Prescribed fire is used in the Sudanian savanna-woodland of West Africa as a forest management tool. An experiment was carried out to assess the effects of season of burning, and different vertical probe positions on ...Prescribed fire is used in the Sudanian savanna-woodland of West Africa as a forest management tool. An experiment was carried out to assess the effects of season of burning, and different vertical probe positions on maximum fire temperature and temperature residence time above 60℃ which is considered lethal for plant tissues. Seasons of burning considered were： an early season fire set at the beginning of the dry season （beginning of December）, mid-season fire set at the peak of the dry season （mid-January）, and a late season fire at the end of the dry season （end of March）. The effects of these fires on the germination of buried seeds of three socio-economically valuable tree species were also examined. Results indicated significant differences in maximum fire temperature and residence time with respect to season of burning and vertical probe position （p 〈 0.001）. The highest and longest lasting temperatures were observed at 20 cm above ground during early fire and at the soil surface during mid-season and late fires. This, in turn, affected germination responses of seeds buried at different soil depths. Implications of these findings in the current management practices are discussed.展开更多
An efficient protocol for plant regeneration from protoplasts of hydroxyproline(HYP)resistant cell line of Onoblychis viciaefolia was established. In SH medium supplemented with 1 mg/L 2, 4-dichlorophenoxy-acetic acid...An efficient protocol for plant regeneration from protoplasts of hydroxyproline(HYP)resistant cell line of Onoblychis viciaefolia was established. In SH medium supplemented with 1 mg/L 2, 4-dichlorophenoxy-acetic acid (2,4-D), 0.5 mg/L kinetin (KT) and 0.2 mg/L naphthalene acetic acid (NAA), the division frequency of protoplastderived cells reached uP to over 60 %, and microcalli were obtained in 5-6 wk. Upon transferring them on agar solidified MS medium plus 2 mg/L indole-3-acetic acid (IAA), shoots were induced. After cultivating them on MS medium with or without IAA, roots were regenerated.Chromosome number of all protoplast-regenerated plants examined were normal (2n=28). The protoplast-derived calli and plants grew vigorously on the medium containing 10 mmol/L HYP.展开更多
The species diversity at the regeneration stage, inflenced by different water levels, is important for community composition in the later growing season.Regeneration diversity of Carex lasiocarpa community under diffe...The species diversity at the regeneration stage, inflenced by different water levels, is important for community composition in the later growing season.Regeneration diversity of Carex lasiocarpa community under different water levels was studied at two stages, recruitment and adult, in the Sanjiang Plain, Heilongjiang Province, China.The results showed that, at the two growing stages, important value of C.lasiocarpa population and species richness of the community decreased with the increasing water level, while the Simpson and Shannon-Wiener diversity indexes and Pielou evenness index increased.Under different water levels, community diversities were higher at the recruitment stage, while population important values of C.lasiocarpa were higher at the adult stage.Indexes in vegetation evaluation must be chosen prudentially for successful restoration and effective management of wetlands, and especially for wetland restoration, the optimal time should be selected according to the restoration objectives and costs.展开更多
A plant＇s capacity to compensate for pest damage as a function of resource availability needs to be predictable in order to apply biocontrol agents effectively. In this research, it was hypothesized that a weedy plan...A plant＇s capacity to compensate for pest damage as a function of resource availability needs to be predictable in order to apply biocontrol agents effectively. In this research, it was hypothesized that a weedy plant species＇ capacity to compensate for defoliation is related to how resource availability affects a plant＇s growth trajectory. Growth rate trajectory is defined as the percent change in relative growth rate or the slope of a plant＇s relative growth rate. 90 Abutilon theophrasti, a common weed species, in cultivated fields of corn and soybean, grew in a greenhouse for 70 d under three nitrogen （N） fertilization treatments. ＂Unfertilized＂ plants were not fertilized, ＂bulk＂ fertilized plants received 0.6 g N on day 15 and ＂exponential＂ fertilized plants received a total of 0.6 g N supplied at an exponential rate of 10% per day with a starting concentration of 0.02 g N on day 15. On day 25, 15 plants in each N treatment had 75% of total leaf area removed. Biomass and reproductive compensation were determined after 50 d and 70 d of growth. Results showed that bulk plants had the greatest absolute growth, but also the greatest decline in growth rates and the least capacity for compensation. Unfertilized plants had the lowest absolute growth, but declines in growth rates were similar to bulk plants with only a slightly greater compensatory capacity. Exponential plants had intermediate absolute growth, but the least decline in growth rates and the greatest capacity for compensation. This experiment indicates that a plant＇s growth rate trajectory, and not high or low relative growth rates or N availability per se, can be used to predict a weedy plant＇s capacity to compensate for herbivory, and has implications for biocontrol of weedy species.展开更多
基金supported by the Swedish International Development Cooperation Agency (Sida)
文摘Prescribed fire is used in the Sudanian savanna-woodland of West Africa as a forest management tool. An experiment was carried out to assess the effects of season of burning, and different vertical probe positions on maximum fire temperature and temperature residence time above 60℃ which is considered lethal for plant tissues. Seasons of burning considered were： an early season fire set at the beginning of the dry season （beginning of December）, mid-season fire set at the peak of the dry season （mid-January）, and a late season fire at the end of the dry season （end of March）. The effects of these fires on the germination of buried seeds of three socio-economically valuable tree species were also examined. Results indicated significant differences in maximum fire temperature and residence time with respect to season of burning and vertical probe position （p 〈 0.001）. The highest and longest lasting temperatures were observed at 20 cm above ground during early fire and at the soil surface during mid-season and late fires. This, in turn, affected germination responses of seeds buried at different soil depths. Implications of these findings in the current management practices are discussed.
