In vitro propagation of katsura tree (Cercidiphyllum japonicum Sieb. Et Zucc), an endangered plant in China

Katsura tree (Cercidiphyllum japonicum Sieb. Et Zucc) is a long-lived, deciduous, wind-pollinated tree with dimorphic leaves. It is valued as an ornamental or a shade tree for landscape and a commercially valuable tree. Conventional propagation through seeds and cutting is not sufficient to satisfy the progressive demand. There is an exigent need to develop protocols for rapid propagation of katsura trees. This study reports an in vitro propogation of the tree. The work focused on assessing the effects of basal medium, plant growth regulators (PGRs) combination on shoot and root proliferation. Nodal sections of young shoots were used as explants. Shoot initiation, and shoot and root proliferation were carried out on basal medium and PGRs combination. The optimal response of shoot initiation was observed in woody plant medium (WPM) supplemented with 1.0 mg L−1BA and 0.01 mg L−1IBA (indole-3-butyric acid) and the percentage of shoot initiation was up to 91.66%. For proliferation of micropropagated shoots, three orthogonal designs were carried out. The result shows that the highest proliferation coefficient (4.83) was obtained in the medium containing 1.0 mg L−1 BA and 0.05 mg L−1 NAA. With the application of benzyladenine (BA) and naphthalene acetic acid (NAA), emerald green and vigorous shoots were observed. Shoots about 2.0 cm long with 4 to 6 leaves were excised and transferred to root propagation media. When the concentration of NAA was 0.5 mg L−1, the rooting percentage, mean number and mean length of roots were the highest, reaching 75% and 3.1 and 2.1 cm respectively. This efficient plant regeneration system would be helpful for genetic improvement through future conservation and biotechnology research.Keywords: Katsura tree (Cercidiphyllum japonicum Sieb. Et Zucc), shoot initiation, shoot propagation, root propagatio

Micropropagation of Vaccinium bracteatum Thunb.

Vaccinium bracteatum Thunb. is a vigorous plant that is easy to grow, can adapt to various acid soil species and has good resistance to drought. It has fewer pest problems than most other blueberry cultivars, offering an advantage rootstock for various blueberry cultivars to resist pest and disease. However, it is relatively difficult to propagate and the cuttings can be difficult to root. The present study is an investigation into the effects of the types and combination of plant growth regulators on the tissue culture system of V. bracteatum Thunb. When nodal explants were cultured on media without plant growth regulators (PGRs), the shoots did not produce new buds, while all media supplemented with PGRs significantly affected adventitious bud proliferation in woody plant medium (WPM). Upon addition of PGRs, adventitious buds occurred and significant differences were observed (P < 0.05). The shoot length and proliferation coefficient in WPM basal medium containing 0 mg L-1 KT, 2.0 mg L-1 BA, 2.0 mg L-1 ZT and 2.0 mg L-1 TDZ was much more than other concentrations. The shoot length and proliferation reached 9.64 and 7.66 cm. For rooting, significant variation was observed (P < 0.05) between different concentrations of IBA and NAA. In general, the effect of IBA was much better than NAA. The root length gradually increased with increasing concentration of IBA from 0 to 2.0 mg L-1 followed by a decrease from 2.0 to 4.0 mg L-1. The highest root length and number was 3.16 and 3.33 cm respectively when the concentration of IBA was 2.0 mg L-1.Keywords: Vaccinium bracteatum Thunb., plant growth regulator, tissue culture, micropropagationAfrican Journal of Biotechnology Vol. 12(7), pp. 695-70

Grazing intensity, duration, and grassland type determine the relationship between soil microbial diversity and ecosystem multifunctionality in Chinese grasslands: A meta-analysis

Grazing can alter soil microbial diversity and ecosystem multifunctionality (EMF) through feeding, trampling, and excreta deposition. However, it remains unclear how grazing intensity and grazing duration across Chinese grasslands affect the relationship between soil microbial diversity and EMF. Here, we conducted a meta-analysis to analyze the responses of soil microbial diversity and EMF to grazing disturbance using 54 publications with 62 sample sites from alpine grasslands and temperate grasslands in China. The results showed that EMF tended to decrease with increasing grazing duration and grazing intensity. Bacterial diversity was significantly and negatively correlated with EMF under moderate grazing, whereas fungal diversity was significantly and positively correlated with EMF under heavy grazing. Both fungal and bacterial diversity regulated the effects of grazing on EMF with grazing durations of up to 5 years. Furthermore, bacterial diversity was negatively correlated with EMF in typical steppe but positively in alpine grassland, and fungal diversity was positively correlated with EMF in typical steppe. Our results highlight the importance of microbial diversity in maintaining the multifunctionality of grassland ecosystem. We suggest that both grazing intensity, duration and grassland type should be seriously considered in the conservation of biodiversity and the sustainability of grassland ecosystem services and functions