We examined effects of single-layer glass and double-layer antifog polyethylene films on growth and flowering of stock (Matthiola incana L.) and snapdragon (Antirrhinum majalis L.) in a 3-year period. Stock produced more buds/spike with shorter but thicker stems under single-layer glass and under antifog 3-year polyethylene, and showed higher photosynthetic capacity (P c) under single-layer glass than under other covers regardless of light regimes. Similarly, growth and flowering of snapdragon were significantly better under single-layer glass than in polyethylene houses. A supplemental light of 60 μmol·m-2·s-1 accelerated flowering by 20 to 25 days, improved flower quality, and eliminated differences in plant growth and quality of snapdragon between covering treatments. The P c of stock was lower under all polyethylene covers than under single-layer glass. Among the three antifog polyethylene films, a slightly higher P c was measured for plants under antifog 3-year polyethylene. However, there was no difference among covering treatments in the net photosynthetic rate (P N) at low light level (canopy level). Supplemental lighting reduced P c of stock leaves, especially under single-layer glass, and diminished differences in P c among covering treatments. Dry mass was more influenced by larger leaf area caused by higher leaf temperature than by P N. Overall, antifog 3-year polyethylene was a good covering material when both plant quality and energy saving were considered.
B. Dansereau, Y. Zhang, S. Gagnon, and H.L. Xu
Y. Zhang, L. Gauthier, D. de Halleux, B. Dansereau, S. Yelle, and A. Gosselin
qA 3-year study was undertaken to quantify the effect of four greenhouse covering materials on energy consumption, microclimate, and the growth and production of cut flowers Matthiola incana (Stocks) and Antirrhinum majalis (Snapdragons) in the greenhouse. The four materials are single glass (GL), polyethylene (PE) + anti-fog 1-year polyethylene (AF1), polyethylene + antifog 3-year polyethylene (AF3), and polyethylene + anti-fog thermal polyethylene (AFT). The effect of thermal screen and supplementary lighting (60 μmol·m–2·s–1) also are discussed. This study indicated that AFT film is the most energy efficient material and AF3 film is the most transparent to photosynthetic active radiation (PAR). For stocks, good quality can be obtained in GL and AF3 in terms of spike length, stem diameter, as well as number of buds and flowers. The stocks in GL, however, always possess the highest photosynthetic capacity, regardless light treatment. For snapdragons, the growth and flowering in PE houses were significantly improved by supplementary lighting
Wook Oh, In Hye Cheon, Ki Sun Kim, and Erik S. Runkle
houstonianum L.), celosia ( Celosia argentea var. plumose L.), impatiens, geranium ( Pelargonium ×hortorum L.H. Bail.), French marigold, pansy, petunia, red salvia, snapdragon ( Antirrhinum majalis L.), stock ( Matthiola incana L.), vinca, and zinnia