首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   33篇
  免费   2篇
  国内免费   7篇
  2021年   7篇
  2019年   2篇
  2017年   1篇
  2016年   2篇
  2015年   1篇
  2014年   3篇
  2013年   5篇
  2011年   2篇
  2010年   4篇
  2008年   2篇
  2007年   4篇
  2006年   3篇
  2005年   2篇
  2002年   1篇
  1998年   1篇
  1996年   1篇
  1991年   1篇
排序方式: 共有42条查询结果,搜索用时 15 毫秒
1.
叶绿素含量是植物学和农业相关研究领域常用的生理指标。叶绿素含量和叶片光合功能密切相关,但是现有的叶绿素含量的测定方法无法实现叶绿素含量和光合功能的同步测定和关联分析。为解决该问题,本研究通过测定35个小麦品种旗叶的SPAD值和叶绿素荧光诱导动力学曲线,分别使用不同时间的快速叶绿素荧光动力学曲线的荧光值,以及33个常用荧光参数与对应叶片的SPAD值进行相关性分析,建立线性回归模型,并使用室内和大田两组数据对回归模型进行验证。结果表明: 通过叶绿素荧光参数RC/CSm建立的线性模型能够较好地预测叶片的SPAD值,可以用于非严重逆境胁迫下小麦叶片叶绿素相对含量的估算,从而丰富无损测定小麦叶绿素相对含量的方法,简化试验流程,实现小麦光合功能和叶绿素含量的同步测定与分析。  相似文献   
2.
This study was undertaken to investigate the effects of both nitrogen (N) and potassium (K) rates on rice resistance to brown spot, caused by the fungus Bipolaris oryzae. Rice plants (cultivar ‘Metica 1’) were grown in soil corrected with 0, 25, 50, 75 and 100 mg of N / kg (as NH4NO3) of soil as well as with 25, 50, 75, 125 and 150 mg of K / kg (as KCl) of soil. Thirty‐three‐day‐old plants were inoculated with a suspension of Bipolaris oryzae conidia and the incubation period (IP), number of lesions (NL) per cm2 of leaf area and disease severity was evaluated. Disease severity was scored at 24, 48, 72, 96, 120 and 144 h after inoculation and data were used to obtain the area under brown spot progress curve (AUBSPC). Soil plant analysis development (SPAD) index, plant dry weight and concentration of N and K in leaf tissues were also determined for both non‐inoculated (NI) and inoculated (IN) plants. Concentration of N in leaf tissue increased as the N rates in the soil increased. Concentration of K in leaf tissue increased sharply as the K rates in the soil increased for both NI and IN plants. Concentration of K in leaf tissue was not affected by N rates. The IP increased as the N rates increased, but was somewhat less impacted by increasing K rates. The NL decreased as the N rates increased. The NL dramatically declined at the highest K rates. The AUBSPC dramatically declined as the N and K rates in the soil increased. SPAD index values increased as the N and K rates in the soil increased for both NI and IN plants. Plant dry weight increased as the N and K rates in the soil increased for both NI and IN plants. Results from this study suggest that combining high N and K rates may contribute to reducing the intensity of brown spot in rice while improving plant development.  相似文献   
3.
Leaf area expansion, thickness and inclination, gas exchange parameters and relative chlorophyll content were analysed in field‐grown fig (Ficus carica L.) leaves over time, from emergence until after full leaf expansion (FLE). Ficus carica leaves showed a subtle change in shape during the early stages of development, and FLE was reached within ca. 30 days after emergence. Changes in leaf thickness and inclination after FLE demonstrated good adaptation to environmental conditions during summer in areas with a Mediterranean climate. Changes in gas exchange parameters and relative chlorophyll content showed that F. carica is a delayed‐greening species, reaching maximum values 20 days after FLE. Correlation analysis of datasets collected during leaf expansion, confirmed dependence among structural and functional traits in F. carica. Pn was directly correlated with stomatal conductance (Gs), transpiration (E), leaf area (LA) and relative chlorophyll content up to FLE. The effect of pruning on leaf expansion, a cultural technique commonly applied in this fruit tree, was also evaluated. Although leaf development in pruned branches gave a significantly higher relative leaf area growth rate (RGRl) and higher LA than non‐pruned branches, no significant differences were found in other morphological and physiological traits, indicating no pruning effect on leaf development. All studied morphological and physiological characteristics indicate that F. carica is well adapted to semiarid conditions. The delayed greening strategy of this species is discussed.  相似文献   
4.
