Dikegulac-Sodium Sprays Stimulate Shoot Emergence in Asparagus Under Lathhouse Conditions

Abstract

One-year-old greenhouse-grown 'Mary Washington', 'Emerald', 'UC 157 F,', and 'UC 157 F,' asparagus (Asparagus officinalis L.) seedlings were sprayed on 23 Sept. 1988 with dikegulac concentrations ranging from O to 750 mg·liter -1 in 150-mg·liter -1 increments. No significant shoot emergence occurred before frost killed the ferns in December. With increasing temperature in Jan. and Feb. 1989, dikegulac promoted shoot emergence in all cultivars, except 'Mary Washington'. At 600 mg·liter -1 , dikegulac had increased shoot emergence in 'Emerald', 'UC 157 F,', and 'UC 157 F 2 ' by 310%, 161%, and 305%, respectively, over the control on 2 Feb. After frosts killed the first shoots, all cultivars responded to treatment as temperature increased. Dikegulac did not affect the height and dry weight of 'Mary Washington' ferns, but it reduced the height of 'Emerald' without affecting its dry weight. Both height and dry weight of 'UC 157 F 1 ' and 'UC 157 F 2 ' were reduced by the chemical. There was a significant effect of cultivar on shoot production regardless of treatment, but no significant cultivar × dikegulac interaction on shoot emergence. However, there were significant effects of cultivar and cultivar × dikegulac interaction on height and dry weight of the ferns. After the ferns had been cut off on 9 Aug. 1989, only 'UC 157 F 1 ' and 'UC 157 F 2 ' showed increased shoot emergence. A second treatment of the plants with the chemical on 23 Sept. 1989 resulted in no significant increase in shoot emergence before or after freezing temperatures killed the ferns. Chemical name used: 2,3:4,6bis-0-(l-methyl ethylidene)-a-L-xylo-2 -hexulofuranosonic acid (dikegulac).