The Influence of Irradiance on Rate of Development and Components of Yield In Barley

A field study was conducted to investigate the effects of variation in levels of daily irradiance on the level of spike-let abortion and the rate of development using two cultivars of spring barky ( Hordeum vulgare L.), Schooner and Weeah. Three different irradiance treatments were imposed from the cessation of spikelet primordia initiation until anthesis: a reduced irradiance treatment (high competition treatment, HCT); an untreated control for medium competition treatment; MCT); and an increased amount of irradiance (low competition treatment. LCT). Variation, in natural daily irradiance (MCT) was imposed by either shading plants with shadecloth (HCT) or by exposing plants to relatively low inter-row irradiance competition effects by obstructing adjoining plant rows with plastic mesh (LCT). The duration of the spikelet growth phase was longer by 5 days (Schooner) and 9 days (Weeah) for HCT when compared to MCT, but there was no difference in its duration between LCT and MCT. Spikelet abortion occurred at 8–16 days before anthesis, but this was dependent on treatment. LCT For both cultivars showed a trend towards higher spikelet numbers per spike, although the increase was not significant over MCT, and HCT was significantly lower in both cultivars. Grain yield and biomass were lower (P < 0.05) for HCT compared to both LCT and MCT.     

不同光照条件下新疆小拟南芥可塑性反应的生理生化特性

为揭示出小拟南芥可塑性反应的生理生化特点,采用不同光照强度处理新疆小拟南芥,研究其主要生理生化指标,结果表明:在一定的条件下,叶绿素含量随着光照强度的增大而增大。在抗氧化系统中,过氧化氢酶活性与生长光强的变化不一致。膜透性则随着光照强度的增大而增大。新疆小拟南芥组织中抗氧化系统的加强是响应强光的一种措施,显现出极强的可塑性。     

Einfluß des Lichtangebotes auf das Wachstum und die biologische Stickstoff-Fixierung von Weißklee (Trifolium repens L.)

Influence of light quantity on growth and biological nitrogen fixation of white clover ( Trifolium repens L.)
The influence of photon irradiance (E_p; 100 to 500 μmol m⁻² s⁻¹) and of the photoperiod (16 or 11 h) on growth and nitrogenase activity of nodulated white clover plants was studied in growth chambers at two nitrate levels (1.0 and 7.5 mM NO₃⁻).
Total dry mass production, the root proportion and nitrogenase activity increased with increasing E_p and photoperiod. Nitrogenase activity generally increased proportionally to root mass. Only at low E_p (100 μmol m⁻² s⁻¹) and under a short photoperiod (11 h) was the specific nitrogenase activity per unit root mass reduced. An abrupt change in E_p led to a rapid and parallel change in nitrogenase activity and relative growth rate.
A higher NO₃⁻ concentration in the nutrient solution (7.5 mM) led to a marked decrease in specific nitrogenase activity, but increased growth between 200 and 500 μmol m⁻² s⁻¹ during early development only. At 100 μmol m⁻² s⁻¹, there was no growth response to nitrate, although its effect on nitrogenase activity was more marked than at a higher E_p.
The results show that with changing light quantity, biological nitrogen fixation of white clover adapts to the existing demand for nitrogen and does not limit growth except during early development, even when light supply is low.     

Effects of Relative Light Intensity on the Growth,Yield and Curcumin Content of Turmeric (Curcuma longa L.) in Okinawa,Japan

Abstract

The effects of relative light intensity (RLI) on the growth, yield and curcumin content of turmeric (Curcuma longa L.) were examined in Okinawa, Japan. The plants were shaded with white nets with different mesh sizes for maintaining respective RLI. Five RLI, 100 (without shading), 82, 79, 73 and 59% in 2004?2005 and four RLI, 100, 68, 52 and 48% in 2005?2006 were evaluated. In the first experiment, plant height increased markedly, but the number of leaves and tillers, and SPAD value increased slightly in the plants grown at 59?82% RLI compared with control (without shading). Turmeric shoot biomass and yield increased significantly at 59?82% RLI and they were highest at 73% RLI in the first experiment. Curcumin content of turmeric increased markedly at 59?73% RLI as compared with the control in the first experiment. Similar results in plant growth, shoot biomass, yield and curcumin content were obtained in the second experiment, but the effects of RLIs were smaller than in the first experiment because of late planting. This study indicates that turmeric is a partial shade-tolerant plant that could be cultivated at around 59?73% RLI for higher yield and curcumin content in Okinawa. However, the degree of RLI required for better turmeric cultivation may vary with the place, year and irradiance level.     

