Non-destructive leaf area estimation model for faba bean (Vicia faba L.)

In this study, a leaf area estimation model was developed for faba bean (Vicia faba L.) using the linear measurements such as lamina length (L) and width (W) by stepwise regression analysis. Leaflets from fourteen faba bean genotypes, including three cultivars (Eresen-87, Filiz-99 and Lara), two lines (FLIP85-172FB and FLIP86-116FB) and nine local genotypes, were used to develop the model in 2003-2004. The proposed leaf area (LA) estimation model is LA = 0.919 + 0.682LW, R² = 0.977. In 2004–2005 growing season, this model was validated by measuring new leaf samples from the different level of the plant canopy (lower, middle and upper) of faba bean cvs. Eresen-87 and Filiz-99 sown in both autumn and late winter. Produced model in this study can be reliably used for estimating area of leaf samples from the different level of the plant canopy of faba bean cvs. Eresen-87 and Filiz-99 sown in both autumn and late winter.     

Chemical composition of chestnut cultivars from Spain

Chestnut cultivation and production in Spain has employed grafted seedlings from selected local cultivars. Previously, we have characterised the Spanish cultivars by morphological and molecular markers. We are presenting in this paper the proximate analysis and mineral content for the main Spanish cultivars. A total of 131 samples were collected from 47 cultivars in six important Spanish chestnut production regions; located in the North such as Asturias, Castilla-León (El Bierzo) and Galicia; in the Central such as Extremadura and in the South such as Andalucía; as well as the Canary Islands, the southermost part of Spain near to North Africa. High variability in chemical composition between cultivars and regions corresponded to the high genetic variability between cultivars. Correlations with environmental parameters were low, indicating that differences found between regions were probably reflecting the differences between cultivars. In Central and Southern Spain, some cultivars presented lowest moisture content due to the low summer rainfall in these regions. Differences in starch and total sugar contents were high and were negatively correlated with each other. There was no negative correlation between nut size and total sugar content. Lowest values of fibre content and ease of digestibility were found in cultivars from Galicia and Extremadura. No significant differences in Fe, Zn and Cu were found although Zn content is twice the value reported for European chestnuts. This work would be a valuable reference to chestnut quality for the food processing industry, nutritionists, breeders and growers alike.     

A simple model for estimating leaf area of hazelnut from linear measurements

Simple, accurate and non-destructive models determining leaf area of plants are important for many experimental comparisons. Determining the individual leaf area (LA) of hazelnut (Corylus avellana L.) involves measurements of leaf parameters, such as length (L) and width (W), or some combinations of these parameters. Two-year investigation was carried out during 2005 (on 20 genotypes) and 2006 (on one cultivar) under open field conditions, respectively, to test whether a model could be developed to estimate leaf area across genotypes and environments. Regression analyses of LA versus L and W revealed several models that could be used for estimating the area of individual hazelnut leaves. A linear model having LW as the independent variable (LA = 2.59 + 0.74LW) provided the most accurate estimate (R² = 0.982, MSE = 29) of hazelnut LA. Validation of the model having LW of leaves measured in the 2006 experiment coming from other genotype grown under different environmental conditions showed that the correlation between calculated and measured areas was very high.     

Modeling individual leaf area of ginger (Zingiber officinale Roscoe) using leaf length and width

Leaf area estimation is an important biometrical observation one has to do for comparing plant growth in field and pot experiments. In this study, a leaf area estimation model was developed for ginger (Zingiber officinale Roscoe), using linear measurements of leaf length (L) and maximum width (W). Leaves from five ginger varieties (Varada, Rejatha, Mahima, Maran and Himachal) were used to develop the model in 2006–2007. The actual leaf area (LA) was measured with a leaf area meter (LI-3100, LI-COR, Lincoln, NE, USA) and taken as reference LA. The linear measurements were used to build linear (LA = a + b × L × W) and power models (LA = α × (L × W)^β) for each variety, as the modeling among variety were not different from each other, data for all five varieties have been pooled and compared with earlier models by graphical procedures and statistical criteria such as Mean Square Error (MSE), Root Mean Square Error (RMSE) and Chi-square (χ²). The selected model was validated during 2007–2008. The validation data set was used to produce a validation model for each variety by re-estimating the model parameters to develop the estimation model and the models were compared for consistency. The predicted LA (PLA) was compared with observed LA (OLA) by graphical procedures and lack of agreement was evaluated by calculating the relative bias, estimated by the mean of differences (d) and the standard deviation (SD) of the differences. Normality test was carried out by Spearman's rank correlation coefficient (r_s) and residuals were normally distributed. Finally, the proposed model for leaf area estimation of ginger is LA = −0.0146 + 0.6621 × L × W, R² = 0.997. This model can be reliably used for estimating leaf area of ginger non-destructively. The same equation can be extrapolated to all varieties and land races of ginger as it is vegetatively propagated crop with narrow genetic variability.     

