Figured black walnut lumber is a specialty wood product that commands a high price for manufacturing fine furniture and interior paneling. Two common figured grain patterns occur in walnut;they are known as “fiddle-b...Figured black walnut lumber is a specialty wood product that commands a high price for manufacturing fine furniture and interior paneling. Two common figured grain patterns occur in walnut;they are known as “fiddle-back” or “curly” grain, depending on the number of horizontal lines visible in the grain of the finished wood. The occurrence of figured walnut in nature is rare and unpredictable. Trees that have consistent figured patterns throughout the log are of exceptional value. Conversely, trees with partial or spotty figured patterns are considered defective and are reduced in value. Conventional breeding of seedlings, or cloning figured trees by grafting, are possible methods to propagate figured wood in walnut. The value of such material, however, will depend on figure being expressed predictably. For breeding to succeed, the trait of interest must be genetic and heritable. For clonal propagation to be effective, the trait must be reproduced true-to-type. In this study, we evaluate the grain pattern of both grafted and seedling walnut from several highly figured wild selections. Logs from grafted trees of three clones propagated in the 1970s in Kansas were evaluated. Only one log from one clone showed some figure in its lumber. Ten-year-old seedlings from the figured walnut clone “Lamb” were grown and cut in Indiana and evaluated for figured grain, and none showed any sign of figured grain developing. Our conclusion is that figured grain in black walnut does not propagate true-to-type through grafting or by growing open-pollinated seed. Although evidence of some genetic control of figure was found, environmental and other factors appear to play a greater role.展开更多
The aim of this study was to assess the effect of long-term in vitro sub-culturing on the varietal degeneration of three sweet potato varieties, namely, Monate, Mokone and Ndou which were sub-cultured for 32, 23 and 1...The aim of this study was to assess the effect of long-term in vitro sub-culturing on the varietal degeneration of three sweet potato varieties, namely, Monate, Mokone and Ndou which were sub-cultured for 32, 23 and 12 generations, respectively. Each generation was cultured in a media which is made from 4.43 g/L Murashige and Skoog （MS）, 30 g/L sucrose and 2 g/L gelrite, respectively, and grown under 16 h light and 8 h dark photoperiod for 30 d. For each generation, 45 plantlets were acclimatized for two months in a glasshouse. Data on in vitro growth performance and 11 morphological characteristics during acclimatization were recorded. Early root and shoot formation was observed after the 27th and 21st sub-cultured generations of Monate and Mokone, respectively. During acclimatization, plantlets from the same variety showed differences in morphological traits such as leaf colour, abaxial leaf pigmentation, vine pigmentation, petiole pigmentation, leaf wrinkling and flowering. However, the rate of these morphological differences is random and irrespective to increase in sub-culturing. Therefore, to understand the genetic base of these morphological variability, two plantlets from each variety were subjected to genetic analysis by using five simple sequence repeat （SSR） primers （IB-242, IB-318, IB-255F, 1B-248 and IB-255）. Although SSR loci IB-255F and IB-318 could distinguish between the three varieties, there were no allelic polymorphisms detected in plantlets from the same varieties. Therefore, long-term sub-culturing do not leads to quality degeneration in the three sweet potato varieties.展开更多
针对故障转移消弧装置发生首端断线故障,装置不能准确选相并可靠动作,可能会进一步发生变电站相间短路故障的问题,在某10 k V配电真型试验场进行了故障接地转移装置首端断线故障试验,分析了配电网首端断线故障特征。试验结果表明,线路...针对故障转移消弧装置发生首端断线故障,装置不能准确选相并可靠动作,可能会进一步发生变电站相间短路故障的问题,在某10 k V配电真型试验场进行了故障接地转移装置首端断线故障试验,分析了配电网首端断线故障特征。试验结果表明,线路首端断线故障与单相接地故障的母线电压变化有相似之处,故障转移消弧装置仅利用中性点位移电压的变化和相电压的变化来判断是否发生单相接地故障是不可靠的,装置会出现选相错误的现象,应增加零序电流的判据条件加以限制。展开更多
文摘Figured black walnut lumber is a specialty wood product that commands a high price for manufacturing fine furniture and interior paneling. Two common figured grain patterns occur in walnut;they are known as “fiddle-back” or “curly” grain, depending on the number of horizontal lines visible in the grain of the finished wood. The occurrence of figured walnut in nature is rare and unpredictable. Trees that have consistent figured patterns throughout the log are of exceptional value. Conversely, trees with partial or spotty figured patterns are considered defective and are reduced in value. Conventional breeding of seedlings, or cloning figured trees by grafting, are possible methods to propagate figured wood in walnut. The value of such material, however, will depend on figure being expressed predictably. For breeding to succeed, the trait of interest must be genetic and heritable. For clonal propagation to be effective, the trait must be reproduced true-to-type. In this study, we evaluate the grain pattern of both grafted and seedling walnut from several highly figured wild selections. Logs from grafted trees of three clones propagated in the 1970s in Kansas were evaluated. Only one log from one clone showed some figure in its lumber. Ten-year-old seedlings from the figured walnut clone “Lamb” were grown and cut in Indiana and evaluated for figured grain, and none showed any sign of figured grain developing. Our conclusion is that figured grain in black walnut does not propagate true-to-type through grafting or by growing open-pollinated seed. Although evidence of some genetic control of figure was found, environmental and other factors appear to play a greater role.
文摘The aim of this study was to assess the effect of long-term in vitro sub-culturing on the varietal degeneration of three sweet potato varieties, namely, Monate, Mokone and Ndou which were sub-cultured for 32, 23 and 12 generations, respectively. Each generation was cultured in a media which is made from 4.43 g/L Murashige and Skoog （MS）, 30 g/L sucrose and 2 g/L gelrite, respectively, and grown under 16 h light and 8 h dark photoperiod for 30 d. For each generation, 45 plantlets were acclimatized for two months in a glasshouse. Data on in vitro growth performance and 11 morphological characteristics during acclimatization were recorded. Early root and shoot formation was observed after the 27th and 21st sub-cultured generations of Monate and Mokone, respectively. During acclimatization, plantlets from the same variety showed differences in morphological traits such as leaf colour, abaxial leaf pigmentation, vine pigmentation, petiole pigmentation, leaf wrinkling and flowering. However, the rate of these morphological differences is random and irrespective to increase in sub-culturing. Therefore, to understand the genetic base of these morphological variability, two plantlets from each variety were subjected to genetic analysis by using five simple sequence repeat （SSR） primers （IB-242, IB-318, IB-255F, 1B-248 and IB-255）. Although SSR loci IB-255F and IB-318 could distinguish between the three varieties, there were no allelic polymorphisms detected in plantlets from the same varieties. Therefore, long-term sub-culturing do not leads to quality degeneration in the three sweet potato varieties.
文摘针对故障转移消弧装置发生首端断线故障,装置不能准确选相并可靠动作,可能会进一步发生变电站相间短路故障的问题,在某10 k V配电真型试验场进行了故障接地转移装置首端断线故障试验,分析了配电网首端断线故障特征。试验结果表明,线路首端断线故障与单相接地故障的母线电压变化有相似之处,故障转移消弧装置仅利用中性点位移电压的变化和相电压的变化来判断是否发生单相接地故障是不可靠的,装置会出现选相错误的现象,应增加零序电流的判据条件加以限制。
