Plant Height Control by Photoselective Filters: Current Status and Future Prospects

Abstract

<jats:p>The interest in using nonchemical alternatives for growth control of horticultural crops has recently increased due to public concerns for food safety and environmental pollution. Several research teams around the world are investigating alternative growth control measures, such as genetic manipulation, temperature, water and nutrient management, mechanical conditioning, and light quality manipulation. This review discusses the recent developments in light quality manipulation as a nonchemical alternative for greenhouse plant height control.</jats:p>

Light-Quality Manipulation by Horticulture Industry

“…Compared with common black nets of the same shading factor (in PAR), the red and yellow nets specifically stimulated vegetative growth rate and vigour, while the blue net caused dwarfing in Pittosporum variegatum, Aralia and Philodendron monstera, as well as in seasonal cut flowers (Lisianthus, Trachelium, sunflower and lupine; Figure 12.3). These effects are similar to effects reported for photoselective films and artificial illumination (Kasperbauer, 1971;Rajapakse et al, 1999;Kim et al, 2004). The grey net also enhanced stolon branching in leather-leaf fern and Ruscus.…”

“…Far-red light absorption capacity increased with increasing dye pigment concentration in the film, but increasing dye concentration reduced the transmission of photosynthetic light (van-Haeringen et al, 1998). Photoselective films produced with a low concentration of dye (corresponding to a 15% reduction in light transmission) did not cause a commercially significant reduction in stem elongation while photoselective films produced with a high concentration of dye (corresponding to a 45% reduction in light transmission) reduced stem elongation, but overall quality of plants was poor due to reduced photosynthetic light (Rajapakse et al, 1999). Far-red light filtering photoselective films developed for commercial testing reduced the transmission of photosynthetic light by 20-25% but were effective in reducing stem elongation in wide range of ornamental and vegetable transplants, without adversely affecting the overall quality of transplants (Table 12.2; Plate 12.1).…”

“…LIGHT AND PLANT DEVELOPMENT Photoselective plastic greenhouse films with far-red light absorbing dye pigments have been developed by greenhouse film manufacturers in Japan (Mitsui Chemicals Inc.) and the United Kingdom (BPI Agri) and tested on a wide range of crops, especially focusing on height control of bedding plants (vanHaeringen et al, 1998;Rajapakse et al, 1999;Runkle and Heins, 2003;Fletcher et al, 2005). Photoselective films, in general, reduced the transmission of both red (600-700 nm) and far-red (700-800 nm) light, but the reduction of far-red light is greater, therefore resulting in a higher R:FR of transmitted light (Figure 12.1).…”

Manipulation of light spectral quality disrupts host location and attachment by parasitic plants in the genus Cuscuta

“…; Rajapakse et al . ; Paul & Moore ; Lykas, Kittas & Katsoulas ). Large‐scale manipulation of spectral quality under field conditions to control dodder infestations will no doubt pose significant technical challenges.…”

“…Spectral manipulation techniques have previously been employed effectively for the control of other classes of pests and pathogens in greenhouses (Raviv & Antignus 2004;Nguyen et al 2009) and to control plant growth without the use of growth regulators (Decoteau et al 1988;Rajapakse et al 1999;Paul & Moore 2006;Lykas, Kittas & Katsoulas 2008). Large-scale manipulation of spectral quality under field conditions to control dodder infestations will no doubt pose significant technical challenges.…”