Muranaka  S.  Shimizu  K.  Kato  M. 《Photosynthetica》2002,40(2):201-207
The effects of iso-osmotic salinity and drought stresses on leaf net photosynthetic rate (P N) in two wheat (Triticum aestivum L.) cultivars BR 8 and Norin 61, differing in drought tolerance, were compared. In drought-sensitive Norin 61, the decline of P N was larger than that in drought-tolerant BR 8. Under NaCl treatment, P N decreased in two phases similarly in both cultivars. In the first phase, photosynthetic depression was gradual without any photochemical changes. In the second phase, photosynthetic depression was rapid and accompanied with a decline of the energy conversion efficiency in photosystem 2 (PS2). Our observations suggest that the osmotic factor may induce a gradual depression of photosynthesis due to stomatal closure under both stress treatments. However, under NaCl treatment, a ionic factor (uptake and accumulation of excess Na+) may have direct effects on electron transport and cause more severe photosynthetic depression. The drought tolerance mechanism of BR 8 was insufficient to maintain single-leaf photosynthesis under salinity.  相似文献   
5.
Increasing specific leaf weight (SLW) may improve leaf apparent photosynthesis (AP) in soybean [Glycine max (L.) Merr.] but screening for SLW and AP is laborious. The Objectives of this study were (i) to determine the time course of SLW and chlorophyll concentration in experimental lines selected for differences in SLW and (ii) to evaluate the potential use of the Minolta 502 SPAD meter as a rapid estimator of SLW, AP and chlorophyll concentration in leaves of soybean. In 1991 and 1992, sixteen experimental lines representing extremes in SLW were grown at Urbana, IL, and West Lafayette, IN, with three replications at each location. SPAD values, SLW and AP were measured at the R2 (full flower), R4 (full pod) and R5 (beginning seed) growth stages. In 1992 SLW, SPAD values and chlorophyll concentration were measured weekly. Seasonal patterns of SPAD values, SLW, and chlorophyll concentration were very similar through R5. After R5, SLW continued to increase but SPAD values and chlorophyll concentration declined. SPAD values and SLW were highly correlated at the R2, R4 and R5 stages at both locations and in both years. Environmental conditions during this research were not suitable for maximum AP expression, which is likely why AP and SPAD values were correlated only at the R4 growth stage at Urbana in 1992. SPAD measurements were consistent across diverse environments and effectively separated the high SLW lines from the low SLW lines. Measuring with the Minolta 502 SPAD meter is rapid, simple and non-destructive and could be an alternative method for direct selection for SLW.Abbreviations AP- leaf apparent photosynthesis - CV- coefficient of variation - Rug- leaf rugosity - SLW- specific leaf weight - SPAD-L- SPAD value of the most recently expanded terminal leaflet - SPAD-P- SPAD value of leaflet used to measure AP - SPAD-S- SPAD value of leaflets used to measure SLW - SPAD-U- SPAD value of the terminal leaflet one node above the most recently expanded terminal leaflet The US Government right to retain a non-exclusive, royalty free licence in and to any copyright is acknowledged  相似文献   
6.
木棉叶片叶绿素荧光参数和SPAD值对干旱胁迫的响应   总被引:1,自引:0,他引:1  
采用盆栽控水干旱法模拟干旱逆境,对1年生木棉(Bombax ceiba)盆栽苗进行不同程度的胁迫处理,测定干旱胁迫时其叶片叶绿素SPAD值和荧光参数动态变化。结果表明,干旱胁迫下,木棉叶片叶绿素相对含量逐渐降低;初始荧光(Fo)随着干旱程度的加剧而呈上升趋势,而最大荧光(Fm)、潜在光化学效率(Fv /Fo)、最大光化学效率(Fv /Fm)、光化学淬灭系数(qP)和表观光合电子传递速率(ETR)下降,在中度和重度干旱胁迫时差异显著(P<0.05);非光化学淬灭系数(NPQ)变化不显著。干旱胁迫导致木棉植株出现光抑制,植株可通过降低光化学淬灭、增加热耗散的形式增强对干旱的适应能力。  相似文献   
7.
茶蚜对不同SPAD值绿色的趋性   总被引:1,自引:0,他引:1  
以茶蚜(Toxoptera aurantii)为研究对象,研究其对模拟SPAD值(叶色值)绿色和不同施氮量处理茶梢的趋性。结果表明:不同虫态茶蚜对不同SPAD值绿色的趋性存在显著差异,茶树叶片含氮量与其SPAD值之间存在显著的线性关系,茶蚜各虫态对模拟绿色趋性最强的SPAD值的相应含氮量分别为:低龄若蚜在2.83%左右,高龄若蚜在2.83%~3.14%,有翅和无翅成虫在3.14%左右;而各虫态表现出最大趋性的茶树叶片相应含氮量分别为:低龄若蚜在2.64%~3.13%,高龄若蚜在2.68%~2.83%,无翅成虫在2.42%~2.84%,有翅成虫在2.63%~3.13%。表明不同虫态茶蚜对茶树叶片含氮量的需要存在差异,其结果可为茶园合理施肥以及控制蚜虫危害提供依据。  相似文献   
8.
