Study On The Seed Characteristics And Germination Physiology Of Tutcheria Kweichowensis Chang Et Y.K.Li.

Tutcheria kweichowensis Chang et Y.K.Li is an evergreen tree with aesthetic appeal and excellent materials.Its fruit is rich in protein,fat,tea polyphenols,vitamin E（VE）,and vitamin C（VC）;thus,it has great exploitation and utilization values.However,because of its low natural reproduction rate,limited distribution,and narrow natural distribution area（the population patch is about 100 m²–30,000 m²）,it has become a rare and endangered plant with the ecological characteristics of a meta population.Under natural conditions,the seed rate of T.kweichowensis was very low;the seeds have a deep dormancy and are difficult to germinate,and it was rare to update seedlings under the forest.In the different population patches,the proportion of≤5 year old seedlings was less than 20%,the wild population was seriously declining,and the population dispersion was difficult.In this paper,we studied the biological characteristics of the seed of T.kweichowensis,as well as its inhibitor activity;experimented with dormancy-breaking technology;and determined the most suitable seed germination temperature,humidity,and illumination through a controlled study.We analyzed the inhibitor activity of the T.kweichowensis seed,found the most effective method of dormancy-breaking,revealed the characteristics of the seed and its basic physiological features of germination,determined the most appropriate conditions for seed germination and seedling cultivation,and its application technology.The study produced the following research results,which could provide a scientific basis for the effective protection and rational utilization of T.kweichowensis:（1）The seed of Tutcheria kweichowensis is kidney-shaped,black-brown or dark brown;the seed-case is hard,smooth,and dense,belonging to the typical hard seed group.The endosperm was rich in oil,the water absorption was≤15.62%,and the natural germination rate was≤27.11%.The seed 1,000-grain weight,viability,moisture content,and hard seed rate were 0.92 kg,66.17%,11.75%,and 89.17%,respectively.The contents of soluble sugar,soluble protein,starch,and fat in the seeds were 20.84%,11.19%,7.96%,and 50.27%,respectively.（2）The seed extracts from T.kweichowensis,extracted using different treatments,were used to soak Brassica campestris seeds,and the effects of the different extracts on the germination of B.campestris seeds were determined.The results showed that the T.kweichowensis seed contained germination inhibitory substances.Its biological activity was closely related to the extraction solvent,temperature,concentration,and site.The activity of the inhibitory substance in alcoholic solvent extracts was greater than that in aqueous solvent extracts.The inhibitory substance activity in the seed coat was significantly greater than that in the endosperm.All the different treatments of T.kweichowensis seed extracts had significant inhibitory effects on the seed germination and main root and seedling growth of B.campestris.The activity of the inhibitory substances increased with both the extraction concentration and temperature.（3）Under suitable environmental conditions,it is seed dormancy that stops seeds from germinating,which is mainly caused by the germination inhibitory substances,and the sources of the inhibitory substances are mainly endogenous,such as organic acids,phenols,aldehydes,and unsaturated lactones in plant seeds.Organic acids have a positive inhibitory effect on seed germination,which have great influence on the physiological metabolism during seed germination,and are more common in seed coats and endosperms.Using a systematic separation method,we obtained the extracts of each organic phase from the T.kweichowensis seed coat and endosperm using petroleum ether,ethyl ether,ethyl acetate,and methanol as the extraction solvents.After decompression and concentration,the gas chromatography–mass spectrometry（GC-MS）analysis and identification showed that six kinds of organic compounds with higher relative contents were found,which were organic acids,olefins,phenols,esters,alcohols,and aldehyde organic compounds,respectively.The relative content of organic acids was more than 80%,accounting for absolute superiority.It is the main inhibitory substance in T.kweichowensis seeds.There are five types and 10 kinds of organic compounds common in the seed coat and endosperm extract of T.kweichowensis,including five organic acids:oleic acid,linoleic acid,hexadecanoic acid,octadecanoic acid,acetic acid,and 2-methyl butyric acid;squalene;phenol;methyl oleate;and5-（hydroxymethyl）furfural.There are 10 kinds of unique organic compounds in the seed coat,which are acetic acid,2-methyl crotonic acid,2-hydroxy-γ-butyrolactone,glycerol monoacetate,methyl linoleate,diacetin,acetol,furfuralcohol,1,3-butanediol,furfural,and glycolaldehyde;the specific organic compound was only 1,2,3-propanetriol in endosperm.（4）We tried breaking the dormancy of T.kweichowensis seeds by different soaking methods,including soaking in water at an initial temperature of 100℃ for 24 h,15%NaOH solution for 20 min,concentrated sulfuric acid for 15 min,6%H₂O₂ solution for 12 h,300mg/l GA₃ solution for 24 h,and 8%KH₂PO₃ for 8 h.These methods could significantly improve the germination rate of T.kweichowensis seeds;the seed germination rates were64%,60.67%,56%,49.33%,48%,and 47.33%,respectively.The seed coat was softened and the wax and oil of the seed coat were removed by the hot water soaking treatment,the inhibitory substances were also leached out,which increased the permeability of the seed coat and reduced the inhibitory substances,and the germination of the seeds was promoted;acid and alkali treatments corroded the seed coat and dissolved the chemical substances in it,which thinned and enhanced its permeability,reducing the hindrance of seed coat inhibitors to seed germination;the seeds more readily absorbed water and oxygen,thus the seed germination rate was improved.（5）In order to explore the suitable temperature and light conditions for T.kweichowensis seed germination,we carried out a regulation experiment on seed germination temperature and illumination.The results showed that in the incubator,the seeds began sprouting on the 10th day at 25℃,and the radicles and germs began to grow on the15th day;the seeds began sprouting on the 20th day at 20℃;25th day at 30℃,and 40th day at 15℃.The illumination had no obvious effect on the seed germination.The results determining the participation of enzyme activity in the physiological activities of T.kweichowensis germination showed that:the activity of protease,amylase,and acid phosphatase in T.kweichowensis seeds all showed the strongest activity at different germination stages at 25℃.The duration of illumination had no significant effect on the changes in nutrient contents and enzyme activity during the germination of the T.kweichowensis seed.It showed that T.kweichowensis seeds can germinate at a temperature range of 15℃–30℃,while the optimum temperature is around 25℃.（6）The germination of T.kweichowensis seeds is sensitive to temperature,and the restriction of ambient temperature was the main reason for germination inhibition in T.kweichowensisseeds.Throughstudyingthebiologicalcharacteristicsand dormancy-breaking techniques,it was concluded that the seeds should be kept at about 25℃,and a relative humidity of 80%–85%before sowing.After the wet sand layer was accumulated for 40 days,removed and soaked in hot water at an initial temperature of 100℃ for 24 h,then soaked in 15%NaOH solution for 20 min.