Canopy profiles of starch and leaf mass per area in greenhouse tomato and the relationship with leaf area and fruit growth

Better knowledge of patterns of carbon allocation in plants growing in CO₂-supplemented atmospheres may help to guide more efficient management of CO₂ applications in tomato greenhouses. Leaf starch and LMA (leaf mass per unit area) were investigated in commercially grown greenhouse tomato plants to determine the distribution and influence of leaf area and fruit load on these measures.     

Small-scale effects of historical land use and topography on post-cultural tree species composition in an Alpine valley in southern Switzerland

Investigations of spatial patterns in forest tree species composition are essential in the understanding of landscape dynamics, especially in areas of land-use change. The specific environmental factors controlling the present patterns, however, vary with the scale of observation. In this study we estimated abundance of adult trees and tree regeneration in a Southern Alpine valley in Ticino, Switzerland. We hypothesized that, at the present scale, spatial pattern of post-cultural tree species does not primarily depend on topographic features but responds instead to small-scale variation in historical land use. We used multivariate regression trees to relate species abundances to environmental variables. Species matrices were comprised of single tree species abundance as well as species groups. Groups were formed according to common ecological species requirements with respect to shade tolerance, soil moisture and soil nutrients. Though species variance could only be partially explained, a clear ranking in the relative importance of environmental variables emerged. Tree basal area of formerly cultivated Castanea sativa (Mill.) was the most important factor accounting for up to 50% of species’ variation. Influence of topographic attributes was minor, restricted to profile curvature, and partly contradictory in response. Our results suggest the importance of biotic factors and soil properties for small-scale variation in tree species composition and need for further investigations in the study area on the ecological requirements of tree species in the early growing stage.     

Calibration and validation of regression model for non-destructive leaf area estimation of saffron (Crocus sativus L.)

Leaf area measurements are required in several agronomical and physiological studies. Usually, there is an interest for measurement methods that are simple, quick and that will not destroy the leaf. The objectives of this study were to establish equations to estimate leaf area (LA) by using length (L), width (W) and dry weight (DW) of saffron leaves. Leaves of different sizes were collected from the experimental area at different time intervals. Leaf area was measured with an automatic measuring device and leaf dimensions were determined with a ruler. An equation for estimating the leaf area from L and W was developed and validated with the area of leaves collected during different periods. Regression analyses of LA versus L, W, LW and DW led several models that could be used for estimating the area of individual saffron leaves. A exponential model having L as the independent variables [LA = 191.33e^(L)0.0037] provided the most accurate estimate (R² = 0.9373, RMSE = 27.68) of saffron leaf area. Validation of the regression model showed that the correlation between measured and simulated values by the use of this equation was very high.     

Pome fruit viruses at the Canadian Clonal Genebank and molecular characterization of Apple chlorotic leaf spot virus isolates

