Studies On The Removal Of Toona Sinensis Dormancy And Its Mechanism

In a design of square,regressive and orthogonal rotation with five factors,a field trial was conducted using Toona sinensis.This sdudy was undertaken to investigate the effects of gibberellic acid(GA3), 6-benzy laminopurine(BA), thiourea C.P.( (NH2) 2CS), Zinc Sulphate(ZnSO4), sa!tpeter(KNO3) for stratification on the dormancy-breaking of Toona sinensis,and to explore a more effective dormancy-breaking method and its mechanism.Results of the study are summerized as follows:(1)Effects of 6-BA, GA3, (NH2)2CS, ZnSO4and KNO3The relationship between days of early-spouting (Y) and factors including 6-BA(X,), GA3(X2), (NH2) 2CS (X3) , ZnSO4(X4) and KNO3(X5) is described with the equation, Y=6.421 + 0.688X, + 0.771X2 + 0.813X3- 0.854X4 + 0.647XJ -0.969X,X2+ 1.156X2X3+0.906X2X5- 1.094X3X4- 1.094X3X5. ZnSO4, (NH2)2CS and GA3 are chief factors, which play main importance for dormancy-breaking. The interactions between thiourea C.P. and ZnSO4,KNO3 and GA3 are significant.(2) The effective method for breaking buds dormancy.Toona sinensis buds dormancy could be broken by combined 6-BA (140mg / L) + GA3 (140mg/L) +(NH2)2CS (0.8%) +ZnSO4 (1%) +KNO3 (4%) and 6-BA (20mg/L) +GA3 (180mg/L) +(NH2)2CS (1%) +ZnSO4 (0.5%) + KNO3 (2 % ), which leads to quality and output improved.(3)Changes of carbohydrate and hormone contents during dormancy-breaking.During removal of Toona sinensis dormancy, starch content decreases,meanwhile soluble sugar content increases significant. Both GA1/3 and iPA content increased before decreasing, while ABA content decreased before increasing. Dormancy-breaking of Toona sinensis is controlled hormones balance, and carbohydrate content is varied.