Cryogenic wedges developed due to very cold,rather arid conditions during the maximum of the last cold event when the drying up of the neighboring China Sea resulted in the failure of the East Asian Monsoon.As the cli...Cryogenic wedges developed due to very cold,rather arid conditions during the maximum of the last cold event when the drying up of the neighboring China Sea resulted in the failure of the East Asian Monsoon.As the climate ameliorated and the Monsoon rains reappeared,ice-wedges developed.Further warming permitted thawing of the ice infillings accompanied by replacement of the ice by sediments partly from the host ground as well as from the surface by wind or sheet wash.In cases of extreme surface water flow on slopes after 10 ka B.P.,small baydjarakhs typically c.50 cm high developed,only to have the resulting hollows infilled by sediments carried by wind and/or sheet wash.These shallow structures form a network on top of many of the cryogenic wedges.This complex history makes dating the ages of the wedges difficult using OSL methodology.Unfortunately,past field work ignored the problem of the angle of the cut face to the direction of the wedge infilling when sampling the contents of the narrow wedges,resulting in potential contamination of the samples with the host sediment.Sampling of the larger deposits should be alright,but the likelihood of contamination makes the interpretation of the resulting OSL dates from the narrow wedges questionable.Primary wedges consisting of primary mineral infillings should still have similar OSL dates with depth for a given wedge,but the distinction between ice-wedge infillings and soil wedges is difficult since both can exhibit older dates of the infillings with depth.The available data suggests that ice-wedges were significantly more common than sediment-filled primary wedges.A protocol to avoid having to obtain large numbers of OSL dates by more careful field sampling and the use of grain size determinations is provided in the Appendix.展开更多
The lack of suitable early selection parameters means that traditional rubber breeding for yield is time consuming and inefficient. Laticifer is a tissue specific fo natural rubber biosynthesis and storage in rubber t...The lack of suitable early selection parameters means that traditional rubber breeding for yield is time consuming and inefficient. Laticifer is a tissue specific fo natural rubber biosynthesis and storage in rubber tree. The number of the secondary laticifers in the trunk bark tissues is positively correlated with rubber yield in the matured rubber trees that are regularly tapped. In the present study the rubber yield from 280 of 4–5 year-old virgin trees from7 cross combinations was compared with the number o newly differentiated secondary laticifers caused by tapping. Results showed that the number of tapping induced lines of secondary laticifers varied in differen germplasm and was positively related to the rubber yield indicating this could be used as a suitable parameter fo early evaluation of yield potential of rubber trees.展开更多
文摘Cryogenic wedges developed due to very cold,rather arid conditions during the maximum of the last cold event when the drying up of the neighboring China Sea resulted in the failure of the East Asian Monsoon.As the climate ameliorated and the Monsoon rains reappeared,ice-wedges developed.Further warming permitted thawing of the ice infillings accompanied by replacement of the ice by sediments partly from the host ground as well as from the surface by wind or sheet wash.In cases of extreme surface water flow on slopes after 10 ka B.P.,small baydjarakhs typically c.50 cm high developed,only to have the resulting hollows infilled by sediments carried by wind and/or sheet wash.These shallow structures form a network on top of many of the cryogenic wedges.This complex history makes dating the ages of the wedges difficult using OSL methodology.Unfortunately,past field work ignored the problem of the angle of the cut face to the direction of the wedge infilling when sampling the contents of the narrow wedges,resulting in potential contamination of the samples with the host sediment.Sampling of the larger deposits should be alright,but the likelihood of contamination makes the interpretation of the resulting OSL dates from the narrow wedges questionable.Primary wedges consisting of primary mineral infillings should still have similar OSL dates with depth for a given wedge,but the distinction between ice-wedge infillings and soil wedges is difficult since both can exhibit older dates of the infillings with depth.The available data suggests that ice-wedges were significantly more common than sediment-filled primary wedges.A protocol to avoid having to obtain large numbers of OSL dates by more careful field sampling and the use of grain size determinations is provided in the Appendix.
基金supported by the National Natural Science Foundation of China (31300504)the Earmarked Fund for China Agriculture Research System (CARS-34-GW1)
文摘The lack of suitable early selection parameters means that traditional rubber breeding for yield is time consuming and inefficient. Laticifer is a tissue specific fo natural rubber biosynthesis and storage in rubber tree. The number of the secondary laticifers in the trunk bark tissues is positively correlated with rubber yield in the matured rubber trees that are regularly tapped. In the present study the rubber yield from 280 of 4–5 year-old virgin trees from7 cross combinations was compared with the number o newly differentiated secondary laticifers caused by tapping. Results showed that the number of tapping induced lines of secondary laticifers varied in differen germplasm and was positively related to the rubber yield indicating this could be used as a suitable parameter fo early evaluation of yield potential of rubber trees.
