Plough pans （PPs）, common in the black-soil region of northeastern China, have significant effects on the root systems of crops. We conducted a field experiment to study the distribution of soybean roots under the i...Plough pans （PPs）, common in the black-soil region of northeastern China, have significant effects on the root systems of crops. We conducted a field experiment to study the distribution of soybean roots under the influence of PPs. The soybean roots showed compensatory growth above the PP, with higher root length and weight in soil with a PP compared to those without a PP. Roots were heavier and longer in the 15-75 cm soil layer without a PP than with a PP. Soil porosity was lower in the PP and the soil below the PP, which likely decreased the oxygen content of the soil and induced more growth of roots above the PP. The PP is also likely to decrease infiltration of rain-water and hinder the migration of nitrate downward, which in turn increased the density and length of soybean root hairs, which, hence, promoted growth.展开更多
Undisturb ed soil cores of loamy clay plough pan were subjected to the treatments of freezing and thawing in laboratory. The effects of frost action on its bulk density, porosity, and hydraulic conductivity were inves...Undisturb ed soil cores of loamy clay plough pan were subjected to the treatments of freezing and thawing in laboratory. The effects of frost action on its bulk density, porosity, and hydraulic conductivity were investigated. The results indicate that freezing and thawing significantly reduced the bulk density of plough pan and increased its porosity and hydraulic conductivity. The reduction in the bulk density was closely related to the average daily soil minimum temperature and soil water content.展开更多
Rice is often grown as multiple seasons in one year,alternating between flooded and upland systems.A major constraint,introduced from the flooded system,is a plough pan that may decrease rooting depth and productivity...Rice is often grown as multiple seasons in one year,alternating between flooded and upland systems.A major constraint,introduced from the flooded system,is a plough pan that may decrease rooting depth and productivity of follow-on upland rice.Roots penetrating the plough pan under flooded rice system can leave a legacy of weaker root growth pathways.Deeper rooting rice cultivars could have a bigger impact,but no direct evidence is available.To explore whether a deep rather than a shallow rooting rice cultivar grown in a flooded cropping cycle benefited deeper root growth of follow-on rice in an upland,reduced tillage cropping cycle,a simulated flooded paddy in greenhouse was planted with deep(Black Gora) and shallow(IR64) rooting cultivars and a plant-free control.Artificial plough pans were made in between the topsoil and subsoil to form different treatments with no plough pan(0.35 MPa),soft plough pan(1.03 MPa) and hard plough pan(1.70 MPa).After harvest of this ‘first season’ rice,the soil was drained and undisturbed to simulate zero-tillage upland and planted rice cultivar BRRI Dhan 28.The overall root length density(RLD),root surface area,the numbers of root tips and branching of BRRI Dhan 28 did not vary between plough pan and no plough pan treatments.Compared with the shallow rooting rice genotype,the deep rooting rice genotype as ‘first season’ crop produced 19% greater RLD,34% greater surface area and 29% more branching of BRRI Dhan 28 in the subsoil.In the topsoil,however,BRRI Dhan 28 had 28% greater RLD,35% greater surface area and 43% more branching for the shallow rather than deep rooting genotype planted in the ‘first season’.The results suggested that rice cultivar selection for a paddy cycle affects root growth of a follow-on rice crop grown under no-till,with benefits to subsoil access from deep rooting cultivars and topsoil proliferation for shallow rooting cultivars.展开更多
基金supported by the National Natural Science Foundation of China (51239009,41301288,51479032 and 51409213)the Postdoctoral Science Foundation of China (2014M561317)+2 种基金the Heilongjiang Postdoctoral Financial Assistance,China (LBH-Z13023)the Heilongjiang Provincial Department of Education Science and Technology Research Project,China (12541039)the Young Talents Project of Northeast Agricultural University,China (14QC48)
文摘Plough pans （PPs）, common in the black-soil region of northeastern China, have significant effects on the root systems of crops. We conducted a field experiment to study the distribution of soybean roots under the influence of PPs. The soybean roots showed compensatory growth above the PP, with higher root length and weight in soil with a PP compared to those without a PP. Roots were heavier and longer in the 15-75 cm soil layer without a PP than with a PP. Soil porosity was lower in the PP and the soil below the PP, which likely decreased the oxygen content of the soil and induced more growth of roots above the PP. The PP is also likely to decrease infiltration of rain-water and hinder the migration of nitrate downward, which in turn increased the density and length of soybean root hairs, which, hence, promoted growth.
文摘Undisturb ed soil cores of loamy clay plough pan were subjected to the treatments of freezing and thawing in laboratory. The effects of frost action on its bulk density, porosity, and hydraulic conductivity were investigated. The results indicate that freezing and thawing significantly reduced the bulk density of plough pan and increased its porosity and hydraulic conductivity. The reduction in the bulk density was closely related to the average daily soil minimum temperature and soil water content.
基金funded by the Commonwealth Scholarship Commission in the UK。
文摘Rice is often grown as multiple seasons in one year,alternating between flooded and upland systems.A major constraint,introduced from the flooded system,is a plough pan that may decrease rooting depth and productivity of follow-on upland rice.Roots penetrating the plough pan under flooded rice system can leave a legacy of weaker root growth pathways.Deeper rooting rice cultivars could have a bigger impact,but no direct evidence is available.To explore whether a deep rather than a shallow rooting rice cultivar grown in a flooded cropping cycle benefited deeper root growth of follow-on rice in an upland,reduced tillage cropping cycle,a simulated flooded paddy in greenhouse was planted with deep(Black Gora) and shallow(IR64) rooting cultivars and a plant-free control.Artificial plough pans were made in between the topsoil and subsoil to form different treatments with no plough pan(0.35 MPa),soft plough pan(1.03 MPa) and hard plough pan(1.70 MPa).After harvest of this ‘first season’ rice,the soil was drained and undisturbed to simulate zero-tillage upland and planted rice cultivar BRRI Dhan 28.The overall root length density(RLD),root surface area,the numbers of root tips and branching of BRRI Dhan 28 did not vary between plough pan and no plough pan treatments.Compared with the shallow rooting rice genotype,the deep rooting rice genotype as ‘first season’ crop produced 19% greater RLD,34% greater surface area and 29% more branching of BRRI Dhan 28 in the subsoil.In the topsoil,however,BRRI Dhan 28 had 28% greater RLD,35% greater surface area and 43% more branching for the shallow rather than deep rooting genotype planted in the ‘first season’.The results suggested that rice cultivar selection for a paddy cycle affects root growth of a follow-on rice crop grown under no-till,with benefits to subsoil access from deep rooting cultivars and topsoil proliferation for shallow rooting cultivars.
