Raper C D, Vessey J K, Henry L T
Dept of Soil Science, North Carolina State Univ., Raleigh 27695-7619.
Physiol Plant. 1991;81:183-9.
Diurnal patterns of net NO3- uptake by nonnodulated soybean [Glycine max (L.) Merr. cv. Ransom] plants growing in flowing hydroponic culture at 26 and 16 degrees C root temperatures were measured at hourly intervals during alternate days of a 12-day growth period. Ion chromatography was used to determine removal of NO3- from the culture solution. Day and night periods of 9 and 15 h were used during growth. The night period included two 6-h dark periods and an intervening 3-h period of night interruption by incandescent lamps to effect a long-day photoperiod and repress floral initiation. At both root temperatures, the average specific rates of NO3- uptake were twice as great during the night interruption period as during the day period; they were greater during the day period than during the dark periods; and they were greater during the dark period immediately following the day period than during the later dark period that followed the night interruption. While these average patterns were repetitious among days, measured rates of uptake varied hourly and included intervals of net efflux scattered through the day period and more frequently through the 2 dark periods. Root temperature did not affect the average daily specific rates of uptake or the qualitative relationships among day, dark and night interruption periods of the diurnal cycle.
在12天的生长周期中，每隔一天，以小时为间隔，测量了在26℃和16℃根温下，生长于流动水培中的非结瘤大豆[Glycine max (L.) Merr. cv. Ransom]植株对硝酸根的净吸收日模式。采用离子色谱法测定培养液中硝酸根的去除量。生长期间采用9小时的白天时段和15小时的夜间时段。夜间时段包括两个6小时的黑暗时段和一个中间3小时的夜间中断时段，通过白炽灯进行夜间中断以实现长日照光周期并抑制花芽分化。在两个根温条件下，夜间中断时段的硝酸根平均吸收比速率是白天时段的两倍；白天时段的硝酸根平均吸收比速率大于黑暗时段；白天时段之后紧接着的黑暗时段的硝酸根平均吸收比速率大于夜间中断之后的黑暗时段。虽然这些平均模式在不同天数之间是重复的，但实测吸收速率每小时都有所变化，且包括白天时段以及更频繁地在两个黑暗时段中出现的净外流间隔。根温不影响平均每日吸收比速率，也不影响昼夜循环中白天、黑暗和夜间中断时段之间的定性关系。
