-type buds. Several studies have reported the role of plant hormones in flower bud differentiation in apple, but hormone regulating studies of apple flower buds and leaf buds remain limited. Zhou et al. (1988) studied the changes in endogenous hormone
Jinxin Wang, Tao Luo, He Zhang, Jianzhu Shao, Jianying Peng, and Jianshe Sun
John E. Preece and Ellen B. Wollbrink
Euphorbia Lathyris L. was readily propagated by stem cuttings in coarse sand or a 1:1 mix of perlite-vermiculite. Leaf bud cuttings did not root as well as stem cuttings, but rooting was promoted by indolebutyric acid (IBA), butanedioic acid mono-(2,2-dimethylhydrazide) (daminozide), and (2-chloroethyl)phosphonic acid (ethephon).
Jeanne M. Grout and Paul E. Read
The propagation method and vegetative condition of ‘Northblue’ blueberry (Vaccinium corymbosum L.) stock plants influenced microshoot production in vitro and root formation on leaf-bud cuttings. In tissue culture (TC), explants from TC-derived stock plants produced longer shoots than explants from leaf-bud, standard- (ST-) derived stock on either Zimmerman’s (Zimm) medium at pH 4.8, Lloyd and McCown’s woody plant medium (WPM) at pH 4.8 or pH 5.2. Microshoots from explants of TC-stock plants also rooted more readily. Microshoot rootability decreased after 18 weeks on medium containing 68.6 μmol (12 mg/liter) 2iP. Microshoot production and rootability increased after 3 additional weeks on Zimm medium without 2iP present. Leaf-bud cuttings of ‘Northblue’ TC-stock plants treated with 5% and 10% concentrations of a commercial rooting compound (Dip-n-Grow) had a slightly higher rooting percentage and root rating than nontreated cuttings from ST-stock plants. However, cuttings from ST-stock plants of the same age showed larger increases in root formation and percentage of rooting in response to the same rooting compound treatments. Leaf-bud cuttings from vegetative TC-stock plants that developed shoots had more basal branches than those from floral ST-stock plants. Branch elongation was greatest and basal branches fewest on cuttings from floral ST stock plants. Successful propagation with cuttings and in vitro explants may be related to the condition of the stock plants, which have been altered by their own propagation methods and the plant growth regulators applied. Chemical names used: 1H-indole-3-acetic acid (IAA); 1H-indole-3-butanoic acid (IBA); 1-naphthaleneacetic acid (NAA); N-(3-methyl-2-butenyl)-2H-purin-6-amine (2iP).
Jeanne M. Grout, Paul E. Read, and David K. Wildung
‘Northblue’ blueberry (Vaccinium corymbosum L.) plants propagated by tissue culture (TC) have a branching pattern and growth rate different from plants propagated by leaf-bud cuttings. Two to 3 times more basal branches were formed on tissue culture-derived plants by the time they were 27 to 34 weeks old. These basal branches were maintained on older plants in the field, where lateral branching was also twice as high. The growth rate of the young TC-derived plants was 3 times the rate of young leaf-bud, cutting-propagated (ST) plants. However, lateral branch length of older plants in the field was similar for both groups of plants, indicating a reduction in the growth rate of TC-derived plants from 34 to 82 weeks after propagation. Pruning and chilling methods reduced basal branch length and the number of lateral branches produced in the field, while enhancing the length of lateral branches and total buds per lateral branch. Although TC-derived blueberry plants had numbers of total flower buds and total buds per lateral branch similar to ST-derived plants, they produced more flower buds per plant. The enhanced branching framework of TC-derived plants, composed of rapidly forming basal and lateral branches, may increase photosynthesis at an early age and hasten fruit production.
Anthony H. Hatch and David R. Walker
A bell shaped, rest-intensity curve as a function of time was obtained for ‘Elberta’ peach and ‘Chinese’ apricot leaf buds growing in the field. Rest was not closely associated with fluctuating environmental temperatures, cold hardiness, or rate of respiration.
Apricot leaf buds reached the peak of their rest before peach leaf buds, and it was not as intense or as deep as it was with the peach buds. Rest was completed by both species at the same time in early January.
Alan R. Langille and P.R. Hepler
Non-induced Katahdin potato plants were treated with three anti-gibberellins: CCC, BAS-106 and BAS-111. Other plants were sprayed with GA3 and placed in an inducing chamber. All treatments were repeated the following week. After final treatment, apical, sub-apical, medial and basal leaf bud-cuttings were taken from each plant and placed 1n a mist chamber. After two weeks, cuttings were examined for tuberization. BAS-111 and CCC were associated with 3.5 and 2 fold increase, respectively, in tuberization of cuttings over the non-induced control. Although induced control cuttings exhibited 100% tuberization, application of GA to plants grown under identical conditions, reduced tuberization 20 fold. In non-induced control cuttings and those treated with CCC, basal cuttings tuberized significantly better than those taken from higher on the stem. This pattern was reversed for plants treated with BAS-111. These results will be discussed in light of current understanding of the tuberization phenomenon.
F. T. Davies Jr. and J. N. Joiner
Adventitious root formation was stimulated with foliar application of indolebutyric acid (IBA) from 1000 to 1500 mg/liter for juvenile and 2000 to 3000 mg/liter for mature leaf bud cuttings of Ficus pumila L. IBA increased cambial activity, root initial formation, and primordia differentiation and elongation. IBA stimulated rooting when applied to juvenile cuttings at 3, 5, or 7 days after experiment initiation, but had no effect on mature cuttings when applied at day 15, the final treatment period. The interaction of IBA/gibberellic acid (GA3) did not affect early root development stages, but reduced root elongation and quality once primorida had differentiated. IBA/6-(benzylamino)-9-(2-tetrahydropyranyl)-9H-purine (PBA) inhibited rooting at early initiation stages.
Sung-Do Oh and G. Bunemann
Asparagine and arginine contents in spur buds, leaf buds and terminal buds of shoot were compared in Fuji and Jonagold apple trees during dormant and growing season. Amino acid contents in dormant spur buds were significantly higher in Jonagold than in Fuji, whereas the amino acid contents in shoot bark were not different in two cultivars. Asparagine and arginine contents were considerably higher in leaf and terminal buds of shoot. This phenomenon was quite obvious in Fuji than Jonagold but there was no significant difference in asparagine and arginine contents in spur buds. Flower buds differentiated on summer pruned shoots had higher contents of asparagine and arginine as compared with weak spur buds in Fuji but this was not quite obvious in Jonagold. It suggested that the irregular spur size and poor development of spur buds in Fuji cultivar might be caused by the poor translocation of amino acids as well as nitrogen compounds from shoots and other vegetative organs.
Dehua Liu, Helen A. Norman, Gary W. Stutte, and Miklos Faust
Lipase activity was studied during endodormancy in low-chilling-requiring `Anna' and high-chilling-requiring `Northern Spy' apples (Malus domestica Borkh.). Lipase activity greatly increased in bud axes when the chilling requirement of buds was almost satisfied regardless of the absolute chilling needed. Lipase activity greatly increased in `Anna' after 400 chill units (CU) and in `Northern Spy' after 2600 CU. This corresponded with an increase in budbreak at 22 to 24C. The increase in lipase activity also coincided with the release of water in buds from the bound to the free form. We propose that lipase(s) activity is an integral part of breaking dormancy and that lipase participates in causing changes in membrane lipid composition that coincides with releasing water into the free form.