A survey for apple and pear viruses was carried out at the Canadian Clonal Genebank (CCG), Harrow, Ontario, Canada, during the fall/winter of 2007 and spring of 2008. Leaves and/or dormant cuttings were randomly collected from 438 to 122 accessions of apple and pear, respectively. Samples were tested by Double Antibody Sandwich-Enzyme Linked Immunosorbent Assay (DAS-ELISA) for the presence of Apple chlorotic leaf spot virus (ACLSV), Apple stem pitting virus (ASPV), Apple stem grooving virus (ASGV) and Apple mosaic virus (ApMV). Infection rates for apples were ACLSV (48.1%), ASGV (10%), ASPV (6.6%) and ApMV (7.1%), and for pears ACLSV (42.6%). ACLSV was detected and characterization by multiplex RT-PCR with primers targeting a fragment of 677 bp corresponding to the partial coat protein (CP), movement protein (MP) and untranslated (3′UTR) region in 22 accessions of apple and pear. Multiplex RT-PCR showed a higher sensitivity over the ELISA test. The nucleotide and amino acid deduced partial CP identities ranged from 82.6–100% to 91–100%, respectively, while partial MP identities was 62.5–100% at aa level based on the amplified fragment appropriate for partial MP using a frame shift, among 22 ACLSV isolates. Phylogenetic analyses based on the partial CP region clustered CCG ACLSV isolates in two different groups, while those based on the partial MP region embraced CCG ACLSV isolates in two sub-clusters within the same group. This is the first report on the detection of ACLSV, ASPV, ASGV and ApMV at CCG, and the molecular characterization of ACLSV isolates in apple and pear plants from worldwide countries to deduce possible heterogeneity and evolution.     

Seed inoculation with Azospirillum mitigates NaCl effects on lettuce

Data on the growth-promoting effects of Azospirillum on lettuce exposed to either normal or saline conditions, is scarce. Lactuca sativa L., cv Mantecosa seeds were colonized with A. brasilense Sp245 cells during imbibition. Germination percentages were determined after 7 d treatments with 0, 30, 50 or 80 mol m⁻³ NaCl. In another experiment, seeds germinated in Hoagland were irrigated for 30 d with 0, 30, 50 or 80 mol m⁻³ NaCl supplemented media. Vegetative growth proceeded in a growth chamber with a 13–11 h day–night cycle. Buffer-imbibed seeds were considered non-inoculated controls. Plant samples were taken at 0, 14, 20, and 30 d after the onset of NaCl treatments and dissected in aerial and root portions. The weights of both tissues were measured. Azospirillum-inoculated seeds had significantly higher germination percentages than controls in all treatments. Inoculated dried seeds stored up to 30 d maintained such characteristic in most of the treatments, particularly at 80 mol m⁻³ NaCl. Plants grown from inoculated seeds and irrigated with saline media displayed higher total fresh and dry weights and biomass partition to the aerial portion, than non-inoculated controls. Azospirillum-inoculated lettuce seeds had better germination and vegetative growth than non-inoculated controls after being exposed to NaCl.     

Novel genomic and EST-derived SSR markers in Japanese chestnuts

A total of 366 novel simple sequence repeat (SSR) markers were developed in Japanese chestnut (Castanea crenata), comprising 220 genomic SSRs derived from enriched genomic libraries and 146 expressed sequence tag (EST)–SSRs obtained from large-scale EST sequencing analysis. Thirty accessions, comprising Japanese, Chinese (C. mollissima), European (Castanea sativa), and American chestnuts (Castanea dentata), were used for evaluation of SSR polymorphism and transferability across species. The EST–SSRs showed less polymorphism than the genomic SSRs and were more transferable. The mean observed heterozygosity (H_O) and the mean expected heterozygosity (H_E) of genomic SSRs in the Japanese chestnuts were 0.63 and 0.68, respectively; those of EST-SSRs were each 0.47. Although about 80% of the genomic SSRs were amplified in all 4 species, more than 95% of the EST–SSRs were transferable across all 4 species. The many novel SSRs developed in this study will be applicable for the construction of genetic linkage maps, QTL analysis of phenotypic traits, high-throughput genotyping of marker-assisted selection, and association genetics.     

Re-constructing data of leaf area increment in the greenhouse pot chrysanthemum cultivar ‘Lompoc’

A dynamic model was developed for re-constructing data of shoot leaf area increment in pot chrysanthemum. From specified final areas of individual leaves and time of anthesis of the terminal flower, the model can re-construct dynamic growth of each leaf on side shoots using a modified Richards function. In the model, leaf growth is related to a relative time index ranging from zero to unity, where zero is the start of short day treatment and unity corresponds to anthesis of the terminal flower. Experiments were conducted under greenhouse conditions to collect data for parameter estimation, model verification and model validation. An allometric relationship between leaf length and leaf area was used to estimate leaf area non-destructively from leaf length recordings. When compared with the data used for parameter estimation, the model simulations fitted the data with R² values ranging from 0.979 to 0.998. In the validation trial the model showed a tendency of over estimation early leaf growth but could explain variations in the data with R² values ranging from 0.899 to 0.993.     

