Genomic imprinting is the epigenetic phenomenon by which certain genes are expressed in a parent-of-origin-specific manner, and was first discovered in mammalian embryos. Recent studies have shown that it also occurs ...Genomic imprinting is the epigenetic phenomenon by which certain genes are expressed in a parent-of-origin-specific manner, and was first discovered in mammalian embryos. Recent studies have shown that it also occurs in developing plant seeds, and is now becoming a hot topic of biology of plant seed development. According to the previous studies on imprinted genes, imprinting mechanism and their roles in plant seed development, the current progress of genomic imprinting in plant seed development was summarized and possible strategies were proposed to deal with the problems, which could provide helpful information for further research.展开更多
The structure and dynamic succession law of natural secondary forest after severe fire interference in recent 20 years were studied by adopting the method of deducing time series from the spatial sequence of vegetatio...The structure and dynamic succession law of natural secondary forest after severe fire interference in recent 20 years were studied by adopting the method of deducing time series from the spatial sequence of vegetation in Heihe region, Heilongjiang, China. Two typical and widely distributed forest types in the study area, namely forest type A and forest type B, were selected as study subjects. Forest type A is pure broadleaf forest or broadleaf mixed forest mainly composing of superior Betula platyphylla and Populus davidiana in the area with gradient 〈25°, while forest type B is pure forest or mixed forest composing of superior Quercus mongolica and Betula davurica in the area with gradient 〉25°. Species richness, vegetation coverage, important value, and similarity index of commtmity in different layers （Herb, shrub, small tree, and arbor layers） were investigated and analyzed for the two typical forests. The results show that after fire interference, the species richness and coverage in each layer in forest type A were higher than that in forest type B. Both for forest type A and B, with elapse of post-fire years, the species richness and coverage of herbs and shrubs showed a decline tendency, while those of arbor layer present a rising tendency. Through comparison of the important values of species in each layer and analysis of community structure changes, the dynamic process of post-fire vegetation succession for forest type A and B was separately determined. Post-fire 80 years＇ succession tendency of forest type A is B. platyphylla and Larix gmelinii mixed forest. Its shrub layer is mainly composed of Corylus heterophylla and Vaccinium uliginosum, and herb layer is dominated by Carex tristachya, Athyrium multidentatum, and Pyrola incarnate; whereas, the post-fire 80 years＇ succession of forest type B is Q. mongolica and B. davurica mixed forest. Its shrub layer is mainly composed of lespedeza bicolar and corylus heterophylla and herb layer is dominated by Carex tristachya, Asparagus densiflorus, and Hemerocallis minor.展开更多
How to restore the destroyed forest after forest fire is a key question that man must face. This paper reviewed the research situation and history on the forest restoration burned blanks and summed up the research met...How to restore the destroyed forest after forest fire is a key question that man must face. This paper reviewed the research situation and history on the forest restoration burned blanks and summed up the research methods used into four scales: seed-bank scale, community scale, ecosystem scale and landscape scale. The new technologies such as GIS & Remote Sensing used to vegetation restoration were also summarized. The strategies and developing trend of vegetation restoration research on burned blanks were discussed.展开更多
The greenhouse gas （GHG） footprint of an agricultural system is a measure of the climate change impact potential （CCIP） exerted by the formation of its product（s）, its accurate quantification is essential for de...The greenhouse gas （GHG） footprint of an agricultural system is a measure of the climate change impact potential （CCIP） exerted by the formation of its product（s）, its accurate quantification is essential for determining the green value added tax of agricultural products for food markets, which in turn may drastically change the current patterns of food consumption and production towards a product life cycle oriented economy. This paper reviews the literature regarding GHG footprints of crop cultivation systems.The review concludes that few studies have fully considered the categories/ items of net GHG emissions from an investigated crop cultivation system, and thus probably led to biases in footprint estimation. Most studies to date have even neglected changes in the soil organic carbon stocks of ecosystems with annual crops, while process-oriented biogeochemical models so far have seldom been involved in GHG footprint quantification.To help with solving these problems or drawbacks, the authors propose a generic methodological framework for quantifying GHG footprints of crop cultivation systems free from grazing, which takes into account all direct/indirect GHG contributors within a ＇cradle-to-gate＇ life cycle. The authors then provide example values of some GHG emission factors, such as those from machinery operations and other agricultural inputs, extracted from the literature. In addition, direct measurements or model simulations of other major on-farm emission factors are emphasized. The need to further update this methodological framework in future studies, especially by adapting it to mixed crop-livestock production systems, is also indicated.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 National Natural Science Foundation of China(31660402)Industry Technological System Construction Project of Department of Agriculture of Yunnan ProvinceFund for Workstation of Academician Guan Chunyun from Department of Science and Technology of Yunnan Province~~
文摘Genomic imprinting is the epigenetic phenomenon by which certain genes are expressed in a parent-of-origin-specific manner, and was first discovered in mammalian embryos. Recent studies have shown that it also occurs in developing plant seeds, and is now becoming a hot topic of biology of plant seed development. According to the previous studies on imprinted genes, imprinting mechanism and their roles in plant seed development, the current progress of genomic imprinting in plant seed development was summarized and possible strategies were proposed to deal with the problems, which could provide helpful information for further research.