文摘An efficient protocol for plant regeneration from protoplasts of hydroxyproline(HYP)resistant cell line of Onoblychis viciaefolia was established. In SH medium supplemented with 1 mg/L 2, 4-dichlorophenoxy-acetic acid (2,4-D), 0.5 mg/L kinetin (KT) and 0.2 mg/L naphthalene acetic acid (NAA), the division frequency of protoplastderived cells reached uP to over 60 %, and microcalli were obtained in 5-6 wk. Upon transferring them on agar solidified MS medium plus 2 mg/L indole-3-acetic acid (IAA), shoots were induced. After cultivating them on MS medium with or without IAA, roots were regenerated.Chromosome number of all protoplast-regenerated plants examined were normal (2n=28). The protoplast-derived calli and plants grew vigorously on the medium containing 10 mmol/L HYP.
基金Under the auspices of the National Basic Research Program of China (No. 2009CB421103)Northeast Revitalization Program,Chinese Academy of Sciences (No. DBZX-2-024)
文摘The species diversity at the regeneration stage, inflenced by different water levels, is important for community composition in the later growing season.Regeneration diversity of Carex lasiocarpa community under different water levels was studied at two stages, recruitment and adult, in the Sanjiang Plain, Heilongjiang Province, China.The results showed that, at the two growing stages, important value of C.lasiocarpa population and species richness of the community decreased with the increasing water level, while the Simpson and Shannon-Wiener diversity indexes and Pielou evenness index increased.Under different water levels, community diversities were higher at the recruitment stage, while population important values of C.lasiocarpa were higher at the adult stage.Indexes in vegetation evaluation must be chosen prudentially for successful restoration and effective management of wetlands, and especially for wetland restoration, the optimal time should be selected according to the restoration objectives and costs.
文摘A plant＇s capacity to compensate for pest damage as a function of resource availability needs to be predictable in order to apply biocontrol agents effectively. In this research, it was hypothesized that a weedy plant species＇ capacity to compensate for defoliation is related to how resource availability affects a plant＇s growth trajectory. Growth rate trajectory is defined as the percent change in relative growth rate or the slope of a plant＇s relative growth rate. 90 Abutilon theophrasti, a common weed species, in cultivated fields of corn and soybean, grew in a greenhouse for 70 d under three nitrogen （N） fertilization treatments. ＂Unfertilized＂ plants were not fertilized, ＂bulk＂ fertilized plants received 0.6 g N on day 15 and ＂exponential＂ fertilized plants received a total of 0.6 g N supplied at an exponential rate of 10% per day with a starting concentration of 0.02 g N on day 15. On day 25, 15 plants in each N treatment had 75% of total leaf area removed. Biomass and reproductive compensation were determined after 50 d and 70 d of growth. Results showed that bulk plants had the greatest absolute growth, but also the greatest decline in growth rates and the least capacity for compensation. Unfertilized plants had the lowest absolute growth, but declines in growth rates were similar to bulk plants with only a slightly greater compensatory capacity. Exponential plants had intermediate absolute growth, but the least decline in growth rates and the greatest capacity for compensation. This experiment indicates that a plant＇s growth rate trajectory, and not high or low relative growth rates or N availability per se, can be used to predict a weedy plant＇s capacity to compensate for herbivory, and has implications for biocontrol of weedy species.
