Leaf shape and its relationship with Leaf Area Index in a sugar beet (<Emphasis Type="Italic">Beta vulgaris</Emphasis> L.) cultivar

Heteroblasty of sugar beet cultivar Rizor was studied under field conditions for three growing seasons (2003, 2005, 2006) in a Randomized Complete Block (RCB) design experiment. Eleven leaf samplings, from early June till the end of October, were conducted each year and leaf shape parameters [leaf area (LA), centroid X or Y (CX or CY), length (L), width (W), average radial (AR), elongation (EL), shape factor (SF)] were determined by an image analysis system. During samplings, Leaf Area Index (LAI) was measured non-destructively. Significant year and sampling effects were found for all traits determined. With the progress of the growing season, leaves became smaller (LA, L, W, and AR were decreased) and rounded. The largest leaves were sampled in 2006 when LAI was highest. LA was strongly correlated with L and W with simple functions (y = 0.1933 x^2.2238, r ² = 0.96, p<0.001, and y = 28.693 x − 192.33, r ² = 0.97, p< 0.001, respectively), which could be used for non-destructive LA determination. Also, LAI was significantly related with LA and leaf dimensions (L, W) suggesting that an easy, non-destructive determination of LAI under field conditions is feasible for sugar beet cv. Rizor. An erratum to this article is available at .     

Leaf area prediction model for sugar beet (<Emphasis Type="Italic">Beta vulgaris</Emphasis> L.) cultivars

In two successive years (2003 and 2004), a set of 16 commercial sugar beet cultivars was established in Randomized Complete Block experiments at two sites in central Greece. Cultivar combination was different between years, but not between sites. Leaf sampling took place once during the growing season and leaf area, LA [cm²], leaf midvein length, L [cm] and maximum leaf width, W [cm] were determined using an image analysis system. Leaf parameters were mainly affected by cultivars. Leaf dimensions and their squares (L², W²) did not provide an accurate model for LA predictions. Using L×W as an independent variable, a quadratic model (y = 0.003 x² − 1.3027 x + 296.84, r ² = 0.970, p<0.001, n = 32) provided the most accurate estimation of LA. With compromises in accuracy, the linear relationship between L×W and LA (y = 0.5083 x + 31.928, r ² = 0.948, p<0.001, n = 32) could be used as a prediction model thanks to its simplicity.     

Relationship between specific leaf area,leaf thickness,leaf water content and <Emphasis Type="Italic">SPAD-502</Emphasis> readings in six Amazonian tree species

The aim of this work was to assess the effect of leaf thickness, leaf succulence (L_S), specific leaf area (SLA), specific leaf mass (W_s) and leaf water content (LWC) on chlorophyll (Chl) meter values in six Amazonian tree species (Carapa guianensis, Ceiba pentandra, Cynometra spruceana, Pithecolobium inaequale, Scleronema micranthum and Swietenia macrophylla). We also tested the accuracy of a general calibration equation to convert Minolta Chl meter (SPAD-502) readings into absolute Chl content. On average, SPAD values (x) increased with fresh leaf thickness (FLT [μm] = 153.9 + 0.98 x, r ² = 0.06**), dry leaf thickness (DLT [μm] = 49.50 + 1.28 x, r ² = 0.16**), specific leaf mass (W_s [g (DM) m⁻²] = 6.73 + 1.31 x, r ² = 0.43**), and leaf succulence (L_S [g(FM)] m⁻² = 94.2 + 1.58 x, r ² = 0.19**). However, a negative relationship was found between SPAD values and either specific leaf area [SLA (m² kg⁻¹) = 35.1 − 0.37 x, r ² = 0.38**] or the leaf water content (LWC [%]= 80.0 − 0.42 x, r ² = 0.58**). Leaf Chl contents predicted by the general calibration equation significantly differed (p<0.01) from those estimated by species-specific calibration equations. We conclude that to improve the accuracy of the SPAD-502 leaf thickness and LWC should be taken into account when calibration equations are to be obtained to convert SPAD values into absolute Chl content.     

Leaf area estimation in a sugar beet cultivar by linear models

An indirect method of leaf area measurement for Rizor sugar beet cultivar was tested. Leaves were sampled during two growing seasons in a Randomised Complete Block Design experiment. For 2002 samplings, leaf area [cm²] was linearly correlated with maximum leaf width [cm] using all leaf samples (r ² = 0.83, p < 0.001) or using the means of the 8 sampling occasions (r ² = 0.97, p < 0.001). Correlations between leaf area and leaf mid vein length [cm] were weaker (r ² = 0.75, p < 0.001 and r ² = 0.93, p < 0. 001, respectively). For 2003 samplings, the area estimated by the equations was highly correlated to the measured leaf area.     

