Degree of shade tolerance shapes seasonality of chlorophyll, nitrogen and phosphorus levels of trees and herbs in a temperate deciduous forest

Forest productivity is closely linked to seasonal variations and vertical differentiation in leaf traits.However,leaf structural and chemical traits variation among co-existing species,and plant functional types within the canopy are poorly quantified.In this study,the seasonality of leaf chlorophyll,nitrogen(N),and phosphorus(P)were quantified vertically along the canopy of four major tree species and two types of herbs in a temperate deciduous forest.The role of shade tolerance in shaping the seasonal variation and vertical differentiation was examined.During the entire season,chlorophyll content showed a distinct asymmetric unimodal pattern for all species,with greater chlorophyll levels in autumn than in spring,and the timing of peak chlorophyll per leaf area gradually decreased as shade tolerance increased.Chlorophyll a:b ratios gradually decreased with increasing shade tolerance.Leaf N and P contents sharply declined during leaf expansion,remained steady in the mature stage and decreased again during leaf senescence.Over the seasons,the lower canopy layer had significantly higher chlorophyll per leaf mass but not chlorophyll per leaf area than the upper canopy layer regardless of degree of shade tolerance.However,N and P per leaf area of intermediate shade-tolerant and fully shade-tolerant tree species were significantly higher in the upper canopy than in the lower.Seasonal variations in N:P ratios suggest changes in N or P limitation.These findings indicate that shade tolerance is a key feature shaping inter-specific differences in leaf chlorophyll,N,and P contents as well as their seasonality in temperate deciduous forests,which have significant implications for modeling leaf photosynthesis and ecosystem production.

Quantifying foliar trait variation and covariation in sun and shade leaves using leaf spectroscopy in eastern North America

Characterizing foliar trait variation in sun and shade leaves can provide insights into inter-and intra-species resource use strategies and plant response to environmental change.However,datasets with records of multiple foliar traits from the same individual and including shade leaves are sparse,which limits our ability to investigate trait-trait,trait-environment relationships and trait coordination in both sun and shade leaves.We presented a comprehensive dataset of 15 foliar traits from sun and shade leaves sampled with leaf spectroscopy,including 424 individuals of 110 plant species from 19 sites across eastern North America.We investigated trait variation,covariation,scaling relationships with leaf mass,and the effects of environment,canopy position,and taxonomy on trait expression.Generally,sun leaves had higher leaf mass per area,nonstructural carbohydrates and total phenolics,lower mass-based chlorophyll a+b,carotenoids,phosphorus,and potassium,but exhibited species-specific characteristics.Covariation between sun and shade leaf traits,and trait-environment relationships were overall consistent across species.The main dimensions of foliar trait variation in seed plants were revealed including leaf economics traits,photosynthetic pigments,defense,and structural traits.Taxonomy and canopy position collectively explained most of the foliar trait variation.This study highlights the importance of including intra-individual and intra-specific trait variation to improve our understanding of ecosystem functions.Our findings have implications for efficient field sampling,and trait mapping with remote sensing.

X-Rite’s ShadeVision System与Vitapan Classical比色板的匹配性分析

目的X-Rite’sShadeVision System和Vitapan Classical比色板的匹配性。方法采用X-Rite’sShadeVision System对Vitapan Classical比色板进行测色。结果X-Rite’s ShadeVision System测量结果排序与原排序一致,排列差异最大有6个色片的差距。相邻比色板的色差ΔEab参差不齐,最大的色差6.92,而最小的色差只有1.21。结论X-Rite’s ShadeVision System与Vitapan Classical比色板不完全匹配。

不同角度对X-Rite’s Shade Vision系统测量结果的影响

目的观察不同角度对X-Rite’s ShadeVision系统测量比色板结果的影响。方法将一副新的Vita16色比色板固定在粉红色的蜡中。X-Rite’s ShadeVision系统分别在平行于比色板唇面,5°、10°、15°向左右侧和切向、龈向倾斜时测量颜色,以L*,a*,b*及Vita16色比色板色片颜色表示测量结果。计算ΔL,Δa,Δb和ΔE*ab,数据用单因素方差分析。结果向右倾斜5°、10°、15°时L*值分别减少0.22,0.97和0.93,而向左倾斜L*增加;垂直向角度改变时,L*值增加;最大的ΔL值在向龈向倾斜15°(2.84)和向切向倾斜15°(2.37),这导致相应位置出现最大的ΔE*ab(3.22±0.37)和(2.50±0.63),15°向左和右倾斜时,ΔE*ab分别为1.87±0.59和1.20±0.25。与其他位置比较,向龈向和切向15°时,ΔE*ab明显高(P<0.05)。结论X-Rite’sShadeVision测量时,正确的测量位置对获得准确的测量结果非常重要,角度的偏移,尤其是垂直向的倾斜会影响测量结果。

