With radical global climate change and global warming, high temperature stress has become one of major factors exerting a major Influence on crop production, In the cotton （Gossyplum hirsutum L.）-growlng areas of Ch...With radical global climate change and global warming, high temperature stress has become one of major factors exerting a major Influence on crop production, In the cotton （Gossyplum hirsutum L.）-growlng areas of China, especially in the Yangtze River valley, unexpected periodic episodes of extreme heat stress usually occur In July and August, the peak time of cotton flowering and boll loading, resulting In lower boll set and lint yield. Breeding programs for screening high temperature-tolerant cotton germplasm and cultlvars are urgent In order to stabilize yield in the current and future warmer weather conditions. In the present study, 14 cotton cultivars were quantified for in vitro pollen germination and pollen tube growth in response to temperatures ranging from 10 to 50 ℃ at 5 ℃ intervals. Different cotton genotypes varied In their in vitro pollen germination and pollen tube length responses to the different temperatures. Maximum pollen germination and pollen tube length ranged from 25.2% to 56.2% and from 414 to 682 pro, respectively. The average cardinal temperatures （Tmin,, Topt, and Tmax） also varied among the 14 cultivars and were 11.8, 27.3, and 42.7 ℃ for pollen germination and 11.8, 27.8, and 44.1 ℃ for maximum pollen tube length. Variations In boll retention and boll numbers per plant in field experiments were found for the 14 cotton cultivars and the boll retention and boll retained per plant on 20 August varied considerably In different years according to weather conditions. Boll retention on 20 August was highly correlated with maximum pollen germination （R^2 = 0.84） and pollen tube length （R^2=0.64）. A screening method based on principle component analysis of the combination of pollen characterlatics In an in vitro experiment and boll retention testing In the field environment was used In the present study and, as a result, the 14 cotton cultlvars could be classified as tolerant, moderately tolerant, moderately susceptible and susceptible to high temperature.展开更多
To improve the charging of high-temperature billets, it is crucial to produce them with zero defects and achieve effective insulation during their hot delivery. A mathematical model was developed based on the heat tra...To improve the charging of high-temperature billets, it is crucial to produce them with zero defects and achieve effective insulation during their hot delivery. A mathematical model was developed based on the heat transfer characteristics of the billet during its hot delivery. The accuracy of the model was established by studying the thermal performance of the cover of the roller conveyer for small billets in Tangshan Iron and Steel Company. The results show that the cover of the roller conveyer of the continuous casting billet can effectively reduce the heat loss during the hot delivery of the billets, and the hot loading temperature was increased by 51.6 °C. The uniformity of the temperature of the casting billet section increased substantially. The temperature difference in the casting billet section was reduced by 120 °C. The heat preservation effects of temperature holding hoods of different materials were compared. It was found that the material of the temperature holding hood has slight effect on the heat preservation.展开更多
基金Supported by the State Key Basic Research and Development Plan of China(2004CB117306)
文摘With radical global climate change and global warming, high temperature stress has become one of major factors exerting a major Influence on crop production, In the cotton （Gossyplum hirsutum L.）-growlng areas of China, especially in the Yangtze River valley, unexpected periodic episodes of extreme heat stress usually occur In July and August, the peak time of cotton flowering and boll loading, resulting In lower boll set and lint yield. Breeding programs for screening high temperature-tolerant cotton germplasm and cultlvars are urgent In order to stabilize yield in the current and future warmer weather conditions. In the present study, 14 cotton cultivars were quantified for in vitro pollen germination and pollen tube growth in response to temperatures ranging from 10 to 50 ℃ at 5 ℃ intervals. Different cotton genotypes varied In their in vitro pollen germination and pollen tube length responses to the different temperatures. Maximum pollen germination and pollen tube length ranged from 25.2% to 56.2% and from 414 to 682 pro, respectively. The average cardinal temperatures （Tmin,, Topt, and Tmax） also varied among the 14 cultivars and were 11.8, 27.3, and 42.7 ℃ for pollen germination and 11.8, 27.8, and 44.1 ℃ for maximum pollen tube length. Variations In boll retention and boll numbers per plant in field experiments were found for the 14 cotton cultivars and the boll retention and boll retained per plant on 20 August varied considerably In different years according to weather conditions. Boll retention on 20 August was highly correlated with maximum pollen germination （R^2 = 0.84） and pollen tube length （R^2=0.64）. A screening method based on principle component analysis of the combination of pollen characterlatics In an in vitro experiment and boll retention testing In the field environment was used In the present study and, as a result, the 14 cotton cultlvars could be classified as tolerant, moderately tolerant, moderately susceptible and susceptible to high temperature.
文摘To improve the charging of high-temperature billets, it is crucial to produce them with zero defects and achieve effective insulation during their hot delivery. A mathematical model was developed based on the heat transfer characteristics of the billet during its hot delivery. The accuracy of the model was established by studying the thermal performance of the cover of the roller conveyer for small billets in Tangshan Iron and Steel Company. The results show that the cover of the roller conveyer of the continuous casting billet can effectively reduce the heat loss during the hot delivery of the billets, and the hot loading temperature was increased by 51.6 °C. The uniformity of the temperature of the casting billet section increased substantially. The temperature difference in the casting billet section was reduced by 120 °C. The heat preservation effects of temperature holding hoods of different materials were compared. It was found that the material of the temperature holding hood has slight effect on the heat preservation.
