Temperature integration where high day temperatures are compensated by lower night temperatures is one strategy that can be used to reduce energy consumption in greenhouses. Crop tolerance to temperature variation is ...Temperature integration where high day temperatures are compensated by lower night temperatures is one strategy that can be used to reduce energy consumption in greenhouses. Crop tolerance to temperature variation is a prerequisite for using such a strategy. Greenhouse experiments were conducted on tomatoes cvs, Capricia, Mecano and Cederico in order to investigate the effect of different day/night temperature regimes (24/17, 27/14 and 30/11℃) where the same mean temperature was maintained for the production and germination of pollen. In addition, fruit quality as determined by fruit firmness, dry matter content, soluble solids, titratable acids, and pH was examined at harvest and after seven and 14 days of storage. The 30/11℃ treatment significantly increased pollen production and germination compared to the 24/17℃ treatment, while the 27/14℃ treatment was generally in between the other two treatments. Fruits grown at the 27/14℃ treatment were significantly firmer, while fruits grown at 24/17℃ had higher dry matter content, soluble solids, and titratable acids compared to the other treatments. There were significant differences between cultivars with respect to firmness, dry matter, titratable acidity, and pH. The quality of the fruits changed during storage, but the storability of the tomatoes was not affected by preharvest temperature treatments. The overall conclusion was that the 27/14℃ treatment was superior to the other two temperature treatments with respect to the studied parameters.展开更多
If low night temperatures can be combined with high day temperatures, providing optimal growth conditions for plants, a significant energy saving can be achieved in greenhouses. Lowering the night temperature from 18&...If low night temperatures can be combined with high day temperatures, providing optimal growth conditions for plants, a significant energy saving can be achieved in greenhouses. Lowering the night temperature from 18°C to 10°C-11°C for 8 h had no negative effect on the CO2 exchange rate (CER) during the following light period in tomato. This was found both in plants grown in artificial light only or in combination with daylight. Allowing the temperature to increase from 20°C to about 40°C, in parallel with an increasing solar photon flux density (PFD) from 0 up to about 800 μmol·m-2·s-1 in the greenhouse during summer, progressively increased CER when the CO2 concentration was maintained at 900 μmol·mol-1. At 400 μmol·mol-1 CO2, maximum CER was reached at about 600 μmol·m-2·s-1 PFD combined with a temperature of 32°C, and leveled out with a further increase in PFD and temperature. Maximum CER at high CO2 concentration was around 100% higher than at low CO2 level. Under early autumn conditions, CER increased up to about 500 μmol·m-2·s-1 PFD/32°C at low CO2 and up to about 600 μmol·m-2·s-1 PFD/35°C at high CO2. An elevated CO2 level doubled the CER in this experiment as well. Measurements of chlorophyll fluorescence showed no effect of low night temperature, high day temperature or CO2 concentration on the quantum yield of photosynthesis, indicating that no treatment negatively affected the efficiency of the photosynthetic apparatus. The results showed that low night temperatures may be combined with very high day temperatures without any loss of daily photosynthesis particularly in a CO2 enriched atmosphere. If this can be combined with normal plant development and no negative effects on the yield, significant energy savings can be achieved in greenhouses.展开更多
