模拟台风雨对柑桔果实膨大及其生理的影响

以人工气候室模拟台风中大气水蒸气压亏（ＶＰＤ）骤降，发现朱砂桔叶水势上升幅度大于果水势，叶果间水势差增大，致使水分向果分配，但效应短暂，而复水增加土壤水分对果膨大生长的影响更为明显和持久。控水期间果内渗透调节启动，同时叶从果中抽取更多水分也使果水势下降，复水后胁迫果的水势明显低于叶水势，使膨大生长更明显。“台风”引发的膨大生长包含被动和主动两种吸水机理，而以前者为主。模拟台风与自然台风不同，未能引起乙烯发生量加大，但引起酸性转化酶和三磷酸腺苷酶（ＡＴＰａｓｅ）活性上升，有助于同化产物积累和渗透吸水及需能代谢增强。     

The relationship between sap flow rate and diurnal change of tangential strain on inner bark in Cryptomeria japonica saplings

The relationship between sap flow rates and diurnal fluctuation of stems was investigated in cloned 3-year-old saplings of Cryptomeria japonica D. Don grown in a phytotron with irrigation every 2 days. The improved stem heat balance method and a strain gauge were used to measure sap flow rate and diurnal fluctuation of the stem. The sap flow rate reacted to lighting conditions, increasing and decreasing immediately after lights-on and lights-off, respectively. The tangential strain on the surface of the inner bark exhibited a reaction that followed but opposed the reaction of the sap flow rate to lighting conditions. Based on the changes in sap flow rate, there seemed to be four phases in diurnal sap flow: phase A₁ began with lights-on, when the sap flow rate increased, and lasted about 2 hours. In the following phase, A₂, the sap flow rate remained almost constant at 1.3 g/min for about 10 h, and then declined for about 2 h as lights-off approached. In phase B, the early period of darkness, the sap flow declined quickly and then more slowly, for about 4 h, until the start of the second dark period, phase C, when the sap flow rate became almost constant at 0.05 g/min for about 6 h. The first derivative of each sap flow rate and the corresponding tangential strain were calculated, and the results indicated a negative correlation between the two variables in all periods. In particular, the relationship between the first derivative values exhibited a highly negative correlation in phases A₁ and B, expressed as a primary formula. Sap flow rate was found to continue for some time after lights-off, and this compensated for reduced evaporative effects, albeit at a slow rate, over 4 h. The total amount of sap flow in the dark was only about 9% of that in the light, disregarding transpiration in the dark for simplicity. Thus, the total amount of sap flow responsible for swelling of the stem was about 9% of that consumed in transpiration during the light period.     

Phytotron studies to compare nitrogen losses from corn-planted soil by the 15-N balance or direct dinitrogen and nitrous oxide measurements

Summary Containers filled with soil mixed with potassium nitrate highly enriched in ¹⁵N were planted with corn (Zea mays L.) and kept in a phytotron under controlled conditions for 79 days. Soil water content was normally maintained at exactly 60% water-holding capacity (–33 kPa), but it was increased several times to 85% (–5 kPa) for short periods to favour denitrification. The soil headspace was sealed from the phytotron atmosphere and aerated by a continuous stream of air. Nitrous oxide emission was measured by estimating the N₂O concentration differences in the air entering and leaving the containers. Emission of N₂ was estimated by mass spectroscopy from changes in the N₂ composition in the temporarily enclosed soil headspace. Both methods were carefully checked for accuracy by different tests. At specific times during the experiment the distribution of ¹⁵N between plants and soil was determined and a ¹⁵N balance established. Emission of N gases peaked at times of increased water content and reached maxima of 149 and 142 g N pot^–1 day^–1 for N₂O and N₂, respectively. While N losses of 5% ± 2% were indicated by the ¹⁵N balance, only 1.1% ± 0.3% loss from 2.7 g applied N was estimated from the N₂O and N₂ measurements after 79 days. Possible reasons for these differences are discussed.     

人工气候室条件下冬小麦DH群体苗期光合性状基因定位实验设计与实施

利用人工气候室提供稳定和一致的植物生长环境条件,进行冬小麦双单倍体(DH)群体苗期光合性状基因定位的实验设计。结果表明,该方法可以减轻环境误差,使测定结果更加稳定和准确。     

水稻耐热性的人工气候室鉴定方法研究

以30个耐热性有差异的水稻株系为材料,利用人工气候室模拟自然条件下的高温环境,选择抽穗开花时期的耐热性鉴定时期,以耐热系数为水稻耐热性的评价指标,对水稻耐热性的人工气候室鉴定方法进行了研究。结果表明,该方法可以模拟自然条件下的高温环境,准确控制温度、湿度和光照条件,重复性好,结果准确可靠。