Mass modeling of pomegranate (Punica granatum L.) fruit with some physical characteristics

Among physical characteristics, dimensions, mass, volume and projected areas are important parameters in sizing and grading systems. Fruits with the similar weight and uniform shape are desirable in terms of marketing value. Therefore, grading fruit based on weight reduces packing and handling costs and also provides suitable packing patterns. The different grading systems require different fruit sizing based on particular parameters. In this study pomegranate mass was predicted by applying different physical characteristics with linear and nonlinear models as three different classifications: (1) single or multiple variable regressions of pomegranate dimensional characteristics, (2) single or multiple variable regression of pomegranate projected areas and (3) estimating pomegranate mass based on its volume. The results showed that mass modeling of pomegranate based on minor diameter and three projected areas are the most appropriate models in the first and second classifications, respectively. In third classification, the highest determination coefficient was obtained for mass modeling based on the actual volume as R² = 0.99 whereas corresponding values were 0.93 and 0.79 for assumed pomegranate shapes (oblate spheroid and ellipsoid), respectively. In economical and agronomical point of view, suitable grading system of pomegranate mass was ascertained based on minor diameter as nonlinear relation M = 0.06c² − 4.11c + 143.56, R² = 0.91.     

Estimation of individual leaf area,fresh weight,and dry weight of hydroponically grown cucumbers (Cucumis sativus L.) using leaf length,width, and SPAD value

Non-destructive and mathematical approaches of modeling can be very convenient and useful for plant growth estimation. To predict individual leaf area, fresh weight, and dry weight of a cucumber (Cucumis sativus L.), models were developed using leaf length, leaf width, SPAD value, and different combinations of these variables. Eight regression equations, commonly used for developing growth models, were compared for accuracy and adaptability. The three nonlinear models developed were as follows: individual leaf area (LA) = −210.61 + 13.358W + 0.5356LW (R² = 0.980^***), fresh weight (FW) = −2.72 + 0.0135LW + 0.00022LWS (R² = 0.956^***), and dry weight (DW) = 0.25 − 0.00102LS + 0.000077LWS (R² = 0.956^***), where L is the leaf length, W the leaf width, S the SPAD value, and LWS = L × W × S. For validation of the model, estimated values for individual leaf area, fresh weight, and dry weight showed strong agreement with the measured values, respectively. Leaf dry weight, especially, was estimated with a higher degree of accuracy through the use of a SPAD value, as well as leaf length and width. Therefore, it is concluded that models presented herein may be useful for the estimation of the individual leaf area, fresh weight, and dry weight of a cucumber with a high degree of accuracy.     

Pollination with laser-irradiated pollens breaks cross-incompatibility between zicaitai (Brassica campestris var. purpurea) and ornamental kale (Brassica oleracea var. acephala) to produce hybrids with the aid of ovule culture

The objective of this study was to produce interspecific hybrids between an Ogura-cytoplasmic male sterile (CMS) line of zicaitai (Brassica campestris var. purupurea, 2n = 20) and cultivars of ornamental kale (Brassica oleracea var. acephala, 2n = 18) to develop a CMS system for hybrid seed production. Pollination with pollen grains of ornamental kales irradiated at a power output of 9.0 mW with a He–Ne laser for 3 min could overcome the cross-incompatibility between the species concerned. Intact hybrids could be efficiently produced from ovules cultured on Murashige and Skoog media supplemented by 0.2 mg l⁻¹ 6-benzyladenine. Chromosome number of hybrids was confirmed to be 2n = 19. Hybrids resembled ornamental kales in leaf morphology and in vernalization response. Pollens of hybrids had a sterile appearance. Moreover the hybridity of the putative hybrids was confirmed by RAPD data on a DNA fragment of 820 bp.     

Non-destructive leaf area estimation in chestnut

In this research, an equation for estimating the leaf area was derived for the chestnut tree by using 18 chestnut genotypes and by measuring the lamina width, length and leaf area without damage being caused in 2004–2005. Multiple regression analysis for the genotypes was separately performed. The proposed leaf area (LA) estimation model is: LA = 3.36 + 0.11L² − 0.26L²/W² + 1.1W², R² = 0.988, where LA is the leaf area, W is the leaf width and L is the leaf length. The model was validated by measuring leaf samples of the SE-21-2 genotype in different climate conditions in 2004–2005.     

The influence of flesh colour and growing locality on polyphenolic content and antioxidant activity in potatoes