文摘The structure and dynamic succession law of natural secondary forest after severe fire interference in recent 20 years were studied by adopting the method of deducing time series from the spatial sequence of vegetation in Heihe region, Heilongjiang, China. Two typical and widely distributed forest types in the study area, namely forest type A and forest type B, were selected as study subjects. Forest type A is pure broadleaf forest or broadleaf mixed forest mainly composing of superior Betula platyphylla and Populus davidiana in the area with gradient 〈25°, while forest type B is pure forest or mixed forest composing of superior Quercus mongolica and Betula davurica in the area with gradient 〉25°. Species richness, vegetation coverage, important value, and similarity index of commtmity in different layers （Herb, shrub, small tree, and arbor layers） were investigated and analyzed for the two typical forests. The results show that after fire interference, the species richness and coverage in each layer in forest type A were higher than that in forest type B. Both for forest type A and B, with elapse of post-fire years, the species richness and coverage of herbs and shrubs showed a decline tendency, while those of arbor layer present a rising tendency. Through comparison of the important values of species in each layer and analysis of community structure changes, the dynamic process of post-fire vegetation succession for forest type A and B was separately determined. Post-fire 80 years＇ succession tendency of forest type A is B. platyphylla and Larix gmelinii mixed forest. Its shrub layer is mainly composed of Corylus heterophylla and Vaccinium uliginosum, and herb layer is dominated by Carex tristachya, Athyrium multidentatum, and Pyrola incarnate; whereas, the post-fire 80 years＇ succession of forest type B is Q. mongolica and B. davurica mixed forest. Its shrub layer is mainly composed of lespedeza bicolar and corylus heterophylla and herb layer is dominated by Carex tristachya, Asparagus densiflorus, and Hemerocallis minor.
文摘How to restore the destroyed forest after forest fire is a key question that man must face. This paper reviewed the research situation and history on the forest restoration burned blanks and summed up the research methods used into four scales: seed-bank scale, community scale, ecosystem scale and landscape scale. The new technologies such as GIS & Remote Sensing used to vegetation restoration were also summarized. The strategies and developing trend of vegetation restoration research on burned blanks were discussed.
基金supported jointly by the National Key R&D Program project of China[grant number 2017YFF0211704]the National Natural Science Foundation of China[grant number41761144054]
文摘The greenhouse gas （GHG） footprint of an agricultural system is a measure of the climate change impact potential （CCIP） exerted by the formation of its product（s）, its accurate quantification is essential for determining the green value added tax of agricultural products for food markets, which in turn may drastically change the current patterns of food consumption and production towards a product life cycle oriented economy. This paper reviews the literature regarding GHG footprints of crop cultivation systems.The review concludes that few studies have fully considered the categories/ items of net GHG emissions from an investigated crop cultivation system, and thus probably led to biases in footprint estimation. Most studies to date have even neglected changes in the soil organic carbon stocks of ecosystems with annual crops, while process-oriented biogeochemical models so far have seldom been involved in GHG footprint quantification.To help with solving these problems or drawbacks, the authors propose a generic methodological framework for quantifying GHG footprints of crop cultivation systems free from grazing, which takes into account all direct/indirect GHG contributors within a ＇cradle-to-gate＇ life cycle. The authors then provide example values of some GHG emission factors, such as those from machinery operations and other agricultural inputs, extracted from the literature. In addition, direct measurements or model simulations of other major on-farm emission factors are emphasized. The need to further update this methodological framework in future studies, especially by adapting it to mixed crop-livestock production systems, is also indicated.
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.
