Studies On Propagation Technology Of Celtis Julianae 'Jinye' (Golden Leaves) And Its Eco-Physiological Characteristics

Jinye Julian Hackberry (Celtis julianae 'Jinye') is a new cultivar with a great ornamental potential. To rapidly regenerate this plant for the demanded market, propagation methods, morphological characteristics, and physiological features had been investigated. The results indicated:1. In vitro culture, the better explant material was overwintering buds collected right before sprouting. The optimal medium was 1/2 MS medium supplemented with IBA 0.01 mg.L-1 and 2% sugar. The explants differentiated a large number of young shoots on MS medium containing 0.5 mg.L-1 6-BA, 0.01 mg.L-1 NAA, and 2% sugar. However, the rate of root initiation was low.2. For grafting, the best time was the early spring when the plant began active growth. One-year-old scions grafted on the two-year-old seedling stock increased both survival and growth rates, which significantly reduced the production time.3. Celtis julianae 'Jinye' has similar morphological features of its species, but slow growth rate and more round habit. The leaf size is broader than the other cultivated individuals of the species. Leaves are bright yellow (151A~144A, Royal Horticultural Society Color Chart) during the spring and summer and yellowish green (144B~143A) in fall. However, the leaves from other members of its species are always deep green (137A~B) throughout the growth season.4. The impact of different light conditions on leaf color expression had been examined. Jinye Julian Hackberry has golden leaves because its chlorophyll content was much smaller than its species. As the light intensity decreased, the chlorophyll content decreased and carotenoid content had little change. Therefore, leaves of C. julianae 'Jinye' had lighter color.5. Compared with C. julianae, the chloroplast's stroma lamellas of C. julianae 'Jinye' become loose and the chloroplast microstructure changed a lot. Both number and size of chloroplasts decreased. The specific lamellae number of granum followed the same trend.6. The light compensation point of Jinye Julian Hackberry was about 55~65 umol.m-2.s-1 and the light saturation point was around 1500-1800 umol.m-2.s-1. Diurnal photosynthetic rate showed two peaks and photosynthetic depression was observed on sunny summer days.7.After flooding stress, height, leaf area, dry mass, diameter at ground level, and the activity of ADH of Jinye Julian Hackberry had significant differences and it took a long time (about a month) to reach the normal growth. During the water deficit, the plant responded slowly for a while (about 3weeks), than showing the wilted leaves suddenly. After release from water stress, normal growth rate could be observed within a week. Obviously, C. julianae 'Jinye' is a drought tolerant plant and waterlog areas should be avoided.