基于上部叶片SPAD值估算小麦氮营养指数

快速、准确的监测诊断小麦氮营养状态对于评价小麦长势、指导氮肥运筹并预测籽粒产量均具有重要的意义.基于2009-2011年的大田试验,系统分析了小麦上部4张单叶不同叶位的SPAD值和归一化SPAD指数(NDSPADij)与氮营养指数的定量关系,通过简单分组线性回归筛选出在不同年际和不同品种间表现稳定的氮营养指数(NNI)定量方程.结果表明,小麦上部不同叶位SPAD值和NNI随施氮量提高而提高,而NDSPADij随施氮量的提高而降低.小麦单叶SPAD值与NNI的关系呈显著正相关,但这种关系在品种或年份之间不稳定,对小麦氮素诊断存在风险;除NDSPAD12外,NDSPADij与NNI之间呈显著负相关,经简单分组线性分析发现NDSPAD14与NNI之间在年份和品种之间表现最稳定,能够较好的定量估算氮营养指数,从而快速诊断小麦氮素是否亏缺.     

Molecular mapping of stomatal‐conductance‐related traits in durum wheat (Triticum turgidum ssp. durum)

The most promising traits identified in wheat to raise yield potential via an increase in biomass accumulation are stomatal conductance and stomatal‐conductance‐related traits, such as carbon isotope discrimination (CID) and photosynthetic rate. The evaluation of the extent of genetic variation and the mapping of chromosomal regions controlling these traits are essential for the development of effective breeding strategies in durum wheat. A population of 161 F2‐derived, F8–F9 recombinant inbred lines obtained from a cross between durum wheat (Triticum turgidum ssp. durum) cultivars Ofanto and Cappelli was phenotyped for heading date, plant height, leaf porosity, CID and chlorophyll concentration (estimated through the SPAD index) for 2007/2008 and 2008/2009 seasons, at Ottava, Sardinia (Italy) under irrigated conditions. The genotype mean heritability for leaf porosity, CID and chlorophyll concentration was moderate in size. Six quantitative trait loci were detected for leaf porosity, four for chlorophyll concentration, but only one for CID, because of the small variation expressed in the population for this trait under these experimental conditions. The quantitative trait loci for leaf porosity located on chromosome 3B appear to be more stable with respect to the others, and different microsatellite markers are positioned within the interval of the quantitative trait loci, or in their vicinity, that represent useful tools in programmes for selection assisted by molecular markers.     

Mild ammonium stress increases chlorophyll content in Arabidopsis thaliana

Nitrate (NO₃⁻) and ammonium (NH₄⁺) are the main forms of nitrogen available in the soil for plants. Excessive NH₄⁺ accumulation in tissues is toxic for plants and exclusive NH₄⁺-based nutrition enhances this effect. Ammonium toxicity syndrome commonly includes growth impairment, ion imbalance and chlorosis among others. In this work, we observed high intraspecific variability in chlorophyll content in 47 Arabidopsis thaliana natural accessions grown under 1 mM NH₄⁺ or 1 mM NO₃⁻ as N-source. Interestingly, chlorophyll content increased in every accession upon ammonium nutrition. Moreover, this increase was independent of ammonium tolerance capacity. Thus, chlorosis seems to be an exclusive effect of severe ammonium toxicity while mild ammonium stress induces chlorophyll accumulation.     

Soybean leaf nitrogen,chlorophyll content,and chlorophyll <Emphasis Type="Italic">a/b</Emphasis> ratio

The objective of this study was to assess genotypic variation in soybean chlorophyll (Chl) content and composition, and to test if these data could be used as a rapid screening method to predict genotypic variation in leaf tissue N content. Chl contents and composition were examined among 833 soybean (Glycine max L. Merr.) accessions and related to SPAD meter readings and leaf N content. In the initial year of the study (2002), the relationship between leaf Chl and leaf N contents (r ² = 0.043) was not sufficiently close for Chl to be useful as a predictive tool for leaf N content. Therefore, leaf N content was not determined in 2004 but samples were again collected for determination of Chl content and composition. In 2002, the soybean accessions separated into two distinct groups according to leaf Chl a/b ratios, with the majority of a mean ratio of 3.79. However, approximately 7 % (60) of the genotypes could be readily assigned to a group with a mean Chl a/b ratio of 2.67. Chl a/b analyses in 2004 confirmed the results obtained in 2002 and of 202 genotypes, all but 6 fell into the same group as in 2002.     

