The method of conventional exhaustion and improved exhaustion was carried out to study the kinetics characteristics of nitrogen absorption in root of Malus baccata Borkh. seedlings in cool and cold conditions. The characteristics of nitrogen absorption kinetics were affected by cool and cold condition. In normal temperature(25 ℃)the affinity of NO3- was greater than that of NH4+ which indicated that root had the priority to absorb NO3-. But in cool and cold condition(10 ℃)the affinity of NH4+ was greater than that of NO3-,and in this moment the root had the priority to absorb NH4+. The M. baccata Borkh. seedlings’ absorption was decreased in cool and cold condition and it was indicated that the maximum absorption velocity,nutrient inflow velocity and affinity of NO3- and NH4+ were decreased in cool and cold condition. The influence of cool and cold condition in absorbing NO3- was greater than absorbing NH4+.
In order to further explore the molecular regulation mechanism of PG during‘Fuping Jianshi’persimmon(Diospyros kaki L.)postharvest softening with different treatments, and to improve the persimmon ripening and softening process,the responses of DkPG1 gene and PG activities in persimmon fruit to propylene and 1-MCP at the room temperature were investigated by real-time quantitative PCR(RT-qPCR)approach and DNS method. The results showed that accompanying with fruit ripening,the expressions of DkPG1 gene in fruits with different treatments had the same trend on the transcript level that it first steadily increased to the maximum and then decreased. After 4 days of propylene treatment,the expression of DkPG1 gene increased to the maximum which was dramatically higher than the control,and it appeared 12 days ahead of the control;The expression peak of DkPG1 gene in fruits treated with 1-MCP appeared at 28 days,12 days later than the control,which was significantly lower than the control. The activity of PG in fruits treated with propylene rapidly increased, and the activity peak appeared at the same day DkPG1 gene expression peak appeared;1-MCP treatment made the activity peak of PG decrease and appear 4 days earlier than its DkPG1 expression peak. Besides,the results about the analyze of ethylene release rate and pectin component showed the expressions of DkPG1 gene were regulated by ethylene,and then affected the pectin component metabolism.
‘Chenguang’is a new tetraploidy Chinese jujube(Ziziphus jujuba Mill.) cultivar obtained from‘Linyilizao’which was induced by colchicine. Its fruit is big,nearly round,with the average fruit weight of 39.6 g and edible ratio of 98.5%. The fruit tastes sweet,crisp and juicy,with thin pericarp. ‘Chenguang’is characterized by high yield,early-fruiting. It is an excellent mid-rippening table cultivar which is suitable to be cultivated in mid-south part of Hebei Province.