A study on the shade tolerance of Muehlewbeckia complera

Muehlewbeckia complera was introduced to China in 2002 as indoor-hanging ornamental foliage plant. The experiment of the shade tolerance for this species was carried out in different light intensities (0.14–946.00 μmol·m?2·s?1). After 40 days in experimental areas, leaf photosynthentic characteristics indexes ofM. complera in different photosynthesis active radiation (PAR) were measured with LI-COR6400 apparatus, such as the light compensation point, light saturation point, and maximum net photosynthesis rate, at the same time, the increments of total leaf area and leaf amount were measured. The results showed that the optimum light intensity range forM. complera was from 9.26 μmol·m?2·s?1 to 569.00 μmol·m?2·s?1 (463–28150 lx, relative humidity (RH) for 46–60%, temperature at 16–22°C). Under this condition, leaf photosynthetic efficiency was tiptop. AlthoughM. complera belonged to the moderate sun-adaptation plant species, the plant growth was inhibited when PAR increased to the level of 569.000 μmol·m?2·s?1 or above.M. complera could sprout new leaves in photosynthesis active radiation of 0.16–19.22 μmol·m?2·s?1 (8–961 lx), or 10 μmol·m?2·s?1 for above 6 h. Keywords Muehlewbeckia complera - Shade tolerance - Cultivation - Photosynthesis CLC number S602.1 Document code A Foundation item: This study was supported by the Research Foundation of Northeast Forestry University.Biography: YUE Hua (1962-), female, Associate professor in Northeast Forestry University, Harbin 150040, P. R. China.Responsible editor: Zhu Hong

SHADE协调机制在亚丁湾、索马里海域护航中的作用

"信息共享与防止冲突"(简称SHADE)这一军事协调会议为国际社会开展多边合作实施海上护航提供了平台。通过梳理SHADE协调机制产生的背景及运作方式,并以第14次工作会议为例,分析了SHADE这一国际协调机制在打击索马里海盗、维护海上航行安全中的作用,同时指出了其存在的不足。

由国际会议SHADE反思海军护航英语教学

"信息共享与防止冲突"(Shared Awareness and De-confliction)这一军事协调会议为国际社会开展多边合作打击索马里海盗提供了平台。通过分析会议期间所采集的语言素材,并结合护航协调人员英语培训班的教学实践,提出护航英语教学的新思路。

在VC++中使用VertexShader实现卡通渲染

介绍了Cell-shade(r卡通渲染)和VertexShader技术,论述了卡通渲染的原理,并给出了VertexShader的一些具体使用实例。

Photoinhibition in Shaded Cotton Leaves After Exposing to High Light and the Time Course of Its Restoration

Chlorophyll fluorescence emission, pigment composition and photosynthetic rate of shade-grown cotton ( Gossypium hirsutum L.) plants were measured immediately after suddenly exposing to full sunlight and at regular intervals there after within 15 d. Photoinhibition occurred in shade-grown cotton leaves immediately after exposed to full sunlight. The chlorophyll fluorescence parameter F-v/F-m and PhiPS II, which reflect the efficiency of PS II,obviously decreased in shade-grown leaves, much lower than that of the full sunlight-grown leaves. On the contrary, F-o value was sharply increased. Neither of these parameters could completely recover till next morning. The photoinhibition was chronic and continued for about 4 d, while the F-v/F-m and the net photosynthetic rate ( P-n) continued to decline, then began to increase gradually 6 d later and turned stable after 10 - 12 d, appearing as an acclimation phenomenon. However, the final value of F-v/F-m and P-n did not reach the level as in those leaves grown in the full sunlight ever before. The final P-n was higher by 60% than that before exposure, but lower for more than 40% than that of the full sunlight-grown leaves. The most notable response of chloroplast pigment composition was a pronounced increase in the pool size of carotenoids in xanthophyll cycle over a period of 3 d. The results indicated that when shade-grown cotton seedlings were suddenly transferred to the full sunlight, the decline of F-v/F-m and P-n might associate with the damage of the PS II reaction center. During the light acclimation, photoprotective mechanisms such as the xanthophyll cycle-dependent energy dissipation were increased, so that photodamage in leaves transferred from low to high light might be reduced.