By comparing two sets of quality-controlled daily temperature observation data with and without the inhomogeneity test and adjustment from 654 stations in China during 1956 2004 and 1956-2010, impacts of inhomogeneity...By comparing two sets of quality-controlled daily temperature observation data with and without the inhomogeneity test and adjustment from 654 stations in China during 1956 2004 and 1956-2010, impacts of inhomogeneity on changing trends of four percentile temperature extreme indices, including occurrences of cold days, cold nights, warm days, and warm nights with varying intensities, were discussed. It is found that the inhomogeneity affected the long-term trends averaged over extensive regions limitedly. In order to minimize the inhomogeneity impact, the 83 stations identified with obvious inhomogeneity impacts were removed, and an updated analysis of changing trends of the four temperature extreme indices with varying intensities during 1956 2010 was conducted. The results show that annual occurrences of both cold nights and cold days decreased greatly while those of warm nights and warm days increased significantly during the recent 20 years. The more extreme the event is, the greater the magnitude of changing trends for the temperature extreme index is. An obvious increasing trend was observed in annual occurrences of cold days and cold nights in the recent four years. The magnitude of changing trends of warm extreme indices was greater than that of cold extreme indices, and it was greater in northern China than in southern China. Trends for summer occurrence of cold days were not significant. Decreasing trends of occurrences of both cold nights and cold days were the greatest in December, January, and February （DJF） but the least in June, July, and August （JJA）, while increasing trends of warm nights were the greatest in JJA. Cold nights significantly decreased from 1956 to 1990, and then the decreasing trend considerably weakened. The decreasing trend also showed an obvious slowdown in recent years for occurrence of cold days. However, increasing trends of warm nights and warm days both have been accelerated continuously since the recent decades. Further analysis presents that the evolution of the trends for occurrences of the four temperature extreme indices was dominated by the changes in northern China .展开更多
了解三江源人工草地净生态系统CO2交换（Net ecosystem CO2 exchange,NEE）的季节变化规律和主要生物因子及环境因子对这些过程的影响将有助于认识青藏高原人工草地生态系统碳循环、生态价值、功能,以及对三江源区的生态安全的重要意义...了解三江源人工草地净生态系统CO2交换（Net ecosystem CO2 exchange,NEE）的季节变化规律和主要生物因子及环境因子对这些过程的影响将有助于认识青藏高原人工草地生态系统碳循环、生态价值、功能,以及对三江源区的生态安全的重要意义。该研究利用涡度相关技术,于2005年9月1日至2006年8月31日对位于青海腹地的垂穗披碱草（Elymus nutans）人工草地的NEE及生物和环境因子进行观测,阐明NEE及其组分的动态变化特征和影响因子。三江源区人工草地生态系统的日最大吸收量为2.38gC·m^-2·d^-1,出现在7月30日。日间最大吸收率和最大排放率都出现在8月,分别为-6.82和2.95μmol CO2·m-2·s^-1。在生长季,白天的NEE主要受光合有效辐射（Photosynthetically active radiation,PAR）变化控制,同时又与叶面积指数和群落多样性交互作用,共同调节光合速率和光合效率的强度。最大光合同化速率为2.46～10.39μmolCO2·m-2·s-1,表观初始光能利用率为0.013～0.070μmolCO2·μmol-1PAR。在碳交换日过程中,NEE并不完全随着PAR的增加而增大,当PAR超过某一值（〉1200μmol·m-2·s-1）时,NEE随PAR的增加而降低。受温度的影响,生长季的生态系统的呼吸商Q10（1.8）小于非生长季节的（2.6）。生态系统呼吸主要受温度的控制,同时也受到叶面积指数的显著影响。生长季昼夜温差大并不利于生态系统的碳获取。三江源区人工草地生态系统是一个较强的碳汇,为-49.35gC·m^-2·a^-1。展开更多
