Redbud (Cercis canadensis) is a small woody ornamental legume that has a hard seed coat, which imposes physical dormancy, typical of many legumes. Redbud also possesses an internal embryo dormancy that must be overcome by stratification. In order to observe the relationship between anatomy and germination, seeds were embedded in JB-4 resin during various developmental and germination stages. The seeds were cut longitudinally with a glass bladed microtome, to observe the radicle, vascular traces and testa. It appears that the vascular traces left from the funiculus serve as a weak point in non-dormant seeds that allows the radicle to rupture the testa during germination.
Rodney Jones and Robert Geneve
Phillip A. Wadl, Robert N. Trigiano, Dennis J. Werner, Margaret R. Pooler, and Timothy A. Rinehart
China ( Li, 1944 ). Both species have desirable ornamental traits. C. chinensis, commonly known as chinese redbud, grows quickly and produces flowers at an earlier age than other species in production. It has prolific bud set and a growth habit of a
Debbie Dillion and Gerald Klingaman
Rooting experiments have been conducted with a pink flowered redbud (Cercis canadensis) in anticipation of its release to the nursery trade. Cuttings taken in May, June and August were treated with NAA or IBA at 0, 1,000, 10,000 and 20,000 ppm and rooted under mist. Rooting percentages as high as 94% have been obtained by using IBA at 20,000 ppm on cuttings taken 3 weeks after growth began. Fifty percent of cuttings taken in June rooted when treated with the highest IBA rates. Cuttings taken later than June did not root. In a separate test, terminal (semi-hardwood) cuttings making active growth were compared to sub-terminal (hardwood) cuttings. IBA and NAA application at 20,000 ppm resulted in 57% rooting for terminal cuttings while producing only 14% rooting for sub-terminal cuttings. Data will be presented on the comparison of the rooting ability of this clone as compared to seedling trees.
Servet Caliskan, Sharon T. Kester, and Robert L. Geneve
demonstrates the mechanism for dormancy release in seeds with endogenous, physiological dormancy. Eastern redbud ( Cercis canadensis ) is a good model system to illustrate dormancy maintenance and release in seeds with physiological dormancy because there is
S. Yusnita, Robert L. Geneve, and Sharon T. Kester
In vitro shoot multiplication of white Eastern redbud was successful using two-node mature explants from the initial spring flush on a woody plant medium (WPM) supplemented with benzylaminopurine (BAP). Optimal shoot proliferation was obtained at 10-15 μM BAP. Treatment with thidiazuron produced fasciated (stunted) adventitious shoots which failed to elongate. Successive subcultures increased the ability of explants to form shoots. However, shoot tip necrosis became a problem after 7-8 subcultures. Shoot tip necrosis is being studied by comparing shoot multiplication on bacto-agar vs. gelrite, increasing the Ca concentration in WPM and by trying to reduce the phenolic exudate by the explants with PVP or activated charcoal. Microshoots >3 cm long were rooted by pulse treatment on half strength WPM containing 300 μM IBA or NAA before being moved to hormone free WPM. There was a different morphology between IBA and NAA induced roots, although the number of roots were comparable. IBA treated microcuttings developed branched, fine roots, whereas NAA treated plants produced unbranched, coarse roots. Rooted microshoots were successfully acclimated to greenhouse condition.
Jimmy L. Tipton
The maximum predicted germination was 95% after 62 minutes scarification and 35 days stratification for mexican redbud (Cercis canadensis var. mexicana) and 59% after 52 minutes scarification and 73 days stratification for evergreen sumac (Rhus virens). Mexican redbud germination occurred from 24 to 31 C, evergreen sumac from 21 to 31 C, and mealy sage (Salvia farinacea) from 21 to 34 C. The maximum predicted final percent germination and the temperature at which it occurred for mexican redbud, evergreen sumac, and mealy sage was 104 at 27 C, 90 at 29 C, and 42 at 22 C, respectively. The maximum predicted maximum germination rate and the temperature at which it occurred for mexican redbud, evergreen sumac, and mealy sage was 30 at 31 C, 69 at 31 C, and 104 at 27 C, respectively. The minimum predicted inflection time and the temperature at which it occurred for mexican redbud, evergreen sumac, and mealy sage was 4 days at 28 C, 10 days at 25 C, and 3 days at 28 C, respectively.
