Studies On The Characteristics Of The Growth And Development Under Photoperiod And The Cold Resistance Of Dendrobium Nobile

Dendrobium nobile (Nobile-type Dendrobium) belongs to Dendrobium orchid species,mainly for flower cultivation.It is another kind of new flowers,following Cymbidium and Phalaenopsis Orchids. The results are as follows:①Three variety’s photoperiod test results indicated:Compares with the SD, the Nobile-type Dendrobium under the long day develops lager number of leaves and pitch, with the longer and thicker pseudo bulbs. Obviously the LD promotes vegetative growth. The difference between stem lengths and stem thick under the two kinds of photoperiod increases along with the cultivation time’s extension. It is the 20th week that the difference of three variety’s stem length under the two photoperiods becomes obviously, while the stem thick difference shows obvious difference in 22nd week. Three varieties majority sprout 1 scale bud, minority sprouts 2,while very few has 3 scale buds. It is only the G1 under SD which has 3 scale buds, while others have not more than 3.②Photoperiod test results indicated: G1 can blossom, which’s flowering process could be divided into six phases:Infancy phase, elongating phase, squaring phase, color phase, opening phase and fade phase. Flowering time under the SD advanced the time of 25.8 days than the LD. With what Damann (1995) had ever referred to whether the non-induction of flowering is 2 times of induction flowering to judge. Plants under the LD flowering (242.5d) does not meet 2 times of the SD flowering (216.7d). It can be judged as facultative short-day plants. Under the SD condition G1’s lateral bud germination rate is 57.5%.the rate of flower buds is 21.4%, the high bud is 36.1%. There’s no flower bud and high bud on one plant under the SD. Plants under the LD had lower lateral germination rate, flowering rate and a high bud rate. It’s easier for the SD to induce flower buds than the LD.③The test results of G3 Under the two photoperiods treated with Plant growth regulator indicated: There’s neither blooming nor high bud developing under the treatment of 20mg/L GA3 nor Water. The growth regulators of 6-BA,6-BA+GA3 improved the floral bud differentiation of Nobile-type dendrobium. Flower buds under SD were significantly lower than LD. Bud rate decreased with the concentration of GA3 increased. The SD promoted the developing of bud scales. Plants under the SD treated with 6-BA (400 mg/L) + GA3 (50mg/L) developed 3.5 bud scales. While plants under the LD treated with GA3 (20mg/L) developed 1.3 bud scales. ④here were three varieties of Nobile-type Dendrobium in this study. The soluble sugar concentration, MDA content、chlorophyll content and SOD activity、CAT activity under low temperature stresses and recovery(day/night 22℃/15℃) including A treatment (12℃/5℃), B treatment (15℃/8℃), C treatment 18℃/11℃),Based on these physiological indicators. A comparison to resistance of the Nobile-type Dendrobium cold was carries on.