在严格控制光照(350μmol photons m ~2s^1)和空气相对湿度(75％)的人工气候室内,模拟青海高原昼夜温差较大的环境条件(25℃/10℃,昼/夜),以无昼夜温差的环境条件(25℃/25℃,昼/夜)为对照,对不同环境条件下选育的青海高原338和上海沪麦...在严格控制光照(350μmol photons m ~2s^1)和空气相对湿度(75％)的人工气候室内,模拟青海高原昼夜温差较大的环境条件(25℃/10℃,昼/夜),以无昼夜温差的环境条件(25℃/25℃,昼/夜)为对照,对不同环境条件下选育的青海高原338和上海沪麦5号小麦品种的生长发育及经济性状的形成进行了比较研究。结果表明,15℃昼夜温差处理较对照条件下生长的小麦表现较好,总叶面积增加,生育期和叶片寿命延长,植株总干重和每穗粒数及千粒重均显著高于无昼夜温差条件下生长的小麦。因此,较大的昼夜温差环境条件是青海高原小麦易于高产的重要原因。 从品种看,青海的高原338在15℃昼夜温差处理下生长表现显著优于上海的沪麦5号。而在无昼夜温差条件下,两个品种的生长情况正好相反。由此可以看出,培育适合当地昼夜温差环境因素的品种也是小麦获得高产的主要因素。展开更多
文摘Temperature integration where high day temperatures are compensated by lower night temperatures is one strategy that can be used to reduce energy consumption in greenhouses. Crop tolerance to temperature variation is a prerequisite for using such a strategy. Greenhouse experiments were conducted on tomatoes cvs, Capricia, Mecano and Cederico in order to investigate the effect of different day/night temperature regimes (24/17, 27/14 and 30/11℃) where the same mean temperature was maintained for the production and germination of pollen. In addition, fruit quality as determined by fruit firmness, dry matter content, soluble solids, titratable acids, and pH was examined at harvest and after seven and 14 days of storage. The 30/11℃ treatment significantly increased pollen production and germination compared to the 24/17℃ treatment, while the 27/14℃ treatment was generally in between the other two treatments. Fruits grown at the 27/14℃ treatment were significantly firmer, while fruits grown at 24/17℃ had higher dry matter content, soluble solids, and titratable acids compared to the other treatments. There were significant differences between cultivars with respect to firmness, dry matter, titratable acidity, and pH. The quality of the fruits changed during storage, but the storability of the tomatoes was not affected by preharvest temperature treatments. The overall conclusion was that the 27/14℃ treatment was superior to the other two temperature treatments with respect to the studied parameters.
文摘If low night temperatures can be combined with high day temperatures, providing optimal growth conditions for plants, a significant energy saving can be achieved in greenhouses. Lowering the night temperature from 18°C to 10°C-11°C for 8 h had no negative effect on the CO2 exchange rate (CER) during the following light period in tomato. This was found both in plants grown in artificial light only or in combination with daylight. Allowing the temperature to increase from 20°C to about 40°C, in parallel with an increasing solar photon flux density (PFD) from 0 up to about 800 μmol·m-2·s-1 in the greenhouse during summer, progressively increased CER when the CO2 concentration was maintained at 900 μmol·mol-1. At 400 μmol·mol-1 CO2, maximum CER was reached at about 600 μmol·m-2·s-1 PFD combined with a temperature of 32°C, and leveled out with a further increase in PFD and temperature. Maximum CER at high CO2 concentration was around 100% higher than at low CO2 level. Under early autumn conditions, CER increased up to about 500 μmol·m-2·s-1 PFD/32°C at low CO2 and up to about 600 μmol·m-2·s-1 PFD/35°C at high CO2. An elevated CO2 level doubled the CER in this experiment as well. Measurements of chlorophyll fluorescence showed no effect of low night temperature, high day temperature or CO2 concentration on the quantum yield of photosynthesis, indicating that no treatment negatively affected the efficiency of the photosynthetic apparatus. The results showed that low night temperatures may be combined with very high day temperatures without any loss of daily photosynthesis particularly in a CO2 enriched atmosphere. If this can be combined with normal plant development and no negative effects on the yield, significant energy savings can be achieved in greenhouses.
