hampson et al, 2004), growth regulators (Miller, 1988), plant nutrition (Williams and Billingsley, 1974), and reflective films (Layne et al, 2001(Layne et al, , 2002Miller and Greene, 2003) are techniques that improve fruit quality entirely or in part by improving light penetration into the tree canopy. Reflective films have been developed to reflect narrow bands of light (Kasperbauer, 1999) or the entire spectrum using white (Grout et al, 2004) or metallized films (Layne et al, 2001(Layne et al, , 2002Miller and Greene, 2003). Reflective films increase red color development in apple, primarily in the lower half of the canopy (Moreshet et al, 1975) and may alter date of fruit maturation (Miller and Greene, 2003).…”

“…Reflective films have been developed to reflect narrow bands of light (Kasperbauer, 1999) or the entire spectrum using white (Grout et al, 2004) or metallized films (Layne et al, 2001(Layne et al, , 2002Miller and Greene, 2003). Reflective films increase red color development in apple, primarily in the lower half of the canopy (Moreshet et al, 1975) and may alter date of fruit maturation (Miller and Greene, 2003). Layne et al (2001Layne et al ( , 2002 measured increased ultraviolet A radiation (UVa) (330-400 nm), photosynthetically active radiation (PAR) (400-700 nm), and near-infrared radiation (NIR) (700-1100 nm) reflection from a reflective film and a resulting increased air temperature within the canopy and found that the red light/far-red light ratio (R/FR) of the reflective film was similar to incoming radiation.…”

“…Colored netting, while reducing light, can also increase yield (Shahak et al, 2004). Despite the increased light levels in the canopy from reflective films, increased fruit size is infrequently documented according to Miller and Greene (2003); only Moreshet et al (1975) and Grout et al (2004) document an increase in apple yield and size. Green et al (1995) state that PAR interception by the canopy can be increased as much as 40% with reflective films.…”

“…Therefore, the lack of in-creased productivity suggests that light quality may be a factor in reflected light from these films. Miller and Greene (2003) demonstrated an economic benefit of reflective films for a high-density metallized silver polyethylene film in apple production resulting from improved color development. The use of a kaolin-based particle film material has inconsistently increased apple color (Glenn et al, 2001(Glenn et al, , 2003(Glenn et al, , 2005.…”

Juneberry Growth Is Affected by Weed Control Methods

“…Reduction in juneberry growth was attributed to the stress incited by the warm microclimate from the dark-colored, reflective landscape fabric. Miller and Greene (2003) reported that reflective films placed at orchard floors can increase plant canopy temperatures up to 19.8°F compared with plots without reflective film. St-Pierre and Tulloch (2002) reported greater juneberry growth when grown in black plastic compared with those grown in wood chips or without mulch, even though plants suffered from sun scald.…”