Gibberellin Induces Shoot Growth and Flowering in Nonprecooled Derooted Bulbs of Tulip (Tulipa gesneriana L.)

The present study was conducted, using simple equations, to analyze the accumulation rate of silica [ARSi], that or minerals [ARM] and silica contenl changes with growth of Rhodes grass [Rg] and Greenleaf desmodium [Gd]. The following two equations were suggested for analyses: ARSi = 1/W * d(Si)/dt = (1/W * dM/dt) * d(Si)/dM, (A) Changes in silica content = 1/1000 * ((Si)_2/W_2 * (Si)_1/W_1) = (1 - W_1/W_2) * [1/1000 * (ARSi/RGR - (Si)_1/W_1)]. (B) where W=forage dry weight (g/m^2), Si=amount of silica in the forage (mg/m^2), M=amount of minerals in the forage (mg/m^2), (1/W) * (d(Si)/dt) = ARSi, (1/W) * (dM/dt) = ARM, (d(Si)/dM) = accumulation of silica per unit accumulation of M[ASiAM], RGR = mean relative growth rate [RGR] of forages over the interval t_1 to t_2, ARSi = mean ARSi over the interval t_1 to t_2 (1 - W_1/W_2) = forage growth index [FG index], [ARSi/RGR- (Si)_1/W_1}/1000 = an index for forage growth dependent silica accumulation [FGDSiA index]. Analyses using equation (A) suggested that Rg showed a higher selection of silica in the accumulation of minerals, when compared with Gd. Analyses using equation (B) suggested that Rg showed less active silica accumulation than forage growth, in contrast to more active silica accumulation than forage growth in Gd. It was suggested that the present methods accounted analytically for the accumulation characteristics of silica and its content changes with growth of forages

Inhibitory Effect of Abscisic Acid on Shoot Growth and Flowering Induced by Gibberellic Acid in Nonprecooled Derooted Bulbs of Tulip (Tulipa gesneriana L.)

Effect of gibberellic acid (GA_3) at a concentration of 200mgl^<-1>, abscisic acid (ABA) at a concentration of 20 mgl^<-1> and their mixture on shoot growth and flowering in nonprecooled derooted tulip bulbs cv, Apeldoorn was investigated. As it was found previously GA_3 induced shoot growth and flowering in nonprecooled derooted bulbs of tulip. The present studies showed that the simullaneous application of GA_3 with ABA totally inhibited shoot growth and flowering induced by the gibberellin in nonprecooled derooted tulip bulbs, These results suggest that hormonal balance, gibberellins-abscisic acid, is the important factor in control of dormancy and dormancy release of tulip bulbs, causing shoot growth and flowering