桑树叶片光合诱导对光强转换的响应

在温室条件下, 以桑树品种“蒙古桑”幼苗为试验材料, 应用气体交换和叶绿素荧光测定技术, 研究了光强转换过程中桑树叶片的光合诱导响应。结果表明: 光强由黑暗或低光转换到高光时, 桑树叶片净光合速率需要10 min的光诱导才能达到稳定状态, 其中1~2 min之内的光诱导较快(快相诱导), 8~10 min诱导较慢(慢相诱导)。当光强由黑暗转到高光时, 光量子转化效率的诱导过程滞后于光合碳同化诱导过程; 当光强由高光转到低光或黑暗时, 桑叶的光合诱导平衡速率快于光强由低光或黑暗转到高光时的平衡速率。说明光量子转化效率的光诱导受碳同化诱导过程的限制, 光量子转化效率的诱导主要通过调控PSⅡ开放的反应中心比例来实现。     

Estimated and measured DNA, plant-chromosphere and erythemal-weighted irradiances at Barrow and South Pole (1979–2000)

In the last two decades as a consequence of ozone depletion there has been an increasing interest in the study of biological effects of ultraviolet radiation (UV). Spectral instruments, which provide detailed information on UV environmental conditions, have been in use systematically only for little more than a decade. These time series are still relatively short and information on spectral historical irradiance levels is not available. Many efforts have been carried out in inferring this information from other available data sets. One of them has been the use of statistical models. Spectral irradiances are available at South Pole (90°00′S 0) and Barrow (71°18′N, 156°47′W) from the NSF UV Radiation Monitoring Program since 1991. In the present paper, daily-integrated biologically weighted irradiances for these sites are inferred back to 1979 using a multi-regressive model, obtaining time series that extend near the beginning of the Antarctic ozone depletion. These datasets are unique since the daily-integrated irradiances were calculated from irradiance measured hourly at the earth’s surface. The biologically weighted irradiances are estimated from irradiance measured with broadband instruments, ozone, and solar zenith angles. From daily-integrated irradiance, monthly means were also calculated. The RMS errors between the estimated and measured daily-integrated irradiances range from 4.69 to 7.49% at South Pole and from 9.57 to 15.20% at Barrow, while the monthly mean errors vary from 2.07 to 3% and 2.95 to 3.91%, respectively. Completing the databases with spectral measurements, the resulting time series extend from 1979 to 2000. Analyzing monthly values an increase relative to 1979–1981 during all years is observed at South Pole. Largest increases are observed for DNA and plant-chromosphere weighted irradiances during October. Although at a lower rate, an increase is also observed at Barrow during the spring. Maximum monthly increase at South Pole during October is near 1200% relative to 1979–1981, while the increase at Barrow is near one tenth of that percentage. Daily-integrated irradiance shows that a slight increase was present during the spring at South Pole for the period 1979–1981 reflecting the beginning of the ozone depletion. Historical maximums of daily-integrated DNA weighted irradiance at South Pole (90°00′S, 0°00′) are about as large as summer maximums at San Diego (32°45′N, 117°11′W).     

南方气候条件下光照度和辐照度的关系

研究了在南方气候条件下,太阳光照度（E）和辐照度（三）之间的具体转换关系,试验结果表明：在晴天两者间的回归线性方程为：E=0．0137L＋0．5837;在多云天气下,两者间的换算关系式为：E=0．0109L-19．654;在阴天两者之间的换算关系式为：E=0．0096L-4．5141。