Artificial decrease of leaf area affects inflorescence quality but not floral size in Antirrhinum majus

We have studied the effect of artificial modification of leaf area on inflorescence and floral quality in Antirrhinum majus. We used two treatments where we clipped all the leaves except the first three pairs of true leaves, or we cut every leaf visible by the time the plant had six leaf pairs. Decreased leaf area caused a decrease in stem elongation that could be traced back to a decrease in internode elongation. Leaves left on the plant increased their size beyond control. Inflorescence quality was strongly affected since total floral number showed a strong decrease with reduced leaf area. In contrast, floral size hardly changed. Breeding programs in Antirrhinum should take into account growth conditions affecting leaf area when searching for changes in inflorescence quality while floral size can be screened independently of this factor.     

Effects of leaf aging and light duration on photosynthetic characteristics in a cucumber canopy

Photosynthetic characteristics, chlorophyll index and leaf area were examined in selected leaves of cucumber (Cucumis sativus L. cv. Euphorbia). In the first experiment, plants of cucumber were grown horizontally at a lighting period of 20 h day⁻¹. Photosynthetic measurements in horizontally growing cucumbers showed that there was no decline in photosynthetic capacity when cucumber leaves are developing under good light conditions. In a second experiment, plants were grown in a traditional high-wire cultivation system under 20 h day⁻¹ lighting period until they reached final height and then exposed to different lighting periods (20 and 24 h day⁻¹) for 3 weeks. In stands of cucumber plants photosynthetic measurements showed that the lower leaves have a significant reduction in photosynthetic capacity due to reduced light conditions. Three weeks exposure to 24 h day⁻¹ lighting period reduced leaf area by 20%. Plant grown under continuous light had also lower chlorophyll index compared to plants grown under 20 h day⁻¹ lighting period.     

The use of green waste compost in peat-based potting mixtures: Fertilization and suppressiveness against soilborne diseases

Twelve commercially produced Dutch green waste composts were evaluated for their suitability to replace 20% (v/v) peat substrate in the cultivation of ornamentals. Salt concentrations were determined in water extracts of the composts and disease suppressive effects were assessed against various soilborne diseases. The Cl-concentration of the compost extract appeared to be the limiting factor for use of the composts in potting mixtures. The Cl-concentrations in 7 and 1 composts, respectively, were too high to replace 20% of peat for growing salt sensitive and moderately salt sensitive plants, according to guidelines set for these groups of plants. The suppressive effects of the composts were tested in peat-based potting mixtures using three bioassays: Phytophthora cinnamomi—lupin, Cylindrocladium spathiphylli—Spathiphyllum and Rhizoctonia solani AG2-1—cauliflower. Disease levels in compost-amended mixtures were compared with the non-amended controls. None of the composts induced suppressiveness against P. cinnamomi; 3 and 9 composts significantly induced suppressiveness against C. spathiphylli and R. solani, respectively. No significant disease enhancement was observed in any of the bioassays. The pH of the potting mixture showed a negative correlation with suppression of the Rhizoctonia disease (R² = 0.56). The effect of pH (pH 4–6) on suppression of R. solani and P. cinnamomi was further studied in non-amended peat. Disease suppression of R. solani in cauliflower decreased with increasing pH in two different kinds of peat, while there was no effect on P. cinnamomi. The suppressive effect of 3 composts was assessed in two experiments against Fusarium wilt in Cyclamen persicum (caused by F. oxysporum f. sp. cyclamini) and Begonia eliator (caused by F. foetens) under near-commercial conditions. None of the composts had a significant effect on Fusarium wilt in Cyclamen. Two and 3 composts significantly induced suppressiveness against Fusarium wilt in Begonia in the first and second experiments, respectively. No significant differences were observed in growth characteristics between Begonia plants grown in compost-amended and non-amended potting mixture in both experiments. In the second experiment, Cyclamen plants grown in compost-amended potting mixture had significant lower number of flowers than plants grown in non-amended potting mixture, which may have been due to lower concentrations of N in the compost-amended potting mixtures. In conclusion, most composts of the origin and composition tested can replace 20% peat in potting mixtures for moderately salt sensitive and salt tolerant plants. Amendment of these composts can contribute to control of Fusarium wilt in Begonia plants.     

