Effects Of Temperatures On Photosynthetic Characteristics Physiological Indexes Of Bletilla Striata

Bletilla striata is a kind of perennial herb which belongs to Bletilla Genus in Orchidaceae,has important medicinal and ornamental value.In addition,it has wide variety of applications in beauty cultureand industry field.Temperature is one of the most important factors that influence the growth,yield and quality of Bletilla striata.In this research,Bletilla Striata plants as materials were treated with different temperature in plant growth chambers.The photosynthetic physiological and biochemical characteristics were studied to explore the suitable temperature for the growth of Bletilla striata,which Provided heoretical basis and technical support for scientific planting of Bletilla Striata.One-year-old Bletilla Striata plants were treated by four different low temperatures of 22?,18?,14? and 10?and four different high temperatures of 30?,34?,38? and 42?.Each treatment was performed recovery training with the 26 ?.The measurement of photosynthesis and biochemical indexes was conducted at 0 d,7 d,14 d,21 d and 28 d of the temperature treatment,and 3 d,7 d of the recovery period.The results of the study are as follows:For the appearance,the leaf tip of Bletilla Striata began to yellow at 7 d in 10? treatment,and completely died at 28 d.At 14?,the tip of the leaf began to yellow at 7 d,and the plants were in a semi-lethal state at 28 d.There was no significant change of the plants during treatment and recovery at 18?and 22?.At 30?,the leaf of Bletilla Striata was no significant change.At 34?,the tip of the leaf turned yellow at 21 d.At 38?,the tip of the leaf was yellow at 14 d and the 1/2 leaf turned yellow at 28 d.At 42?,the plants died at 7 d.The results of study in photosynthetic characteristics of Bletilla Striata showed that in low-temperature environment,the PSII system of leaf was inhibited seriously under 10?and 14?treatment.The photosynthesis of Bletilla Striata was slightly inhibited under 18?.However,it was not affected under 22?.The PSII system was not inhibited under 30 ?.The photosynthesis of Bletilla Striata was slightly inhibited and the PSII system of leaf was inhibited under 34?,however,the damage was not to irreversible.The photosynthesis system of Bletilla Striata was severely inhibited and it was restored lightly under 38?.Under 42? treatment,the PSII system of leaf was inhibited seriously and irreversibly.The results of study in physiological indicators showed,in low temperatures,SS of leaf increased first then decreased under 10?.And,it increased continuously under 14?,18?and 22?.SP of leaf continued to increase at low temperature.Pro of leaf fell after rose under 10? and 14? environment,and it elevated continuously under 18?and 22?.In the environment of high temperatures,SS of leaf continued to rise under 30?,34?and 38? and it reduced rapidly under 42?.SP and Pro continued to rise in the environment of 30?and 34?,rose first and then fell under 38 °C,and rapidly decreased under 42?.Studies on enzyme activities found that the activities of SOD and POD rose first then decreased under 10?and 14?,however,it continuously increased under 18?and 22?,and significantly reduced after recovery treatment.The activities of CAT and APX continuously decreased under 10?and 14?,however,the activities of CAT and APX continuously increased under 18?and 22?,significantly reduced after recovery treatment.In high temperatures environment,the activity of SOD increased continuously in the environment of 30?,34?and 38?,and decreases rapidly in the environment of 42?.The activity of POD continued to rise in the environment of 30?,and it rose first then decreased in the environment of 34?and 38?,and it rapidly decreased in the environment of 42?.The activities of CAT and APX increased continuously in the environment of 30?,and increased then decreased at 34?,and continuously decreased in the environment of 38?and 42?.These findings suggested that when the Bletilla Striata long-term in the environment below 14?and above 38?,it will damage the plant morphology and photosynthesis,and break the balance of osmotic adjustment system and antioxidant system,causing irreversible damage for Bletilla striata eventually.The physiological metabolism of Bletilla striata will be caused reversible mild inhibition in the environment of 18? and 34?.Therefore,the suitable temperature range of Bletilla striata is between 22? and 30?.