This study was conducted to investigate ovule abortion of tetraploid Robinia pseudoacacia and its reasons. It was found that in the ovule development period of tetraploid R. pseudoacacia from 15 d after coronal openin...This study was conducted to investigate ovule abortion of tetraploid Robinia pseudoacacia and its reasons. It was found that in the ovule development period of tetraploid R. pseudoacacia from 15 d after coronal opening, the levels of growth-promoting endogenous hormones in abortive ovules were lower than those in normal ovules, and the level of a growth-inhibiting hormone was always higher than those in normal ovules, indicating that ovule abortion of tetraploid R. pseudoacacia might be related to abnormal endogenous phytohormones in ovules. This study laid a foundation for further study on highly sterile phenomenon of tetraploid R. pseudoacacia seeds.展开更多
The PRD （Pearl River Delta） was subjected to two transgressions respectively in the latest Pleistocene and Holocene. Position of coastal line of the latest Pleistocene transgression in some localities, especially at...The PRD （Pearl River Delta） was subjected to two transgressions respectively in the latest Pleistocene and Holocene. Position of coastal line of the latest Pleistocene transgression in some localities, especially at the center part of PRD is still uncertain. Thus quaternary sandy sediments in the central PRD are dated by OSL Optically Stimulated Luminescence） for determining the ancient coastal line. Samples are from Xiaohushan Hill at the center of PRD, where quaternary sediments deposited on a wave-cut platlbrm consist of two kinds of sediments： marine muddy-silt on the top and alluvial fine-sand in the lower part. The former is dated at 5.0-5.5 ka, which defines the time of Holocene transgression in the PRD. The alluvial fine-sand in the part is dated at 22-26 ka. For the alluvial fine-sand rests directly on a wave-cut platform, thus this wave-cut platform should have been existed before deposit of alluvial sand, i.e., formed during an earlier marine transgression that may have culminated in the sea level high at about 40 ka. The optically stimulated luminescence results are consistent with geological observations and compatible with TL （thermoluminescence） and ^14C ages from the same layers at other localities of the PRD.展开更多
文摘This study was conducted to investigate ovule abortion of tetraploid Robinia pseudoacacia and its reasons. It was found that in the ovule development period of tetraploid R. pseudoacacia from 15 d after coronal opening, the levels of growth-promoting endogenous hormones in abortive ovules were lower than those in normal ovules, and the level of a growth-inhibiting hormone was always higher than those in normal ovules, indicating that ovule abortion of tetraploid R. pseudoacacia might be related to abnormal endogenous phytohormones in ovules. This study laid a foundation for further study on highly sterile phenomenon of tetraploid R. pseudoacacia seeds.
文摘The PRD （Pearl River Delta） was subjected to two transgressions respectively in the latest Pleistocene and Holocene. Position of coastal line of the latest Pleistocene transgression in some localities, especially at the center part of PRD is still uncertain. Thus quaternary sandy sediments in the central PRD are dated by OSL Optically Stimulated Luminescence） for determining the ancient coastal line. Samples are from Xiaohushan Hill at the center of PRD, where quaternary sediments deposited on a wave-cut platlbrm consist of two kinds of sediments： marine muddy-silt on the top and alluvial fine-sand in the lower part. The former is dated at 5.0-5.5 ka, which defines the time of Holocene transgression in the PRD. The alluvial fine-sand in the part is dated at 22-26 ka. For the alluvial fine-sand rests directly on a wave-cut platform, thus this wave-cut platform should have been existed before deposit of alluvial sand, i.e., formed during an earlier marine transgression that may have culminated in the sea level high at about 40 ka. The optically stimulated luminescence results are consistent with geological observations and compatible with TL （thermoluminescence） and ^14C ages from the same layers at other localities of the PRD.
