| Limber pine (Pinus flexilis James), originated from North America, is kinds of superior plant resources for its ecological, economic and societal values. Introduced provenances of limber pine (Pinus flexilis James) were cultivated in nursery at Beijing,Hebei and Inner Mongolia. Contrast trials about seed vigor, the adaptability and drought adaptation of seedlings were carried out. The provenances suitable to be cultivated in nursery in Northern China were selected. The objective of the study was to provide a theoretical basis for selecting good provenance with high adaptation and strong resistance to adverse environment which adapt to the purpose of afforestation in China's arid and semi-arid areas. The results show as follows: (1)At a certain temperature 40℃, humidity 100 %, 96 h, the seed germination rate of five provenances by artificial ageing treatment declined. It dropped significantly on Rs and Rsd. Their germination rates were 64.1% and 62.8 % espectively. The activity indexes were 38.1% and 10.3%. The seed germination rate of provenance Rg and Rsi declined smaller, which showed a certain anti-ageing characteristics. Seed vigor stronger.(2)There was a correlation between the endogenous hormone, the activity of malondialdehyde (MDA) and activity index in seed endosperm. In the germination process, the content of hormone, activity of the provenance Rsi and Rsd after the aging can still maintain at a high level, the content of MDA increased less. The provenance Rsi and Rsd showed strong anti-ageing properties.(3)Vernalization: Seeds were immersed in 45℃water bath for 1d, then transfored to cold water for 2 d, finally mixed with sand (seeds: sand = 1:3), and cultured in room temperature. This treatment increased the germination rate and the nursery germination rate of the different kinds of provenance.(4)The height of rhythm of the one-year-old seedlings in Jiufeng, Radish and Dongling: beginning in the end of June and the beginning of July, the fastest growth period in August, stopping grow in the end of September and the early October, growing late a month's time in Inner Mongolia. Diameter growth rhythm: mid-June growth, in early September began to grow rapidly; the growth peak in early October, stop to grow in November late.The annual growth of seedlings in height in Dongling on Rs,Rg and Rl were the largest, they were 8.0 cm, 7.6 cm and 6.9 cm. Largest, nurseries of Rsd in Jiufeng is 7.6 cm; The diameter value (0.268 cm) of Rs is the largest in Luobodi. However, provenance Rg, Rsd and Rl in Dongling was the largest; they were 0.269 cm, 0.286 cm and 0.290 cm respectively. The average length of the main root of the different kinds of provenance in Dongling were the largest, at all levels, the number of lateral roots was the most, the rate of stems to root was the smallest in Dongling, that shows a certain drought-resistant property. The survival rate through the winter was higher than 70%, That shows a cold-resistant property.(5)The limber pine is a high water potential delay dehydration drought-tolerant species. The water potential of provenances Rsi and Rsd reduced slowly with the drought stress level increase.The activity of CAT, SOD, PPO and APX increased with the process of the drought stress. In particular, the activity of the provenance Rsd changed greatly, the ability to resist drought stress is stronger. Enzymes variation of provenances Rs are relatively small. Chlorophyll a, b and Pro content of Rs, Rg, Rsd and Rl are significantly increased in the process of drought stress. Pro content of Rg and Rsd increased obviously during the severe drought resistance, they are 41.9 times and 48.4 times respectivelt compared with the normal water condition. TheΔ13C value of the roots, stems, leaves of Rs was the smallest in Inner Mongolia. It is more adaptable to grow in Inner Mongolia. TheΔ13C value of Rg, Rsd and Rl was the smallest in Dongling and LuoBoDi, and the value in Inner Mongolia was the biggest.
|
PDF Full Text Request