Compounds contained in potato tubers that may act as antioxidants have been attracting increased attention. The main antioxidants in potatoes are polyphenolic compounds. The total polyphenolic (TP) content and antioxidant activity (AA) in potato tubers of four yellow-fleshed cultivars and two purple-fleshed cultivars from the 2004 harvest were tested. The total polyphenolic content was determined using the Folin-Ciocalteau reagent (FC) and the antioxidant activity, with the DPPH method using stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH·). Significant differences were found in total polyphenolic content between the yellow-fleshed cultivars Karin, Impala, Ditta, and Saturna. Significant differences between yellow and purple-fleshed potatoes were found: the yellow-fleshed cultivars had an average of 2.96 g gallic acid equivalents (GAE) per kg DM, the purple-fleshed cultivars 4.68 g GAE per kg DM. Significant differences in AA between the yellow and purple-fleshed cultivars were determined (yellow-fleshed in an average of 139.3 mg equivalents of ascorbic acid [EAA] per kg DM, purple-fleshed 332.3 mg EAA per kg DM) as well as between the purple-fleshed cultivars Valfi (298 mg EAA per kg DM) and Violette (366 mg EAA per kg DM). The major antioxidants in purple-fleshed cultivars were anthocyanidins petunidin (Valfi 92%_rel) and malvidin (Violette 85%_rel). Cv. Violette contained three times higher content of anthocyanidins than cv. Valfi. Among four experimental localities, the higher situated potato-growing region of Stachy (locality with the lowest average annual and daily minimum temperatures and the highest sum of precipitation in the vegetative period) differed significantly from other localities by a higher TP content, AA and yield in the analyzed cultivars. A high positive correlation between antioxidant activity and total polyphenolic content with R = 0.8648, R² = 0.7478 (P = 0.0001) was found.     

Prediction of saffron crocus corm mass by geometrical attributes

Saffron (Crocus sativus L.) is the most precious spice plant in the world. The only method for the reproduction of saffron is cultivation of corm. It is necessary to know relationships between mass and size of saffron corms in order to design and develop of planting, harvesting, grading and handling equipments. The objective of this research was to determine the most accurate models to predict saffron corm mass based on geometrical attributes. Models for predicting the mass of corms were classified as follows: (1) single or multiple variable regressions of saffron corm mass and dimensional characteristics, (2) single or multiple variable regressions of saffron corm mass and projected areas and (3) single regression of saffron corm mass based on its actual volume and calculated volume assuming the saffron corm shapes of sphere, oblate spheroid and ellipsoid. Three sets of corms were considered from Torbat-e-Heydareyeh, Kashmar, and Gonabad fields in Khorasan province of Iran. Some physical characteristics that were needed for the saffron corm mass modelling were determined for the three regions corms. The results showed that there were not significant differences between mean values of mass, height, major diameter, geometric mean diameter and projected areas of saffron corms for the three regions. However, there were significant differences between saffron corm minor diameter, volumes, corm density, bulk density and porosity for the three regions. Therefore, the mass of the corms was modelled based on the height, major diameter and projected areas irrespective to the regions, whereas in the third classification models, the mass of the corms was modelled for each region. The statistically significant fitted models were selected based on the higher coefficient of determination (r²) and lower regression standard error (RSE). The results of mass modelling showed that the prediction of saffron corm mass based on the major diameter (M = 0.0017a^2.5168, r² = 0.94, p < 0.05) and the first projected area (M = 0.0019 (PA₁)^1.2916, r² = 0.96, p < 0.05) were the most appropriate models. The model that predicted the mass of saffron corm based on the estimated volume of an ellipsoid shape was found to be the most appropriate. The developed models and data of physical characteristics of saffron corms could be used for designing and developing the saffron corm grader and other cultivation equipments.     

Stoloniferous shoot protoplast,an efficient cell system in potato for somatic cell genetic manipulations

The present study reports that protoplasts isolated from stoloniferous shoots (SS) of potato represent an efficient system for somatic cell genetic manipulations. SS were established from single-node cuttings on MS medium supplemented with either 0.1 or 0.2 M sucrose (Suc), and protoplasts were isolated and cultured within the alginate strip, following an improved method. SS induced by 0.1 M Suc yielded 8–22 × 10⁵ protoplasts g⁻¹ fresh mass, with a high morphogenic competence. However, 0.2 M Suc-induced SS yielded protoplasts that contained large amounts of starch grains, resulting in their high degree of fragility, delayed cell division and poor morphogenic competence. For symmetric somatic hybridization (electrofusion) between Solanum tuberosum Gp. Tuberosum androgenic (di)haploid (2n = 2x = 24) ‘C-13’ and diploid (2n = 2x = 24) wild species S. pinnatisectum, protoplasts isolated from 0.1 M Suc-induced SS were also found to be most responsive. Out of several putative somatic hybrids, there were two tetraploids and five diploids, with 48 and 24 chromosomes, respectively at all the three shoot layers (L₁–L₃). This precluded the occurrence of mixoploidy vis-à-vis chimaerism in regenerants, as common in somatic fusion involving mesophyll protoplasts of S. pinnatisectum. Nuclear microsatellite analyses based on the two single-locus nSSR loci (STM0037 and STM2030) confirmed that one of the tetraploids was a true nuclear hybrid (heterokaryon), while the other a homokaryon of the Tuberosum parent ‘C-13’. The use of 0.2 M Suc-induced SS protoplasts for fundamental studies on tissue- and/or cell type-specific transient gene expression underlying tuberization has been discussed.     