Shadepilot全牙比色仪测定牙龈色对比色板色标颜色的影响

目的:通过体外模拟实验评价牙龈比色板在临床比色中的意义。方法:使用分光光度计型全牙比色仪Shadepilot测量42个比色板色标在4种牙龈比色板(Gumy1,2,3,4)衬托下颈、中、切3部分色彩参数(CIE1976L*a*b*),使用比色仪内置软件计算有无牙龈比色板衬托的色标相同位置的色差值(△E),分析牙龈色对色标颜色的影响。结果:42个色标在4种牙龈色衬托下与无牙龈色衬托的色差值为:颈部(2.93±0.79)NBS,中部(0.51±0.27)NBS,切端(0.61±0.29)NBS;Gumy-1、2、3、4组牙龈色对色标颈、中、切三部分的影响组间差异无显著性(P>0.05)。结论:在模拟测量条件下,牙龈色对比色板色标颈部有影响,肉眼可识别,对色标中部及切端无影响;4种模拟牙龈颜色对比色板色标颜色的影响无统计学差异。

Shade stress decreases stem strength of soybean through restraining lignin biosynthesis

Lodging is the most important constraint for soybean growth at seedling stage in maize-soybean relay strip intercropping system.In the field experiments,three soybean cultivars Nandou 032-4(shade susceptible cultivar; B1),Jiuyuehuang(moderately shade tolerant cultivar; B2),and Nandou 12(shade tolerant cultivar; B3) were used to evaluate the relationship between stem stress and lignin metabolism in the stem of soybean.Results showed that the intercropped soybean was in variable light condition throughout the day time and co-growth stage with maize.The xylem area and cross section ratio played a main role to form the stem stress.The B3 both in intercropping and monocropping expressed a high stem stress with higher xylem area,lignin content,and activity of enzymes(phenylalanine ammonia-lyase(PAL),4-coumarate: CoA ligase(4CL),cinnamyl alcohol dehydrogenase(CAD),and peroxidase(POD)) than those of B1 and B2.Among the soybean cultivars and planting pattern,lignin content was positively correlated with stem stress.However,a negative correlation was found between lignin content and actual rate of lodging.In conclusion,the shade tolerant soybean cultivar had larger xylem area,higher lignin content and activities of CAD,4CL,PAL,and POD than other soybean cultivars in intercropping.The lodging in maize-soybean intercropping can be minimized by planting shade tolerant and lodging resistant cultivar of soybean.The lignin content in stem could be a useful indicator for the evaluation of lodging resistance of soybean in intercropping and activities of enzymes were the key factors that influence the lignin biosynthesis.

The molecular mechanism of shade avoidance in crops--How data from Arabidopsis can help to identify targets for increasing yield and biomass production

In order to prevent or counteract shading,plants enact a complex set of growth and developmental adaptations when they sense a change in light quality caused by other plants in their vicinity.This shade avoidance response（SAR）typically includes increased stem elongation at the expense of plant fitness and yield,making it an undesirable trait in an agricultural context.Manipulating the molecular factors involved in SAR can potentially improve productivity by increasing tolerance to higher planting density.However,most of the investigations of the molecular mechanism of SAR have been carried out in Arabidopsis thaliana,and it is presently unclear in how far results of these investigations apply to crop plants.In this review,current data on SAR in crop plants,especially from members of the Solanaceae and Poaceae families,are integrated with data from Arabidopsis,in order to identify the most promising targets for biotechnological approaches.Phytochromes,which detect the change in light caused by neighboring plants,and early signaling components can be targeted to increase plant productivity.However,they control various photomorphogenic processes not necessarily related to shade avoidance.Transcription factors involved in SAR signaling could be better targets to specifically enhance or suppress SAR.Knowledge integration from Arabidopsis and crop plants also indicates factors that could facilitate the control of specific aspects of SAR.Candidates are provided for the regulation of plant architecture,flowering induction and carbohydrate allocation.Yet to-be-elucidated factors that control SAR-dependent changes in biotic resistance and cell wall composition are pointed out.This review also includes an analysis of publicly available gene expression data for maize to augment the sparse molecular data available for this important species.