保水剂对煤矸石基质上高羊茅生长及营养吸收的影响   总被引:2,自引:0,他引:2  
赵陟峰  王冬梅  赵廷宁 《生态学报》2013,33(16):5101-5108
为探索保水剂对煤矸石废弃地上高羊茅生长及营养特征的影响,按煤矸石与土壤质量比设3种基质梯度,每种基质分别添加3种质量的保水剂,设对照(CK),共10种处理。观测和分析不同处理下高羊茅的生长高度、生物量、营养特征及SPAD值(相对叶绿素含量),结果显示:保水剂主要影响高羊茅地上部分的生物量,而煤矸石与土壤的质量比主要影响地下部分的生物量;煤矸石与土壤质量比相同条件下,添加1 g/kg的保水剂即可促进高羊茅的生长,添加2 g/kg保水剂能使高羊茅尽快适应基质环境,使其日均生长率在出苗后第2周达到峰值。煤矸石基质中添加保水剂能促使高羊茅将煤矸石基质中的营养元素从植株地下部分向地上部分转移,供植株生长需要,基质中添加1 g/kg保水剂时高羊茅对磷的吸收效果最好。此外,添加保水剂能使叶片的SPAD值增加。综合比较不同处理下高羊茅的株高、生物量、营养特征及叶片的SPAD值认为,处理6(煤矸石与土壤质量比为750:250、基质中添加2 g保水剂)与处理8(煤矸石与土壤质量比为500:500、基质中添加1 g保水剂)是适合煤矸石废弃地上高羊茅生长的较好配比。  相似文献   
9.
Aluminium (Al) phytotoxicity is an important soil constraint that limits crop yield. The objectives of this study were to investigate how growth, physiology, nutrient content and organic acid concentration is affected by Al, and to assess the degree of Al tolerance in different oil palm progeny (OPP). Four OPPs ['A' (Angola dura × Angola dura), 'B' (Nigerian dura × Nigerian dura), 'C' (Deli dura × AVROS pisifera) and 'D' (Deli dura × Dumpy AVROS pisifera)] were grown in different Al concentrations (0, 100 and 200 μm) in aerated Hoagland solution, pH 4.4, for 80 days. We observed a severe reduction (57.5%) in shoot dry weight, and root tips were reduced by 46.5% in 200 μm Al. In 'B' and 'C', the majority of macro- and micronutrients in plants were reduced significantly by 200 μm Al, with Mg being lowered by more than 50% in roots and shoots. The 200 μm Al treatment resulted in a 56.50% reduction in total leaf area, a 20% reduction in net photosynthesis and a 17% reduction in SPAD chlorophyll value in the third leaf. Root tips (0-5 mm) showed a significant increase in oxalic acid content with increasing Al concentration (~ 5.86-fold); progeny 'A' had the highest concentration of oxalic acid. There was a significant interaction between Al concentration × OPP on total leaf number, root volume, lateral root length, Mg and K in root and shoot tissues, and Ca and N in shoots. The OPPs could be ranked in their tolerance to Al as: 'A' > 'D' > 'B' > 'C'.  相似文献   
10.
This study quantified stomatal conductance in a CO2-fertilized warm-temperate forest. The study considered five items: (1) the characteristics of the diurnal and seasonal variation, (2) simultaneous measurements of canopy-scale fluxes of heat and CO2 and the normalized difference vegetation index (NDVI), (3) the stomatal conductance of sunlit and shaded leaves, (4) a stomatal conductance model, and (5) the effects of leaf age on stomatal conductance. Sampled plants included evergreen and deciduous species. Stomatal conductance, SPAD, and leaf nitrogen content were measured between March and December 2001. Sunlit leaves had the largest diurnal and seasonal variation in conductance in terms of both magnitude and variability. In contrast, shaded leaves had only low conductance and slight variation. Stomatal conductance increased sharply in new shooting leaves of Quercus serrata until reaching a maximum 2 months after full leaf expansion. The seasonal changes in the canopy-scale heat and CO2 fluxes were similar to the change in the canopy-scale NDVI of the upper-canopy plants. These seasonal changes were correlated with the leaf-level H2O/CO2 exchanges of upper-canopy plants, although these did not represent the stomatal conductance in fall completely. Seasonal variations in the leaf nitrogen content and SPAD were similar, except leaf foliation, until day 130 of the year, when the behaviors were completely the opposite. A Jarvis-type model was used to estimate the stomatal conductance. We modified it to include SPAD as a measure of leaf age. The seasonal variation in stomatal conductance was not as sensitive to SPAD, although estimates for evergreen species showed improvements.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号