Long-time variations in leaf mass and area of Mediterranean evergreen broad-leaf and narrow-leaf maquis species

Morphological (dry mass, DM; surface area, LA; leaf mass per area, LMA), anatomical (leaf thickness, L), phenological (leaf life span, LL), and physiological (net photosynthetic rate, P _N) leaf traits of the evergreen species co-occurring in the Mediterranean maquis developing at Castelporziano (Rome) were tested. The correlation analysis indicated that LMA variation was tightly associated with LL variations: Cistus incanus and Arbutus unedo had a short LL (4±1, summer leaves, and 11±1 months, respectively) and low LMA (153±19 g m⁻²) values, Quercus ilex, Phillyrea latifolia, and Pistacia lentiscus high LMA (204±7 g m⁻²) and long LL (22±3 months), Erica arborea, Erica multiflora, and Rosmarinus officinalis a short LL (9±2 months) and an either high (213±29 g m⁻², R. officinalis and E. multiflora) or low (115±17 g m⁻², E. arborea) LMA. LMA values were significantly (p≤0.05) correlated with P _N (r≥0.68). In the tested species, LMA increased in response to the decrease of the total rainfall during the leaf expansion period. LMA variation was due to the unequal variation of DM and LA in the considered species. LMA is thus a good indicator of evergreen maquis species capability to respond to climate change, in particular to total rainfall decrease in the Mediterranean basin.     

胡杨叶功能性状特征及其对地下水埋深的响应

叶片性状反映了植物对环境的适应能力及其自我调控能力。以塔里木干旱荒漠区建群种胡杨（Populus euphratica）为研究对象,通过分析自然生长状况下胡杨叶功能性状对地下水埋深（GWD）的响应及功能性状间的权衡关系,揭示胡杨对极端干旱荒漠环境的生态适应策略。结果表明：胡杨7个叶功能性状种内变异程度不同（9.20%-40.02%）,叶面积（LA）变异程度最大,叶干物质含量（LDMC）与叶片含水量（LWC）变异程度较低,GWD梯度上表现出较大的分化变异特征。叶性状在不同GWD之间差异显著（P<0.05）,与GWD呈极显著相关（P<0.01）。比叶面积（SLA）、LA、LWC与叶干重（LDM）呈极显著正相关（P<0.01）,与叶厚度（LT）、叶组织密度（LTD）、LDMC呈极显著的负相关（P<0.01）;LDMC与LT、LTD,LWC与LA、SLA呈极显著正相关（P<0.01）,反映胡杨通过叶性状间的相互调节与权衡来适应干旱荒漠环境。逐步回归分析表明LA、LT对GWD变化最敏感,可间接借助这2个性状来预测干旱荒漠区地下水埋深变化。随GWD降低,胡杨SLA、LA、LDM、LWC减小,而LT、LTD、LDMC增大,其由高生长速率、资源利用能力的开拓型策略转变为以增强自身养分储存、防御能力的保守型策略,拓宽了生态幅和增强其在干旱逆境的适合度。可见,极端干旱荒漠区胡杨形成了小的LA、SLA、LDM,大的LT、LDMC、LTD等一系列有利于减少水分散失、储存养分和增强耐旱能力的干旱性状组合,这可能是其适应干旱贫瘠环境的生态策略。     

Contrasting leaf phenology of woody species of dry tropical forest

We studied selected leaf traits [leaf area (LA), leaf water content (LWC), leaf fresh weight (LFW), leaf dry weight (LDW), specific leaf area (SLA) and chlorophyll content] of eight woody species (Shorea robusta, Buchanania lanzan, Diospyros melanoxylon, Lagerstroemia parviflora, Lannea coromandelica, Terminalia tomentosa, Holarrhena antidysenterica and Lantana camara) dominant at four sites in a dry tropical deciduous forest over complete two annual cycles (2008–2010). Our results showed that leaf traits varied across species (1.7–11.5 fold), months (1.2–1.5 fold) and sites (1.1–1.3 fold). However, leaf traits showed smaller variation between sites than between species. Leaf lifespan varied from 7 months (L. coromandelica) to 12 months (S. robusta). On the same sites, species differed in the length of deciduous period. The maximum LA, LDW, LFW and LWC were recorded for the semi-evergreen species, SLA for long-deciduous species and chlorophyll content for short-deciduous species, respectively. The coefficient of variation was maximum for LDW and minimum for chlorophyll content. Among the eight woody species, T. tomentosa exhibited the greatest LA, LDW, LFW and LWC. LA, LWC, LFW, LDW, SLA, LD, SD, MD & SE confirm.     