Indicators of nitrogen status for ornamental woody plants based on optical measurements of leaf epidermal polyphenol and chlorophyll contents

Indicators of plant nitrogen (N) status adapted to woody ornamental plants are essential for the adjustment of fertilization practices in nurseries. The objective of this study was to investigate whether optical measurements of leaf epidermal polyphenol (EPhen) and chlorophyll (Chl) contents could be used as N status indicators for woody deciduous and evergreen ornamental plants. One-year-old plants of Lagerstroemia indica, Callicarpa bodinieri and Viburnum tinus were grown outdoors in containers. They received low (TN₁, 4 mg L⁻¹) or high (TN₂, 105 mg L⁻¹) levels of N during 2 months in spring and summer. TN₁ treatment limited shoot growth from 28 to 37 days after treatment initiation in Lagerstroemia and Callicarpa, respectively. Shoot growth was unaffected until day 176 in Viburnum. The mass-based leaf N content (N_M) of a sample of young expanded leaves exposed to direct sunlight was tightly correlated with shoot N content and differentiated treatments several weeks before shoot growth reduction for the three species. N_M was therefore used as an index of plant N status. EPhen and Chl contents were recorded with Dualex™ and SPAD-502 leaf-clip meters, respectively. Dualex values were strongly and negatively correlated with N_M, and differentiated the treatments early in the experiment, in all three species. SPAD values were positively correlated with N_M for Lagerstroemia and Callicarpa, but not for Viburnum, because large variations in leaf mass per area (LMA) in this species compensated for variations in leaf dry mass invested in Chl. The SPAD/Dualex ratio was used to assess changes in the proportion of leaf dry mass allocated to proteins and polyphenols in response to fertilization. It differentiated between the treatments early in the experiment and was correlated with N_M in all three species.     

Nutritional quality of greenhouse lettuce at harvest and after storage in relation to N application and cultivation season

The effect of five levels of nitrogen fertilization on the growth and nutritional quality of Cos lettuce (Lactuca sativa L. cv. Parris Island) at harvest and after storage was studied during autumn and winter in South-West Greece. Plants were cultivated hydroponically in a greenhouse and the nitrate, chlorophyll and ascorbic acid (vitamin C) concentrations within the plant tissues were measured at harvest and following storage at 5 or 10 °C for 10 days. Nitrate accumulated in the leaves with increasing amounts of N within the nutrient solution and was higher in the winter than in the autumn. At the lowest N level (20 mg L⁻¹), the inner leaves accumulated more nitrate than the outer leaves, whereas at higher N levels (140, 200 or 260 mg L⁻¹) nitrate accumulation was higher in the outer leaves. Overall, the highest nitrate concentrations were detected in the petiole and the proximal end of the leaf, but at the lowest N application rate (20 mg L⁻¹) nitrate accumulated in the distal region of the leaf too. Although the nitrate concentrations within the leaves did not change significantly during 10 days storage at 5 or 10 °C, the chlorophyll and vitamin C concentrations decreased. Chlorophyll loss was higher in lettuce that was grown under low N levels and was higher at 10 °C than at 5 °C, but was reduced by enclosure of the lettuce in polyethylene film. It is concluded that the optimum N application rate for Cos lettuce grown hydroponically under cover during autumn and winter in South-West Greece, and in other areas with a similar climate, is 200 mg N L⁻¹ because at this N rate yield is satisfactory and leaf nitrate concentrations are below the maximum acceptable level for human consumption. Nutritional value (vitamin C concentration) and market quality (chlorophyll content) are highest at harvest and decrease during storage, but quality in terms of nitrate concentration does not change.     

