To investigate the photosynthesis and growth of Cymbidium ‘Red Fire’ grown under different nitrogen fertilization and night-interruption (NI) illumination, we exposed plants to 9-h short days (SDs), SDs + 3 - 7 μmol·m-2·s-1 NI (low-light intensity of NI, LNI), or SDs + 120 μmol·m-2·s-1 NI (high-light intensity of NI, HNI) illumination with nitrogen supplemented at 0, 100, 200, or 400 mg·L-1. Cymbidium photosynthesized under 3 – 7 μmol·m-2·s-1 NI regardless of nitrogen treatment, promoting growth. HNI treatments and nitrogen supplements at 100 mg·L-1 increased the leaf chlorophyll concentration. LNI increased net CO2 assimilation (An), transpiration, and stomatal conductance. HNI without supplemental nitrogen reduced midday An. However, HNI with supplemental nitrogen increased midday An. Supplemental nitrogen should be provided to Cymbidium when high-irradiance NI is used to promote growth.

Flowering responses under night interruption (NI) condition were determined in Doritaenopsis ‘Fuller’s Sunset ’, ‘Green Beer’, ‘Little Gem Stripes’, and ‘Queen Beer’ during their reproductive stages. Plants were grown under 10/14 h ambient light/dark (control), 10 h ambient light with night interruption (22 : 00-02 : 00 HR) at low light intensity of 3-7 μmol • m−2 • s−1 (LNI) and 10 h ambient light with NI at high light intensity of 120 μmol • m−2 • s−1 (HNI) conditions after flower spike emergence. Time to visible bud and flowering decreased more in the plants grown under HNI than those grown under LNI or control conditions. The number of buds or flowers increased in the plants grown under both LNI and HNI conditions compared to those grown under control condition for all cultivars. The tallest plants at flowering were in the HNI group in ‘Queen Beer’, ‘Green Beer’, and ‘Fuller’s Sunset’, however, the plant height was not significantly different among the treatments in ‘Little Gem Stripes’. NI with low light intensity or high light intensity can be used effectively to promote flower opening, but not with low light intensity at flower development stage. To obtain early flowering with high quality plants using NI treatment during their reproductive stage, high light intensity strategies could be suggested in Doritaenopsis cultivation.

Seed dormancy is an important adaptive mechanism to protect seeds under the unfavorable environments. Unlike to wild type species, the seed dormancy trait of cultivated crops has been weakened by breeding programs during the domestication period. Weak seed dormancy often causes preharvest sprouting (PHS) problem in many cereal crops that result in significant economic loss. The seed dormancy is a quantitative trait loci (QTL) controlled by multiple genetic and environmental factors. So far, many QTLs for seed dormancy have been identified from rice and wheat as well as in the model plant Arabidopsis. Unveiling of QTL genes and complex mechanisms underlying seed dormancy is accelerated by the rapid progress of crop genomics. In the present study, we reviewed current status of research progress on the seed dormancy QTLs and correlated genes in Arabidopsis and cereal crops.