Cold Tolerance of the Photosynthetic Apparatus: Pleiotropic Relationship between Photosynthetic Performance and Specific Leaf Area of Maize Seedlings

The objective of this study was to elucidate the genetic relationship between the specific leaf area (SLA) and the photosynthetic performance of maize (Zea mays L.) as dependent on growth temperature. Three sets of genotypes: (i) 19 S₅ inbred lines, divergently selected for high or low operating efficiency of photosystem II (Φ_PSII) at low temperature, (ii) a population of 226 F_2:3 families from the cross of ETH-DL3 × ETH-DH7, and (iii) a population of 168 F_2:4 families from the cross of Lo964 × Lo1016 were tested at low (15/13 °C day/night) or at optimal (25/22 °C day/night) temperature. The latter cross was originally developed to study QTLs for root traits. At 15/13 °C the groups of S₅ inbred lines selected for high or low Φ_PSII differed significantly for all the measured traits, while at optimal temperature the groups differed only with regard to leaf greenness (SPAD). At low temperature, the SLA of these inbred lines was negatively correlated with Φ_PSII (r = − 0.56, p < 0.05) and SPAD (r = − 0.80, p < 0.001). This negative relationship was confirmed by mapping quantitative trait loci (QTL) in the two mapping populations. A co-location of three QTLs for SLA with QTLs for photosynthesis-related traits was detected in both populations at 15/13 °C, while co-location was not detected at 25/22 °C. The co-selection of SLA and Φ_PSII in the inbred lines and the co-location of QTL for SLA, SPAD, and Φ_PSII at 15/13 °C in the QTL populations strongly supports pleiotropy. There was no evidence that selecting for high Φ_PSII at low temperature leads to a constitutively altered SLA.     

Nondestructive,simple, and accurate model for estimation of the individual leaf area of som (<Emphasis Type="Italic">Persea bombycina</Emphasis>)

Nondestructive approach of modeling leaf area could be useful for plant growth estimation especially when number of available plants is limited and/or experiment demands repeated estimation of leaf area over a time scale. A total of 1,280 leaves were selected randomly from eight different morphotypes of som (Persea bombycina) established at randomized complete block design under recommended cultural regimes in field. Maximum leaf laminar width (B), length (L) and their squares B², L²; leaf area (LA), and lamina length × width (L×B) were determined over two successive seasons. Leaf parameters were significantly affected by morphotypes; but seasons had nonsignificant impacts on tested features. Therefore, pooled seasonal morphotype means of each parameter were used to establish relationship with LA. L and its square L² did not provide accurate models for LA predictions. Considerably better models were obtained by using B (y = 2.984 + 7.9664 x, R ² = 0.615, P≥0.001, n = 119) and B² (y = 12.784+ 0.9604 x, R ² = 0.605, P≥0.001, n = 119) as independent variables. However, maximum accuracy of prediction of LA could be achieved through a simple linear relationship of L×B (y = 8.2203 + 0.4224 x, R ² = 0.843, P≥0.0001, n = 119). The model (LA:L×B) was validated with randomly selected leaf samples (n = 360) of som morphotypes and highly significant (P≤0.001) linear function was found between actual and predicted LAs. Therefore, the last model may consider adequate to predict leaf area of all cultivars of som with sufficient fidelity.     

What determines interspecific variation in relative growth rate of <Emphasis Type="Italic">Eucalyptus</Emphasis> seedlings?

