Study Of The Connection Between Low Temperature And The Early-flowering Tobacco At Seedling Stage

Tobacco is harvested maily for leaves which is closely related to the yield and economic benefits.The early-flowering tobacco is a big threat to the safety of tobacco production.Tobacco is susceptible to low temperature at the seedling stage,which leads to early flowering.In the growing process,there are many other factors leading tobacco from vegetative growth to reproductive growth,early flowering before the expected number of leaves reaches.This study selects the early flowering variety of NC82 and hardly early flowering variety of K326,using different temperature in different seedling age,determining the growth index,the number of leaves in the flowering and the changes in physiological and biochemical index when temperature gets low,studying how the low temperature at the seedling stage induces early flowering of tobacco.1.The effects of different temperature treatments on tobacco seedling and growthAlong with the leaf age increasing,the resistance of low-temperature-resistant variety is gradually increasing.When the number of leaves comes to 8,it's sensitivity to low temperature gets poor,but the early-flowering variety keep sensitive to low temperature.At 6 leaf age,the height of plants under treatment shows a very significant difference from which in normal temperature,the time can be chosen to do the low temperature treatment.At the low temperature of 8?,even the well resistant seedlings under a certain age can not resist,getting into stagnation.At the temperature of 14?,the seedlings of the low resistant variety is lower in height than which in other temperature.The significant difference recedes while the leaf age increases.14? is the appropriate temperature to do the low temperature treatment.The low temperature treatment in seedling stage can promote the anaphasis growth of tobacco plants in the field,but significantly inhibit the previous growth.2.The effect of different treatments on the number of the leavesFor NC82,at the temperature of 14?,the number of leaves decreases while the leaf age at the treatment time increases.The maximum reduction appears at 8 leaf age.At the temperature of 20?,the effect of leaf age increasing on the number of leaves is gradually decreasing.For K326,the variety of plants is obviously effected by temperature at 4 leaf age,the leaf number of 14?-proccessed plants shows significant difference from which in normal temperatue,less than two at least.With the leaf ageincreasing,the effect decreases obviously.It can be inferred that the low temperature can not induce early flowering of K326 at 6-8 leaf age.On the whole,at the temperature of 14?,NC82 and K326 at each leaf age is obviously effected by temperature.All the processed plants of NC82 are effected by temperature and mostly sensitive to low temperature at 6 leaf age while it shows none effection on the number of leaves in the flowering of K326.The research finds that 14? for 3 days will induce early flowering of the low resistant variety of tobacco.3.The effects of low temperature treatment on physiological and biochemical index of tobacco seedlingsWith the prolongation of cryopreservation time,the activity of related enzymes between different cultivars was more obvious difference after 3 days(72h),and the earlier the difference was the earlier.The results showed that the activity of SOD increased first and then increased with the prolongation of the duration of hypothermia,and the activity of SOD increased with the increase of the number of leaves.The results showed that the change of SOD activity was at the beginning of the 24 th day,and the resistance of the cultivars was decreased at the beginning of the24 th day,and the resistance was still declining at the beginning of the first day.At the48 th hour,The change mechanism of POD was similar to that of SOD,but it was more than that of SOD,and began to appear at the 48 th day.The resistant cultivars were the first to start with the non-resistant cultivars.The activity of PRO was higher than that of non-resistant cultivars after 72 h,and the content of PRO was the same as that under the influence of low temperature.The content of PRO was higher than that of leaf In addition,the content of non-resistant cultivars was always high at the same time,and the content of non-resistant cultivars was higher than that of non-resistant varieties at 8th day.The resistance of MDA to the growth of the non-resistant cultivars was increased.The final product of MDA as the cell membrane was increased first and then decreased with the increase of time,and increased with the increase of leaf age.,Generally higher than non-resistant varieties resistant varieties and increase appeared earlier and scope is huge.Overall,regulation of intracellular enzyme activity is a form of various types of dynamic fluctuation adjustment mechanism.When the low temperature resistant cultivars were under low temperature stress,the internal regulation mechanism was slow and ineffective,and the duration of the overall regulation was longer,and the response of the low temperature early flower varieties to the low temperature stress was the most timely and sensitive.there are certain differences in the relationship between low-temperature resistance.The chlorophyll content increased with the growth period of tobacco,and the dynamic regulation mechanism of chlorophyll content increased with the growth of 4 leaf age,and the variation range of cultivars was lower than that of non-resistant cultivars.The results showed that the content of the resistant cultivars decreased first and then decreased with the increase of the time,and the fluctuation of the 8-leaf was lower than that of the non-resistant varieties.inconsistent.The cell membrane permeability showed a complex and varied trend at each leaf age.The cell membrane permeability increased first and then decreased at 4 leaves,and then increased and then decreased after 6leaves decreased first and then decreased in the waveform rising trend,with the growth of the cell membrane Age of convergence of low-temperature resistance,its permeability discrepancies need low temperature stress and more time.In general,when the tobacco was under low temperature stress,it maintained the dynamic balance of the cells through the internal regulation mechanism,the resistance varieties were slow,the regulation efficiency was low,the non-resistant varieties were timely and efficient,the adjustment range was huge,at least three days a volatility adjustment that,in order to make appropriate cell membrane permeability to return to the level of cell growth,under 6 leaf stage continuous process three days there will be differences in trends.