Effect Of Short-day Treatment On The Pinus Tabulaeformis Carr. Container Seedling Quality

Pinus tabulaeformis Carr.is a native tree species in China and one of the most important afforestation species in North China.It is important to improve the ecological environment and to accelerate afforestation in the difficulty site condition in China.At present,the afforestation of Pinus tabulaeformis in northern China is becoming more and more difficult,to improve the nursery and afforestation techniques of Pinus tabulaeformis container seedlings is an effective way to ensure the survival rate of afforestation.Short-day treatment has proved to be an effective way to regulate seedling quality and stress resistance,which is widely applied on Picea abies,Pinus sylvestris and other conifer species in Northern Europe and Northern America.But little attention is received in China.Therefore,It is necessary to study the short-day treatment on Pinus tabulaeformis container seedling quality and its stress resistance mechanism,and to improve nursery and afforestation techniques of this species.In this study,Pinus tabulaeformis container seedlings(1-0)were used as the research object to find short-day treatment model suitable for seedlings and determine basic metabolism and stress resistance response to short-day treatment.The main contents of the study were as follows:evaluating how short-day treatment affected the seedling growth and 5-year outplanting performance;the effects of two short-day treatment models on the root morphological development,ABA and non-structural carbohydrate contents,lignification and drought resistance of seedlings;the molecular mechanism of short-day treatment and regulation of seedling quality and stress resistance with a proteomic analysis using two-dimensional electrophoresis(2-DE)in combination with MALDI-TOF/TOF MS analysis,which would help with understanding the short-day treatment theory and providing theoretical basis for applying the short-day treatment on seedlings.Our research shows that(1)The interactive effects of starting time and day length on the survival rate of Pinus tabulaeformis container seedlings(1-0)was significant.The fifth year survival rate of outplanting Pinus tabulaeformis seedling short-day treatment started on July 24 with 10h day length was higher than control by 50.2%.(2)Short-day treatment increased carbohydrates in roots,promoted fine root growth of root diameter 0.0<D1?0.2 mm,0.2<D2?0.5 mm and optimized root architecture of Pinus tabulaeformis container seedlings.The Fine root length of root diameter less than or equal to 0.5 mm of seedling short-day treatment started on July 24 with 10 h day length was higher than control by 20.8%.(3)Short-day treatment promoted seedling ABA synthesis and accumulation,the ABA contents of SD2-10h-treated seedlings was higher than control by 62.8%,which adjusted the distribution of carbohydrates and affected the growth of seedling roots and the lignification of aboveground parts.(4)Short-day treatment stimulated seedling lignin synthesis related enzyme activity and promoted seedling lignin synthesis.The stem and leaf lignin contents of SD2-10h-treated seedling were higher than control by 10.2%and 16.1%respectively,which was beneficial to improve the degree of lignification of seedling aboveground parts.(5)Short-day treatment is beneficial to improve the drought resistance of seedlings.(6)We obtained five proteins expressed differentially(p<0.05)induced by short-day treatment.They were oxygen-evolving enhancer protein 1(OEE1),glyceraldehyde-3-phosphate dehydrogenase(GAPDH),phosphoglycerate kinase 1(PGK1),elongation factor-Tu(EF-Tu)and ribulose bisphosphate carboxylase/oxygenase activase(RCA).They are mainly involved in plant photosynthetic metabolism,sugar metabolism and stress defense.