Ethrel sprays were applied to Concord grape vines on September 4, 11, 19, and 26, 1968 in concentrations varying from 10 to 2000 ppm. At daytime temperatures averaging 69.7°F Ethrel promoted the abscission of berries in six days or less at 250 ppm and higher. Daytime temperatures of 63°F or higher prior to normal harvesting appeared necessary to activate berry abscission in six days or less. Concentrations of 250 ppm and higher induced leaf yellowing and accelerated leaf senescence. Berries removed easier when shaken off at 77°F than at 62°F. Grapes receiving a foliar application of 250 ppm of Ethrel 14 days before harvest removed easier than those receiving 500 ppm Ethrel applied six days before harvest when both were shaken off the same day. Ethrel resulted in no differences in fruit soluble solids, titratable acidity, pH and color determinations. There was no response from dipping only clusters in Ethrel. A minus 11°F on December 30 caused serious bud damage on vines sprayed on September 4 at 2000 ppm, compared to non-sprayed vines.
6-Furfuxylamino purine (kinetin) at 0.1% plus indoleacetic acid (IAA) at 0.005 to 0.025% in lanolin, applied directly to the lateral buds at nodes on the basal portion of stems induced aerial crown formation with shoot growth.
Asparagus plants freed of 3 viruses were obtained by aseptic culture of shoot tips and apical meristems. More plantlets developed from shoot tip cultures than from apicalmeristem cultures, but a much larger proportion of the meristem cultures were virus free. Consequently, the number of virus-free plants obtained by these 2 methods were approximately equal. The ease of excising and culturing shoot tips makes this the preferred method. The aseptic stock plants obtained are being used as the source of propagants for mass production of virus-free asparagus plants.
More rooted Asparagus officinalis L. plantlets were obtained in vitro from stem segments with 3 or more branch-shoots than from those with 1 or 2 branch-shoots; those without branch-shoots produced the fewest plantlets.
One-bud segments from moderately vigorous shoots of aseptically grown Asparagus officinalis L. stock plants were cultured on modified Murashige and Skoog’s medium (MMS) containing 0.1 ppm of α-naphthaleneacetic acid (NAA) and 6-furfurylamino purine (kinetin). Only 35% of the cultures developed into rooted plantlets. A high percentage of nonrooted plantlets were induced to root by reculturing on fresh MMS medium containing 0.1 ppm NAA. More plantlets rooted if they were older than 4 weeks when recultured on the fresh medium.
Survival of Asparagus officinalis L. transplants in soil was significantly improved with a minimum of labor when they were first transplanted into the Jiffy 7 peat pots from aseptic culture and grown under intermittent mist for 5 to 8 days.
Asparagus is generally propagated by seed and occasionally by crown division. Crowns are usually formed underground at the base of stem (1, 2, 3, 4). To our knowledge, the formation of crowns at above-ground nodes and plant development therefrom has never been reported. Occurrence of such crowns opens the way to a rapid means of vegetative propagation. Here we describe the morphology of aerial crown formation and subsequent development of these crowns into apparently normal plants.
A modified procedure was developed for vegetatively increasing normal diploid Asparagus officinalis L. This is accomplished by culturing stock plants from unrooted lateral buds from spears, and by rooting buds from basal portions of shoots of stock plants. Murashige and Skoog's inorganic medium with added growth substances was used.