The present study examines relative growth rate (RGR) and its determinants in seedlings of nine Eucalyptus species. Species were selected from mesic (1,800 mm a⁻¹ rainfall) through to semi-arid habitats (300 mm a⁻¹), and thus, notionally vary in “stress” tolerance. Seedlings were grown in a glasshouse during early summer and received between 33 mol and 41 mol PAR m⁻² day⁻¹ . The mean RGR varied among species—from a minimum of 66 mg g⁻¹ day⁻¹ in E. hypochlamydea to a maximum of 106 mg g⁻¹ day⁻¹ in E. delegatensis. RGR was positively related to rainfall at the sites of seed collection. Neither specific leaf area (SLA) nor net assimilation rate was related to rainfall or RGR. While the absence of relationships with SLA and net assimilation rate contrasts with other studies and species, we cannot rule out the effects of sample size (n=9 species) and modest ranges in SLA and RGR. The ratio of leaf mass to total mass (LMR) varied from 0.49±0.07 g g⁻¹ in E. socialis to 0.74±0.04 g g⁻¹ in E. delegatensis and was strongly positively related with rainfall (r ²=0.77). Interspecific differences in RGR were strongly related to LMR (positive relationship, r ²=0.50) and the rate of dry matter production per mol of leaf nitrogen (positive relationship, r ²=0.64). Hence, the slow RGR of low-rainfall species was functionally related to a lower growth rate per mol of leaf nitrogen than high-rainfall species. Furthermore, slow RGR of low-rainfall species was related to greater allocation to roots at the expense of leaves. Increasing allocation to roots versus leaves is likely an adaptation to soil and atmospheric water deficits, but one that comes at the expense of a slow RGR.     

Genotypic variation in drought response of silver birch (Betula pendula Roth): leaf and root morphology and carbon partitioning

This study investigates the drought response of four genotypes of Betula pendula with a focus on leaf and root morphological traits, leaf phenology and carbon partitioning between shoot and root. Potted one-year-old clonal plants of four genotypes from regions with low to high annual rainfall (550–1270 mm year⁻¹) were subjected to drought periods of 12–14 weeks in two subsequent years. Well-watered control plants of the four genotypes differed significantly with respect to total leaf area per plant (LA) and specific leaf area (SLA), whereas differences in total fine root surface area (RA), root specific area (SRA), and the fine root:leaf mass ratio (FR:LM) were not significant. Highest LA and SLA were found in the clone originating from the driest environment. In complementary physiological investigations this clone was found to have the highest water use as well which was interpreted as competitive superiority in terms of water consumption. Drought resulted in an increase in SLA in all genotypes, and a decrease in LA. Leaf area reduction was more pronounced in the genotypes from high than in those from low rainfall origin. The ratio of total root to leaf surfaces remained more or less constant after drought application despite an increase in FR:LM. This is explained by a decrease in SRA resulting from a reduced abundance of very small fine rootlets (diameter <0.2 mm) in the drought-treated plants. The loss in total root surface area due to a reduction in finest root mass was compensated for by a relative increase in total root dry mass per plant. Comparison of results from the first and second drought period indicated a marked influence of timing of drought, root system size, and putative root limitation on plant drought response. We conclude that leaf and root morphology, the total leaf and root surfaces, and the morphological response to drought in birch are to a large extent under genetic control.     

Leaf traits variation during leaf expansion in <Emphasis Type="Italic">Quercus ilex</Emphasis> L.

The morphological, anatomical and physiological variations of leaf traits were analysed during Quercus ilex L. leaf expansion. The leaf water content (LWC), leaf area relative growth rate (RGR_l) and leaf dry mass relative growth rate (RGR_m) were the highest (76±2 %, 0.413 cm² cm⁻² d⁻¹, 0.709 mg mg⁻¹ d⁻¹, respectively) at the beginning of the leaf expansion process (7 days after bud break). Leaf expansion lasted 84±2 days when air temperature ranged from 13.3±0.8 to 27.6±0.9 °C. The net photosynthetic rate (P _N), stomatal conductance (g _s), and chlorophyll content per fresh mass (Chl) increased during leaf expansion, having the highest values [12.62±1.64 μmol (CO₂) m⁻² s⁻¹, 0.090 mol (H₂O) m⁻² s⁻¹, and 1.03±0.08 mg g⁻¹, respectively] 56 days after bud break. Chl was directly correlated with leaf dry mass (DM) and P _N. The thickness of palisade parenchyma contributed to the total leaf thickness (263.1±1.5 μm) by 47 %, spongy layer thickness 38 %, adaxial epidermis and cuticle thickness 9 %, and abaxial epidermis and cuticle thickness 6 %. Variation in leaf size during leaf expansion might be attributed to a combination of cells density and length, and it is confirmed by the significant (p<0.001) correlations among these traits. Q. ilex leaves reached 90 % of their definitive structure before the most severe drought period (beginning of June — end of August). The high leaf mass area (LMA, 15.1±0.6 mg cm⁻²) at full leaf expansion was indicative of compact leaves (2028±100 cells mm⁻²). Air temperature increasing might shorten the favourable period for leaf expansion, thus changing the final amount of biomass per unit leaf area of Q. ilex.     