基金Supported by the National Natural Science Foundation of China(40905036)
文摘By comparing two sets of quality-controlled daily temperature observation data with and without the inhomogeneity test and adjustment from 654 stations in China during 1956 2004 and 1956-2010, impacts of inhomogeneity on changing trends of four percentile temperature extreme indices, including occurrences of cold days, cold nights, warm days, and warm nights with varying intensities, were discussed. It is found that the inhomogeneity affected the long-term trends averaged over extensive regions limitedly. In order to minimize the inhomogeneity impact, the 83 stations identified with obvious inhomogeneity impacts were removed, and an updated analysis of changing trends of the four temperature extreme indices with varying intensities during 1956 2010 was conducted. The results show that annual occurrences of both cold nights and cold days decreased greatly while those of warm nights and warm days increased significantly during the recent 20 years. The more extreme the event is, the greater the magnitude of changing trends for the temperature extreme index is. An obvious increasing trend was observed in annual occurrences of cold days and cold nights in the recent four years. The magnitude of changing trends of warm extreme indices was greater than that of cold extreme indices, and it was greater in northern China than in southern China. Trends for summer occurrence of cold days were not significant. Decreasing trends of occurrences of both cold nights and cold days were the greatest in December, January, and February （DJF） but the least in June, July, and August （JJA）, while increasing trends of warm nights were the greatest in JJA. Cold nights significantly decreased from 1956 to 1990, and then the decreasing trend considerably weakened. The decreasing trend also showed an obvious slowdown in recent years for occurrence of cold days. However, increasing trends of warm nights and warm days both have been accelerated continuously since the recent decades. Further analysis presents that the evolution of the trends for occurrences of the four temperature extreme indices was dominated by the changes in northern China .
文摘了解三江源人工草地净生态系统CO2交换（Net ecosystem CO2 exchange,NEE）的季节变化规律和主要生物因子及环境因子对这些过程的影响将有助于认识青藏高原人工草地生态系统碳循环、生态价值、功能,以及对三江源区的生态安全的重要意义。该研究利用涡度相关技术,于2005年9月1日至2006年8月31日对位于青海腹地的垂穗披碱草（Elymus nutans）人工草地的NEE及生物和环境因子进行观测,阐明NEE及其组分的动态变化特征和影响因子。三江源区人工草地生态系统的日最大吸收量为2.38gC·m^-2·d^-1,出现在7月30日。日间最大吸收率和最大排放率都出现在8月,分别为-6.82和2.95μmol CO2·m-2·s^-1。在生长季,白天的NEE主要受光合有效辐射（Photosynthetically active radiation,PAR）变化控制,同时又与叶面积指数和群落多样性交互作用,共同调节光合速率和光合效率的强度。最大光合同化速率为2.46～10.39μmolCO2·m-2·s-1,表观初始光能利用率为0.013～0.070μmolCO2·μmol-1PAR。在碳交换日过程中,NEE并不完全随着PAR的增加而增大,当PAR超过某一值（〉1200μmol·m-2·s-1）时,NEE随PAR的增加而降低。受温度的影响,生长季的生态系统的呼吸商Q10（1.8）小于非生长季节的（2.6）。生态系统呼吸主要受温度的控制,同时也受到叶面积指数的显著影响。生长季昼夜温差大并不利于生态系统的碳获取。三江源区人工草地生态系统是一个较强的碳汇,为-49.35gC·m^-2·a^-1。
文摘在严格控制光照(350μmol photons m ~2s^1)和空气相对湿度(75％)的人工气候室内,模拟青海高原昼夜温差较大的环境条件(25℃/10℃,昼/夜),以无昼夜温差的环境条件(25℃/25℃,昼/夜)为对照,对不同环境条件下选育的青海高原338和上海沪麦5号小麦品种的生长发育及经济性状的形成进行了比较研究。结果表明,15℃昼夜温差处理较对照条件下生长的小麦表现较好,总叶面积增加,生育期和叶片寿命延长,植株总干重和每穗粒数及千粒重均显著高于无昼夜温差条件下生长的小麦。因此,较大的昼夜温差环境条件是青海高原小麦易于高产的重要原因。 从品种看,青海的高原338在15℃昼夜温差处理下生长表现显著优于上海的沪麦5号。而在无昼夜温差条件下,两个品种的生长情况正好相反。由此可以看出,培育适合当地昼夜温差环境因素的品种也是小麦获得高产的主要因素。