Jimmy L. Tipton
Effect of cutting age (weeks after budbreak) and K-IBA concentration on percent rooting of Mexican redbud [Cercis canadensis var. mexicana (Rose) M. Hopkins], larchleaf goldenweed [Ericameria laricifolia (Gray) Shinners], littleleaf ash (Fraxinus greggii Gray), and evergreen sumac (Rhus virens Gray) were investigated. For cuttings treated with K-IBA, maximum predicted percent rooting from regression analysis was 88% for cuttings of Mexican redbud taken 4 weeks after budbreak and treated with 21 g·liter-1, 99% for larchleaf goldenweed taken 6 weeks after budbreak and treated with 16 g·liter-1, 86%, for littleleaf ash taken 16 weeks after budbreak and treated with 17 g·liter-1, and 24% for cuttings of evergreen sumac taken 16 weeks after budbreak and treated With 5 g·liter-1. Chemical names used: potassium salt of 1H-indole-3-butanoic acid (K-IBA).
Rodney O. Jones and Robert L. Geneve
Seed coat anatomy in the hilar region was examined in dry, imbibed and germinating seeds of Eastern redbud. A discontinuous area was observed between macrosclereid cells in the palisade layer of the seed coat which formed a hilar slit. A symmetrical cap was formed during germination as the seed coat separated along the hilar slit and was hinged by the macrosclereids in the area of the seed coat opposite to the hilar slit. The discontinuity observed in the palisade layer was the remnant of the area traversed by the vascular trace between the funiculus and the seed coat of the developing ovule. There were no apparent anatomical differences in the hilar region of the seed coat between dormant and non-dormant imbibed seeds. However, the thickened layer of mesophyll cells of the seed coat in this region and the capacity of the endospetm to stretch along with the elongating radicle may contribute to maintaining dormancy in redbud seeds.
Rodney O. Jones and Robert L. Geneve
The seedcoat anatomy in the hilar region was examined in dry, imbibed and germinating seeds of Eastern redbud (Cercis canadensis L.). A discontinuous area was observed between macrosclereid cells in the palisade layer of the seedcoat which formed a hilar slit. A cap was formed during germination as the seedcoat separated along the hilar slit and was hinged by the macrosclereids in the area of the seedcoat opposite to the hilar slit. The discontinuity observed in the palisade layer was the remnant of the area traversed by the vascular trace between the funiculus and the seedcoat of the developing ovule. There were no apparent anatomical differences in the hilar region of the seedcoat between dormant and nondormant imbibed seeds. However, the thickened mesophyll of the seedcoat in this region and the capacity of the endosperm to stretch along with the elongating radicle may contribute to maintaining dormancy in redbud seeds.
Jimmy L. Tipton
Seed scarification and stratification (moist-prechilling) requirements of Mexican redbud [Cercis canadensis var. mexicana (Rose) M. Hopk.] and evergreen sumac (Rhus virens Gray) and the effects of temperature on final percent germination, maximum germination rate, and inflection time (time to maximum germination rate) for the above species plus seeds of mealy sage (Salvia farinacea Benth.) were investigated. Maximum predicted germination from a quadratic response surface was 95% after 62 minutes of concentrated sulfuric acid scarification plus 35 days of stratification for Mexican redbud, and 59% after 52 minutes of scarification plus 73 days of stratification for evergreen sumac. Mexican redbud germinated at 24 to 31C. Predicted optima for final percent germination, maximum germination rate, and inflection time were 100% at 28C, 30% germination per day at 31C, and 4 days at 29C, respectively. Evergreen sumac germinated at 21 to 31C. Final percent germination for this species declined with increasing temperature from a predicted maximum of 52% at 21C, whereas maximum germination rate increased with temperature to a predicted maximum of 69% germination per day at 31C. Inflection time was high at both extremes with a predicted minimum of 10 days at 25C. Mealy sage germinated at 21 to 34C. Predicted optima for final percent germination, maximum germination rate, and inflection time were 96% at 25C, 104% germination per day at 27C, and 3 days at 28C, respectively.