Nitrogen fertilization effects on leaf morphology and evaluation of leaf area and leaf area index prediction models in sugar beet

In a two-year experiment (2002–2003), five N application rates [0, 60, 120, 180, and 240 kg(N) ha⁻¹, marked N₀, N₆₀, N₁₂₀, N₁₈₀, and N₂₄₀, respectively] were applied to sugar beet cv. Rizor arranged in a Randomized Complete Block design with six replications. Leaf shape parameters [leaf area (LA), maximum length (L), maximum width (W), average radial (AR), elongation (EL), and shape factor (SF)] were determined using an image analysis system, and leaf area index (LAI) was non-destructively measured every two weeks, from early August till mid-September (four times). Years, samplings, and their interaction had significant effects on the determined parameters. Fertilization at the highest dose (N₂₄₀) increased L and sampling×fertilization interaction had significant effects on LA, L, W, and SF. For this interaction, W was the best-correlated parameter with LA and LAI meaning that W is a good predictor of these parameters. Two proposed models for LA estimation were tested. The model based on both leaf dimensions [LA = 0.5083 (L×W) + 31.928] predicted LA better than that using only W (LA = 21.686 W − 112.88). Instrumentally measured LAI was highly correlated with predicted LAI values derived from a quadratic function [LAI = −0.00001 (LA)² + 0.0327 LA − 2.0413]. Thus, both LA and LAI can be reliably predicted non-destructively by using easily applied functions based on leaf dimensions (L, W) and LA estimations, respectively.     

Leaf area prediction for corn (<Emphasis Type="Italic">Zea mays</Emphasis> L.) cultivars with multiregression analysis

Leaf area is one of the most important parameter for plant growth. Reliable equations were offered to predict leaf area for Zea mays L. cultivars. All equations produced for leaf area were derived as affected by leaf length and leaf width. As a result of ANOVA and multiregression analysis, it was found that there was a close relationship between actual and predicted growth parameters. The produced leaf-area prediction model in the present study is LA = a + b L + c W + d LZ where LA is leaf area, L is leaf length, W is maximum leaf width, LZ is leaf zone and a, b, c, d are coefficients. R ² values were between 0.88–0.97 and standard errors were found to be significant at the p<0.001 significance level.     

Growth pattern of <Emphasis Type="Italic">Bidens cernua</Emphasis> L.: relationships between relative growth rate and its physiological and morphological components

Seedlings of Bidens cernua L. emerged when mean air temperature was 17.0±1.3 °C. The highest net photosynthetic rate (P _N), 13.8±0.8 μmol(CO₂) m⁻² s⁻¹, was monitored during the vegetative period (May–August), decreasing on an average by 50 % during flowering (August–September) and during fruiting (September–November) phases. The senescence phase (October–November) was characterised by 79, 58, and 18 % decrease of P _N, chlorophyll content, and leaf area (LA), respectively, from the maximum values. The time span from seedling emergence to the end of fruiting phase was 202 d. The total plant biomass was 1.58±0.05 g of which 81 % was aboveground plant portion. The total dry mass relative growth rate averaged over the assimilation period was 0.0804±0.0002 kg kg⁻¹ d⁻¹, and it was correlated to both the net assimilation rate (NAR) and the leaf area ratio (LAR).     

Evaluation of a leaf area prediction model proposed for sunflower

Six leaf samplings were conducted in two sunflower (Helianthus annuus L.) hybrids during the 2006 growing season in order to evaluate a simple model proposed for leaf area (LA) estimation. A total of 144 leaves were processed using an image analysis system and LA, maximum leaf width (W) [cm], and midvein length (L) [cm] were measured. Also, LA was estimated using the model proposed by Rouphael et al. (2007). Measured LA was exponentially related with L and W, and the W-LA relationships showed higher r ². Estimated LA was strongly and exponentially related with L. Strong, linear relationships with high r ² between estimated and measured LA confirmed the high predictability of the proposed model.     

Environmental induced variations in leaf dark respiration and net photosynthesis of <Emphasis Type="Italic">Quercus ilex</Emphasis> L.

