Antitranspirant Treatments of Stock Plants do not alter Growth and Adventitious Rooting of Shoots of "Montaigne" Lilac and White Fringetree

Susan M. Switras-Meyer and Jeffrey H. Gillman

Department of Horticultural Science, University of Minnesota, St. Paul, MN 55108

Citation

Switras-Meyer, S. M. and J. H. Gillman. 2002. Antitranspirant treatments of stock plants do not alter growth and adventitious rooting of shoots of "Montaigne" lilac and white fringetree. Jour. Environ. Hort. 20(4): 240-244.

Abstract

Antitranspirants were evaluated for their effectiveness as a stock plant treatment to improve adventitious rooting of softwood cuttings of Syringa vulgaris L. 'Montaigne' (Montaigne lilac) and Chionanthus virginicus L. (white fringe tree). New shoots of S. vulgaris ‘Montaigne’ and C. virginicus were sprayed with one of two film-forming antitranspirants including Clear Spray (aqueous acrylic emulsion) and sodium silicate; or Atrazine, a herbicide that acts as a stomate-regulating antitranspirant. Shoot caliper of antitranspirant-treated lilacs increased more slowly than controls. Thirty days after treatment cuttings were taken from both taxa. All treatments resulted in 80 to 85% rooting of cuttings in lilac after 6 weeks, but cuttings from Clear Spray-treated plants rooted more quickly. Chionanthus virginicus cuttings treated with Clear Spray had significantly lower rooting (16%) than cuttings taken from Atrazine treated plants (50%). In a subsequent experiment, antitranspirant treatment had no significant effect on shoot length or caliper of 'Montaigne' lilac. Photosynthetic rate, transpiration rate, and location of cutting on the stock plant were all positively correlated with shoot length, shoot caliper, and cutting diameter. Shoot length and caliper and cutting diameter, however, were all negatively correlated with root number and root length. There were no significant treatment effects on rooting percentage, root number or root length.

Table 1. Percent increase in shoot lengths and calipers {[(final size - initial size)/initial size]´100}of C. virginicus (Expt. 1) and S. vulgaris 'Montaigne' lilacs (Expt. 2) 28 and 30 days after being treated with antitranspirants respectively. Significant differences within columns calculated using Duncan's multiple range test (P< 0.05; n=80 for C. virginicus, n=100 for S. vulgaris 'Montaigne').

		C. virginicus			S. vulgaris
Treatment	Shoot Length		Caliper	Shoot Length		Caliper
Control	11.3 a		18.9 a	10.2 a		43.9 a
Atrazine	10.9 a		17.3 a	12.1 a		28.9 b
Clear Spray	5.9 b		19.3 a	10.4 a		28.9 b
Silicon	9.7 a		13.8 a	12.2 a		16.1 c

Table 2. Percent of C. virginicus cuttings that rooted and root number and length of rooted cutting 6 weeks after cuttings from treated plants were placed into rooting cells. Significant differences within columns calculated using Duncan's multiple range test (P< 0.05; n=8 for % rooting, n=45 for root number and root length).

Treatment	% Rooted	Root number	Root length
Control	40.6 ab	7.8 a	103.2 a
Atrazine	50.0 a	7.1 a	75.0 a
Clear Spray	15.6 b	10.0 a	95.2 a
Silicon	34.3 ab	7.8 a	74.7 a

Table 3. Percent of S. vulgaris 'Montaigne' cuttings that rooted 3, 4, 5 and 6 weeks after cuttings from treated plants were placed into rooting cells, and root number and root length of cuttings that rooted 6 weeks after cuttings were placed into rooting cells. Significant differences within a column calculated using Duncan's multiple range test (P< 0.05; n=11 for % rooting, n=148 for root number and root length).

Treatment	Week 3 % Rooted	Week 4 % Rooted	Week 5 % Rooted	Week 6 % Rooted	Week 6 Root number	Week 6 Root length
Control	4.5 b	47.7 ab	70.5 a	84.1 a	10.7 a	43.6 a
Atrazine	6.8 b	43.2 b	72.7 a	81.8 a	12.8 ab	45.6 a
Clear Spray	29.5 a	72.7 a	81.8 a	79.5 a	16.2 b	56.2 b
Silicon	11.4 b	40.9 b	84.1 a	81.8 a	14.1 ab	51.4 ab

Table 4. Average shoot length and diameter of antitranspirant treated lilacs (Syringa vulgaris 'Montaigne') over time.
Numbers are means of five replicates ± standard deviation.
							Single Leaf Shield Application						Multiple Leaf Shield Applications						Control
	Atrazine
Day^z	Length (mm)			Diameter (mm)			Length (mm)			Diameter (mm)			Length (mm)			Diameter (mm)			Length (mm)			Diameter (mm)
0	19.8	±	1.1	2.9	±	0.3	19.3	±	1.7	2.9	±	0.4	20.4	±	1.7	3.1	±	0.2	20.6	±	2.7	3.0	±	0.7
3	24.5	±	1.7	3.1	±	0.3	23.2	±	2.3	3.1	±	0.4	25.4	±	1.5	3.4	±	0.2	25.5	±	4.0	3.2	±	0.7
7	29.1	±	3.8	3.3	±	0.3	28.1	±	3.9	3.2	±	0.4	32.7	±	2.9	3.5	±	0.2	30.5