摘要
对一代杉木纯林、二代杉木纯林和杉楠混交林中杉木根系分泌物化感作用进行了研究 ,结果表明 3种林分杉木根系分泌物都降低了杉木幼苗的鲜重、胚根长度和胚芽长度 ,抑制了杉木幼苗的生长。其中不同林分类型的杉木根系分泌液对杉木种子幼苗生长的抑制程度之间的关系是 :一代≈二代 >混交。
Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) is a major commercial tree species in South China producing about one fourth of the Nation's total high quality commercial timber. Because of the growing need for timber, pure Chinese fir plantations have been extensively replanted on the same site in successive rotations. The resulting soil degradation has resulted in poor establishment and decline in productivity which have become a major barrier to the sustainable management of Chinese fir plantations. Many documented studies suggest that allelopathy within Chinese fir plantations is likely one of the causes of soil degradation. According to some laboratory studies, extracts of Chinese fir roots, fresh leaves, and litter including phenolics such as vanillic and ferulic acids, e.g., p-hydroxybenzoic, o-coumaric, m-coumaric and p-coumaric acids, inhibit Chinese fir seed germination. However, the allelopathy of root exudates from Chinese fir plantations has never been reported. Live lateral roots from Chinese fir were collected from both pure- and mixed-species plantations. Exudates were extracted and concentrated with a revolving evaporator to four different levels of 0.5, 1, 2, and 4 times original exudate concentration. Distilled water was used as control. Twenty viable, disinfected seeds were placed on filter paper in petri dishes. Each dish was treated with 1ml of exudate, irrigated once a day, and incubated at 25℃. Each treatment had three replicates. At the end of the 20-day incubation period, fresh weight, radicle length, and stem length of germinants were recorded. Chinese fir root exudates at the concentration of 4x were shown to significantly (p < 0.05) inhibit the growth of Chinese fir germinants. The fresh weight of germinants treated with 4x root exudates of Chinese fir from the pure Chinese fir plantation of the first rotation, second rotation, and mixed-species plantation was reduced by 36.9%, 31.6% and 10.4%, respectively. Radicle length was reduced by 60.5%, 48.3% and 18.3%, respectively. And stem length treated with 4x root exudates of Chinese fir from the three plantations was reduced by 21.4%, 16.7% and 13.1%, respectively. Differences in the effects of 4x root exudates on the growth of Chinese fir germinants from the first rotation and the second rotation of pure Chinese fir plantations were insignificant (p > 0.05). Differences in effects of 4x root exudates on the growth of Chinese fir germinants from pure and mixed plantation were significant (p < 0.05). The effects of 4x root exudates of Chinese fir on the growth of Chinese fir germinants decreased in order from Chinese fir plantations of first rotation, second rotation, and mixed species. As allelopathic effects of 4x root exudates of Chinese fir from the mixed-species plantation were significantly lower than those from the pure plantation, developing mixed-species plantations might be an effective approach to resolving the problem of low productivity of replanted pure plantations.
出处
《生态学报》
CAS
CSCD
北大核心
2003年第2期393-398,共6页
Acta Ecologica Sinica
基金
中国科学院知识创新工程资助项目 ( KZCX2 -4 0 6)
中国科学院沈阳应用生态研究所创新基金资助项目( C1 2 MDSCXMS0 1 0 4 )~~
关键词
杉木
根系分泌物
化感作用
生物测定
混交林
Chinese fir
root exudates
allelopathy
bioassay
mixed plan antation