Shade adaptive response and yield analysis of different soybean genotypes in relay intercropping systems

Soybean is one of the major oil seed crops,which is usually intercropped with other crops to increase soybean production area and yield.However,soybean is highly sensitive to shading.It is unclear if soybean morphology responds to shading（i.e.,shade tolerance or avoidance）and which features may be suitable as screening materials in relay strip intercropping.Therefore,in this study,various agronomic characteristics of different soybean genotypes were analyzed under relay intercropping conditions.The soybean materials used in this study exhibited genetic diversity,and the coefficient of variations of the agronomic parameters ranged from 13.84 to 72.08%during the shade period and from 6.44 to 52.49%during the maturity period.The ratios of shading to full irradiance in stem mass fraction（SMF）were almost greater than 1,whereas opposite results were found in the leaves.Compared with full irradiance,the average stem length（SL）,leaf area ratio（LAR）and specific leaf area（SLA）for the two years（2013 and 2014）increased by 0.78,0.47 and 0.65 under shady conditions,respectively.However,the stem diameter（SD）,total biomass（TB）,leaf area（LA）,number of nodes（NN）on the main stem,and number of branches（BN）all decreased.During the shady period,the SL and SMF exhibited a significant negative correlation with yield,and the SD exhibited a significant positive correlation with yield.The correlation between the soybean yield and agronomic parameters during the mature period,except for SL,the first pod height（FPH）,100-seed weight（100-SW）,and reproductive growth period（RGP）,were significant（P〈0.01）,especially for seed weight per branch（SWB）,pods per plant（PP）,BN,and vegetative growth period（VGP）.These results provide an insight into screening the shade tolerance of soybean varieties and can be useful in targeted breeding programs of relay intercropped soybeans.

Effect of shade stress on lignin biosynthesis in soybean stems

To clarify how shade stress affects lignin biosynthesis in soybean stem, two varieties, Nandou 12（shade tolerant） and Nan 032-4（shade susceptible） grew under normal light and shade conditions（the photosynthetically active radiation and the ratio of red：far-red were lower than normal light condition）. Lignin accumulation, transcripts of genes involved in lignin biosynthesis, and intermediates content of lignin biosynthesis were analyzed. Both soybean varieties suffered shade stress had increased plant heights and internode lengths, and reduced stem diameters and lignin accumulation in stems. The expression levels of lignin-related genes were significantly influenced by shade stress, with interactions between the light environment and variety. The gene of 3-hydroxylase（C3H）, cinnamoyl-Co A reductase（CCR）, caffeoylCoAO-methyltransferase（CCoAOMT）, and peroxidase（POD） attributed to lignin biosynthesis under shade stress, and the down-regulation of these genes resulted in lower caffeic, sinapic, and ferulic acid levels, which caused a further decrease in lignin biosynthesis. Under shade stress, the shade tolerant soybean variety（Nandou 12） showed stiffer stems, higher lignin content, and greater gene expression level and higher metabolite contents than shade susceptible one. So these characteristics could be used for screening the shade-tolerant soybean for intercropping.

CONTRACTED EFFECT OF BELL-SHADE SHAPE WELDING ARC AND ACCOMPANIED MAGNETIC FIELD WITH SPIRAL PIPE SHAPE

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Interactive effect of shade and PEG-induced osmotic stress on physiological responses of soybean seedlings

Intensively farmed crops used to experience numerous environmental stresses.Among these,shade and drought significantly influence the morpho-physiological and biochemical attributes of plants.However,the interactive effect of shade and drought on the growth and development of soybean under dense cropping systems has not been reported yet.This study investigated the interactive effect of PEG-induced osmotic stress and shade on soybean seedlings.The soybean cultivar viz.,C-103 was subjected to PEG-induced osmotic stress from polyethylene glycol 6000(PEG-6000)under shading and non-shading conditions.PEG-induced osmotic stress significantly reduced the relative water contents,morphological parameters,carbohydrates and chlorophyll contents under both light environments.A significant increase was observed in osmoprotectants,reactive oxygen species and antioxidant enzymes in soybean seedlings.Henceforth,the findings revealed that,seedlings grown under non-shading conditions produced more malondialdehyde and hydrogen peroxide contents as compared to the shade-treated plants when subjected to PEG-induced osmotic stress.Likewise,the shaded plants accumulated more sugars and proline than non-shaded ones under drought stress.Moreover,it was found that nonshaded grown plants were more sensitive to PEG-induced osmotic stress than those exposed to shading conditions,which suggested that shade could boost the protective mechanisms against osmotic stress or at least would not exaggerate the adverse effects of PEG-induced osmotic stress in soybean seedlings.