The relationships between dark respiration rate (R _D) and net photosynthetic rate (P _N) in Quercus ilex L. shrubs growing at the Botanical Garden in Rome were analysed. Correlation analysis of the data sets collected in the year 2006 confirmed the dependence among the considered leaf traits, in particular, R _D was significantly (p<0.05) correlated with P _N (r = 0.40). R _D and P _N increased from March to May [1.40±0.10 and 10.1±1.8 μmol(CO₂) m⁻² s⁻¹ mean values of the period, respectively], when air temperature was in the range 14.8–25.2 °C, underlining the highest metabolic activity in the period of the maximum vegetative activity that favoured biomass accumulation. On the contrary, the highest R _D [1.60±0.02 μmol(CO₂) m⁻² s⁻¹], associated to the lowest P _N rates (44 % of the maximum) and carbon use efficiency (CUE) in July underlined the mobilization of stored material during drought stress by a higher air temperature (32.7 °C).     

Leaf anatomy during leaf development of photoautotrophically <Emphasis Type="Italic">in vitro</Emphasis>-grown tobacco plants as affected by growth irradiance

Tobacco (Nicotiana tabacum L.) plants were cultured in vitro photoautotrophically at three levels of irradiance (PAR 400–700 nm): low (LI, 60 μmol m⁻² s⁻¹), middle (MI, 180 μmol m⁻² s⁻¹) and high (HI, 270 μmol m⁻² s⁻¹). Anatomy of the fourth leaf from bottom was followed during leaf development. In HI and MI plants, leaf area expansion started earlier as compared to LI plants, and both HI and MI plants developed some adaptations of sun species: leaves were thicker with higher proportion of palisade parenchyma to spongy parenchyma tissue. Furthermore, in HI and MI plants palisade and spongy parenchyma cells were larger and relative abundance of chloroplasts in parenchyma cells measured as chloroplasts cross-sectional area in the cell was lower than in LI plants. During leaf growth, chloroplasts crosssectional area in both palisade and spongy parenchyma cells in all treatments considerably decreased and finally it occupied only about 5 to 8 % of the cell cross-sectional area. Thus, leaf anatomy of photoautotrophically in vitro cultured plants showed a similar response to growth irradiance as in vivo grown plants, however, the formation of chloroplasts and therefore of photosynthetic apparatus was strongly impaired.     

Leaf area estimation of sunflower leaves from simple linear measurements

Simple, accurate, and non-destructive methods for determining leaf area (LA) of plants are important for many experimental comparisons. Determining the individual LA of sunflower (Helianthus annuus L.) involves measurements of leaf parameters such as length (L) and width (W), or some combinations of these parameters. Two field experiments were carried out during 2003 and 2004 to compare predictive equations of sunflower LAs using simple linear measurements. Regression analyses of LA vs. L and W revealed several equations that could be used for estimating the area of individual sunflower leaves. A linear equation having W² as the independent variable provided the most accurate estimate (r ² = 0.98, MSE = 985) of sunflower LA. Validation of the equation having W² of leaves measured in the 2004 experiment showed that the correlation between calculated and measured areas was very high.     

Application of linear models for estimation of leaf area in soybean [<Emphasis Type="Italic">Glycine max</Emphasis> (L.) Merr]

Leaf area estimation is an important measurement for comparing plant growth in field and pot experiments. In this study, determination of the leaf area (LA, cm²) in soybean [Glycine max (L.) Merr] involves measurements of leaf parameters such as maximum terminal leaflet length (L, cm), width (W, cm), product of length and width (LW), green leaf dry matter (GLDM) and the total number of green leaflets per plant (TNLP) as independent variables. A two-year study was carried out during 2009 (three cultivars) and 2010 (four cultivars) under field conditions to build a model for estimation of LA across soybean cultivars. Regression analysis of LA vs. L and W revealed several functions that could be used to estimate the area of individual leaflet (LE), trifoliate (T) and total leaf area (TLA). Results showed that the LW-based models were better (highest R ² and smallest RMSE) than models based on L or W and models that used GLDM and TNLP as independent variables. The proposed linear models are: LE = 0.754 + 0.655 LW, (R ² = 0.98), T = −4.869 + 1.923 LW, (R ² = 0.97), and TLA = 6.876 + 1.813 ΣLW (summed product of L and W terminal leaflets per plant), (R ² = 0.99). The validation of the models based on LW and developed on cv. DPX showed that the correlation between calculated and measured LA was strong. Therefore, the proposed models can estimate accurately and massively the LA in soybeans without the use of expensive instrumentation.