Leaf development,net assimilation and leaf nitrogen concentrations of five Prunus rootstocks in response to root temperature

Rootstocks differentially influence tree physiology and these differences may be due to varying responses to root zone temperature (RZT). To determine if this is the case, the physiology, leaf development and nitrogen relationships of five different Prunus rootstocks with chill requirements between 100 and 1100 h were examined during and after growth at RZTs of 5, 12 and 19 °C for 6 weeks. RZT correlated positively with leaf numbers, expansion rates and final leaf area, and significant differences existed among the rootstocks in the magnitude of these parameters at different RZTs. In particular, leaf expansion and area were less affected at low RZT in the low chill varieties. Net assimilation (A_n), leaf nitrogen (N%) and photosynthetic nitrogen use efficiency (A_n/N) also correlated positively with RZT: again, there were differences in the magnitude of these parameters among the rootstocks. No associations amongst A_n, N% or A_n/N could be found for the rootstocks; hence, they all differed in their physiological responses to RZT. Low RZT alone was sufficient to reduce A_n and decreased both leaf area and photosynthetic activity. Leaf expansion was related to N%, as the varieties with the lowest N% also had the lowest expansion rates. Infrared thermography of the cv. Golden Queen showed a negative correlation between RZT and leaf temperature with leaves of plants at the lowest RZT being 2 °C warmer than ambient whilst those at the highest RZT were 2 °C cooler than ambient. These differences were due to transpiration, as transpiration for the variety used decreased with reducing RZT. Transpiration from the other rootstock varieties was lowest at the 5 °C RZT but, depending on variety, at 12 °C was either higher, lower or the same as that from plants whose roots were at 19 °C. Together, the results of this study explain some of the rootstock-induced changes in tree growth and suggest the need to incorporate seasonal changes in RZT into development models for peaches.     

Cross-transferable polymorphic SSR loci in Prunus species

This work reports the transferability and polymorphism of previously reported SSRs in 10 Prunus species. The availability of a large number of SSRs in the genus Prunus makes marker choice random, while preventing comparison of results in fingerprinting studies. The availability of SSR markers, polymorphic in a wide sample of Prunus species, would facilitate marker choice, while allowing the comparison of results. In this work, microsatellite markers useful for analyzing 10 different Prunus species (P. persica, P. dulcis, P. armeniaca, P. domestica, P. insititia, P. salicina, P. cerasifera, P. avium, P. cersus and P. mahaleb) were searched through screening SSRs previously reported to be conserved and/or polymorphic in more than one Prunus species. A selected group of 13 SSRs, transferable to the 10 species, was analyzed in terms of their usefulness for analyzing these species. The amplification range, polymorphism and variability detected by these loci are reported. The information provided will be useful for Prunus genetic studies as well as conservation and management of Prunus germplasm resources.     

Pecan production increased by larger vegetation-free area surrounding the tree

Vegetation control with herbicides is a common practice in pecan [Carya illinoinensis (Wangenh.) K. Koch] orchards that benefits both non-bearing and bearing trees. However, the appropriate size for the vegetation-free area surrounding bearing trees had not been resolved. Vegetation-free circles centered on the Tree 0, 0.9, 1.8, 3.7, and 7.3 m in diameter were established at planting and tree performance evaluated. This study reports the first six years of production that began in the sixth growing season. Yield was not affected by treatment in the first two years of production while yield was low and some trees had not begun to produce. The next four years were characterized by a strong positive relationship between vegetation-free diameter with annual yield and with cumulative yield. Weight per nut and kernel percentage were rarely affected by treatment. Leaf elemental concentrations of selected essential nutrients were not affected by treatment. Trunk diameter was similar among treatments each year. This indicates that yield was improved by the vegetation-free area impacting pistillate flower induction or flower and fruit retention rather than improved tree growth increasing the bearing surface.     

Establishment of efficient regeneration protocol from leaf explants of Iris pumila shoots cultured in vitro

An efficient plant regeneration protocol via somatic embyogenesis by leaf base culture of in vitro grown Iris pumila shoots was developed. Induction of embryogenic calli was achieved on MS media supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D), kinetin (4.5 μM, each) and some additives (L-proline, casein hydrolysate, adenine sulphate and tyrosine). Further differentiation of embryogenic calli was achieved on MS hormone-free media, and on media supplemented with either BAP (4.5 μM) or BAP + zeatin (4.5 and 0.2 μM, respectively), which allowed somatic embryos, as well as shoot-like structures to form. Fully developed somatic embryos germinated on an MS hormone-free medium. An anatomical study confirmed that shoot-like structures represented early germinating stages of somatic embryos. Acclimatization of plants derived from somatic embryos was 64% after 1 year and no morphological variation was observed.