烟蚜为害特征的高光谱比较

利用手持式高光谱仪测定不同蚜量为害后烟草冠层光谱反射率的变化,同时使用叶绿素计测量叶绿素含量。结果表明,烟草光谱呈现标准植被光谱曲线,烟蚜Myzuspersicae(Sulzer)为害造成烟草光谱反射率下降,近红外波段反射率下降更为明显。和健康烟株相比,轻度(单株顶尖和上部5片叶蚜量≤15头)、中度(15头<单株顶尖和上部5片叶蚜量≤50头)、重度(单株顶尖和上部5片叶蚜量>50头)危害在绿光波段反射率分别下降12%,27%,52%,在近红外波段分别下降15%,20%,38%。对反射率曲线进行微分分析,健康烟株、轻度、中度和重度为害后的一阶导数最大值分别为0.031,0.022,0.026和0.019,其值随着蚜量增加而下降,对应的波长重度为害为718.45nm,其它为716.91nm,红边位置向长波方向移动1.46nm。蓝光、绿光、红光和近红外4个波段反射率和叶绿素含量SPAD值存在良好的线性回归关系,相关系数都达到极显著,绿光波段反射率对叶绿素含量的回归关系尤为显著;同时SPAD值越大,光谱反射率越高。该研究对于应用遥感技术大面积监测烟草生产中病虫害的发生,确定防治适期以及适宜的防治措施具有重要的应用前景。     

5种红树林植物叶片SPAD值比较

以5种红树林植物为研究材料,分析测试其叶片相对叶绿素含量(SPAD值),并比较红树林树种、样区对其叶片SPAD值的影响。结果表明,各样区、各树种以及单株之间SPAD值均存差异,对不同样区进行多重比较,可将其分为7类,5个红树林树种在叶绿素含量上差异较明显。各树种中以秋茄Kandelia obvolata最大(70.4),其次是红海榄Rhizophora stylosa (65.9)和木榄Bruguiera gymnorrhiza (62.9),白骨壤Avicennia marina为51.9,最小为桐花树Aegiceras corniculatum(48.6),树种平均为60.5。试验分析表明,树种因子效应极显著(P<0.01),强于样区因子效应,说明红树林树种是影响其叶片SPAD值的重要因子,同时也表明不同的立地环境条件对叶绿素含量存在影响。5种红树林植物叶片SPAD值均与其树高、基径生长性状存在显著正相关。     

Relationships between optically assessed polyphenols and chlorophyll contents,and leaf mass per area ratio in woody plants: a signature of the carbon–nitrogen balance within leaves?

Chlorophyll (Chl) and epidermal polyphenol (EPhen) contents were estimated in vivo using two optical leaf-clips, SPAD-502 and Dualex, respectively. The area-based measurements were transformed into mass-based data by taking into account the leaf dry mass per area (LMA). Measurements were performed on forest trees and on saplings grown under controlled conditions. While LMA increased with irradiance along a vertical transect in a beech canopy or in saplings grown under different and increasing irradiance levels, mass-based EPhen (EPhen(m)) increased, whereas mass-based Chl (Chl(m)) decreased. This was a signature of a gradual switch of investment from protein into polyphenol production. A similar signature was obtained in saplings grown on nitrogen-deficient soil with respect to fertilized controls. However, nitrogen effects remained moderate compared to irradiance-induced effects. EPhen(m) and Chl(m) both declined with plant ageing-induced increases in LMA, under all tested growth conditions. This was a signature of an accumulation of dry matter that diluted Chl and EPhen. The described competition between Chl and EPhen in leaves fits well with the predictions of the Protein Competition Model (PCM), that is, that the total leaf mass-based polyphenols content (Phen(t)) is controlled by the competition between protein and polyphenol biosynthetic pathways and its metabolic regulation.     