Creation of two hyperactive variants of phytochrome B1 for attenuating shade avoidance syndrome in maize

Increasing the planting density of maize is an effective measure to improve its yield.However,plants under high planting density tend to trigger shade avoidance syndrome(SAS),reducing lodging resistance and ultimately yield drop.Phytochrome B(phyB)plays a dominant role in mediating shade avoidance response.This study constructed two hyperactive mutated alleles of maize PHYB1:ZmPHYB1^(Y98F)(mimicking Y104F of AtPHYB)and ZmPHYB1^(Y359F)(mimicking Y361F of AtPHYB).Ectopic expression of ZmPHYB1^(Y98F) and ZmPHYB1^(Y359F) under the control of the ZmPHYB1 promoter in the Arabidopsis phyB-9 background rendered enhanced activity on complementing the phyB-9 related phenotypes compared with ZmPHYB1^(WT).Moreover,similar to the behavior of ZmPHYB1^(WT),ZmPHYB1Y98F and ZmPHYB1^(Y359F) proteins are localized to the nucleus after red light exposure,and could interact with PIF proteins of maize.In addition,expression of ZmPHYB1^(Y98F) and ZmPHYB1^(Y359F) variants under the control of the native ZmPHYB1 promoter attenuated SAS of maize seedlings subjected to simulated shade treatment.It effectively reduced mature maize’s plant height and ear height in field conditions.The results combined demonstrate the utility of ZmPHYB1^(Y98F) and ZmPHYB1^(Y359F) for attenuating SAS and breeding high density-tolerant varieties of maize.

共享数据工程(SHADE)体系结构及实现描述

文章在深入研究DIICOE的基础上,描述了DIICOE中共享数据工程(SHADE)的体系结构及实现方式。

Growth and Photosynthesis Responses of a Super Dwarf Rice Genotype to Shade and Nitrogen Supply

Specific aspects of plant cultivation require tests under fully controlled environmentalconditions with restricted energy supply, such as orbit-based space laboratories and low-light conditions.For these growing conditions, super dwarf plants have been developed as model crops, and a gibberellindeficientSuper Dwarf Rice genotype was proposed as a model crop for space flight plant experiments.We tested this genotype in a climate chamber experiment under different illumination and nitrogen supplylevels to assess its suitability under scenarios with limited resource availability. A 25% reduction inillumination led to a 75% reduction in yield, mainly due to a 60% reduction in formed tillers and 20%reduction in grain weight, and a 80% reduction in illumination caused total yield loss. Leaf area underreduced illumination was significantly lower, and only marginal changes in the dimensions of leaves wereobserved. Plant photosynthesis was not significantly different between control and 75% illumination. Thiswas explained by a higher photochemical efficiency under lower light conditions and a reduced mesophyllresistance. Therefore, we concluded that this genotype is well-suited for plant experiments under spaceand light-limited conditions since it kept its small stature and showed no shade avoidance mechanisms,such as leaf elongation, which would complicate experiments under low-light conditions. Nitrogenconcentrations of 2.8 and 1.4 mmol/L led to no differences in plant growth. We concluded that a nitrogenconcentration of 1.4 mmol/L is sufficient for this genotype under the light intensities.

Weak stem under shade reveals the lignin reduction behavior

Shades caused by neighboring tall plants in intercropping systems and weak sunlight are constraints in yield optimization. Shade influences many aspects of plant growth and development, leading to weak stems and susceptibility to lodging. The plant cell wall is composed of certain proteins that allow the walls to stretch out, a process called cell wall loosening. Shade affects anatomical, morphological, and physiological traits of plants, thus reducing the physical strength of the stem in crops by changing the loosening of cell walls. Flexibility of cells facilitates further modifications such as wall loosening. In addition, shade stress causes increased internode length, and reduced xylem synthesis and photosynthesis. In shaded plants, lignin deposition in vascular bundles and sclerenchyma cells of stems is decreased. Lignin is a light sensitive phenolic compound and shading decreases the transcript abundance of several phenolic compound(flavone and lignin) related genes. Shading significantly influences the metabolic activities of phenylalanine ammonia-lyase(PAL), peroxidase(POD), 4-coumarate: CoA ligase(4 CL), and cinnamyl alcohol dehydrogenase(CAD) involved in lignin biosynthesis. Furthermore, suppression of lignin biosynthesis activities by abiotic stresses causes abnormal phenotypes such as collapsed xylem, bent stems, and growth retardation. In this review, the underlying mechanisms illustrate that under shading conditions reduced lignin content results in slender, weak, and unstable stems. The objective of this review is to elaborate lignin biosynthesis and its variability under stressful environmental conditions, especially in shade stress environments. The effects of shade on stem lignin metabolism are discussed on the morphogenetic, physiological, and proteomic levels.