Evaluating the relationship between leaf chlorophyll concentration and SPAD-502 chlorophyll meter readings

Relationships between chlorophyll concentration ([chl]) and SPAD values were determined for birch, wheat, and potato. For all three species, the relationships were non-linear with an increasing slope with increasing SPAD. The relationships for birch and wheat were strong (r ² ∼ 0.9), while the potato relationship was comparatively weak (r ² ∼ 0.5). Birch and wheat had very similar relationships when the chlorophyll concentration was expressed per unit leaf area, but diverged when it was expressed per unit fresh weight. Furthermore, wheat showed similar SPAD–[chl] relationships for two different cultivars and during two different growing seasons. The curvilinear shape of the SPAD–[chl] relationships agreed well with the simulated effects of non-uniform chlorophyll distribution across the leaf surface and multiple scattering, causing deviations from linearity in the high and low SPAD range, respectively. The effect of non-uniformly distributed chlorophyll is likely to be more important in explaining the non-linearity in the empirical relationships, since the effect of scattering was predicted to be comparatively weak. The simulations were based on the algorithm for the calculation of SPAD-502 output values. We suggest that SPAD calibration curves should generally be parameterised as non-linear equations, and we hope that the relationships between [chl] and SPAD and the simulations of the present study can facilitate the interpretation of chlorophyll meter calibrations in relation to optical properties of leaves in future studies.     

Relationships between early vigour, grain yield, leaf structure and stable isotope composition in field grown barley

Fast growth and early development in barley are used in breeding programmes to improve the water use efficiency and transpiration efficiency of this crop in Mediterranean conditions. Here, we examine the use of several simple traits based on the structure and stable isotope composition of seedling leaves to assess differences in early vigour, phenology and grain yield, and also the interaction with low temperatures in barley. A set of 260 F₈ lines of two-row barley (Hordeum vulgare L.) derived from the cross of Tadmor and WI 2291 were cultivated in two locations in northwest Syria. Total chlorophyll content on an area basis (SPAD) and specific leaf dry weight (SLDW) were measured in recently fully expanded intact leaves of seedlings. Total leaf area and total dry weight per seedling were evaluated in the same seedlings. The stable isotope compositions of carbon and nitrogen (δ¹³C and δ¹⁵N, respectively) were analyzed in the same leaves on a subset of 75 genotypes. Number of days from planting to heading and grain yield were recorded at both sites. The grain yield measured at both locations was positively correlated with the SPAD value of seedlings, but showed no relationship with SLDW. Days to heading was negatively correlated with SPAD values. Regarding early vigour, a negative relationship between the SLDW and the total leaf area of seedlings was observed. However, no relationship between the δ¹³C of seedlings and early vigour was observed, except when only the genotypes most resistant to low temperatures (i.e. showing the highest SPAD values) were considered. This subset of genotypes showed negative relationships between δ¹³C and either total leaf area or total dry weight. In addition, δ¹⁵N was negatively correlated with SPAD only within the high-SPAD genotypes. This suggests that within the genotypes resistant to low temperatures, those with higher chlorophyll content assimilate more nitrogen from nitrate.     

甘南高寒草甸植物元素含量与土壤因子对坡向梯度的响应

通过测定甘南高寒草甸不同坡向条件下25科86种植物叶片氮(N)、磷(P)、钾(K)含量、有机碳(C)含量、叶片含水量和相对叶绿素(SPAD)值,以及不同坡向的土壤含水量、有机碳、全氮、全磷含量等土壤指标,分析了不同坡向植物叶片元素含量与土壤环境因子之间的关系。研究结果表明,在南坡-北坡梯度上,随着土壤含水量的增加,植物叶片P含量、叶K含量和叶片含水量显著增加,而相对叶绿素显著降低。土壤养分含量与植物叶片P、叶K含量和叶含水量显著正相关,与叶片相对叶绿素显著负相关。说明不同坡向条件下叶片养分含量受土壤因子的影响显著,土壤的水分及养分状况对植物叶片元素含量的贡献不同。土壤含水量是坡向梯度上影响植物叶片特征的最主要因子。坡向梯度上土壤含水量对植物叶片各种元素含量的影响和植物叶片含水量对不同土壤因子的响应模式支持了生长在南坡的植物能以提高水分和养分利用效率而适应南坡较为干旱和贫瘠的生境。