Water status,leaf area and fruit load influence on berry weight and sugar accumulation of cv. ‘Tempranillo’ under semiarid conditions

Berry weight (BW) and sugar concentration (SC) are relevant indices in viticulture since they can be easily measured and, when considered together, give a relatively fair estimation of grape quality. This work aims to evaluate the influence of water availability, leaf area and fruit load on BW and SC, estimating the relative importance of these factors. Leaf area (LA), berry number (BN), yield (YLD), water potential in summer (ψ_pd-s), BW and SC were measured in 16 and 17 ‘Tempranillo’ vineyards in 1999 and 2000, respectively. In all the vineyards, according to local practices, the irrigation amount decreased as summer progressed. The study vineyards comprised a broad range of situations concerning leaf area, fruit load and water status in summer. Average leaf water potential in summer and LA/BN ratio, when considered together, estimated properly BW (R² = 0.91; P < 0.001) and, in a similar way, ψ_pd-s and LA/YLD ratio estimated SC (R² = 0.74; P < 0.001). The relative weight of ψ_pd-s in both relationships was much higher than that of any of the LA:fruit ratios, showing that, under semiarid conditions, water availability plays the main role in regulation of berry growth and sugar accumulation and, therefore, the highest attention should be paid in these areas to irrigation management, seeking the degree of stress that allows optimizing the combination of yield and berry quality in each situation.     

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.     

Cultivar and anatomical analysis of corolla enlargement of petunia (Petunia hybrida Vilm.) by cytokinin application

We found that the corolla of petunia (Petunia hybrida Vilm.) could be conspicuously enlarged by the separate application of three cytokinins: forchlorfenuron (CPPU), N⁶-benzylaminopurine (BA), and zeatin. To obtain the same enlargement as that achieved by CPPU, approximately 30 and 900 times the concentration of BA and zeatin, respectively, were required. CPPU at 3.2 μmol/L increased the limb area of the corollas of 15 cultivars to between 1.3 and 2.4 times (1.8 times on average) the size of the control area. The increase was negatively correlated (R = 0.58) with the “genetic” limb area (i.e., that of the untreated plant). The enlargement of the corolla caused by cytokinin application was mainly attributed to an increase in cell number in most cultivars. This increase resulted from a high rate of cell proliferation and from prolongation of the cell proliferation phase during corolla development. This anatomical change caused by cytokinin application was similar to the anatomical difference among cultivars because genetic differences in limb area resulted mainly from differences in cell number.     

Evaluating variability of root size system and its constitutive traits in hot pepper (Capsicum annum L.) under water stress

The importance of root size system has long been recognized as crucial to cope with drought conditions. This investigation was conducted to: (i) evaluate the variability in root size system of hot pepper at maturity; (ii) estimate the effect of root size system on yield under drought conditions; and (iii) effect of water stress on xylem vessel development and total xylem cross-sectional area in roots of hot pepper cultivars. Twelve diverse hot pepper cultivars were grown in wooden boxes with two different water treatments, normal and in 50% water application as water deficit condition. Mean primary root length (PRL) showed a significant positive correlation with final fruit yield at normal as well as stressed condition. Total dry mass of fruit was reduced by 34.7% in drought treatments (DI) compared to full watered treatment (FI). At harvest, water-stressed plants had 21% lower root dry weight mass but higher root:shoot ratio other than FI. PRL, lateral root density, total xylem area per root cross-section showed a significant positive relationship with fruit yield. Also, lateral root density was higher in cultivars with higher xylem density, particularly in tolerant cultivars. Lateral root density (r = 0.847, P < 0.001) and total xylem cross-sectional area in root (r = 0.926, P < 0.001) were tightly related with total biomass production. The importance of root traits contributing to withstand drought in hot pepper is discussed.     

Aneuploid strawberry (2n = 8x + 2 = 58) was developed from homozygous unreduced gamete (8x) produced by second division restitution in pollen

Unreduced gamete formation is significant in the evolutionary development of complex polyploidy series found in wild strawberry, genus Fragaria (Rosaceae). Also, it is important for genetics and breeding in strawberry plants to elucidate the mechanism of unreduced gamete formation. The objective of this study was to search for ploidy anomalies resulting from artificial diploid × octoploid crosses, and examine the mechanism through which these unreduced gametes were produced. Five everbearing cultivars of Fragaria vesca L. diploid (2n = 2x = 14) were crossed with pollen from six June-bearing cultivars of Fragaria × ananassa Duch., octoploid (2n = 8x = 56). A total of 3000 mature seeds, 100 from each of the 30 parental combinations were sown at 23 °C/20 °C (day/night) under artificial lighting with a 16 h day. The seedlings were transplanted to pots and grown in a greenhouse. Reproductive and morphological observations, flow cytometry analyses, chromosome counts and DNA analyses using CAPS markers were performed to identify the genetic background of the offspring. Most of the seed (79%) did not germinate or died soon after germination. Of the seedlings produced, 7% seemed to be pure F. vesca based on morphological characteristics, flow cytometry analyses and chromosome counts; 14% were pentaploids (2n = 5x = 35), 0.1% were hexaploids (2n = 6x = 42), and 0.03% (one individual) was aneuploid (2n = 8x + 2 = 58). Electrophoresis banding patterns obtained by CAPS marker analysis were heterozygotic in the 8x pollen parent but homozygotic in the aneuploid progeny. Judging from the chromosome counts and the CAPS marker analysis, the aneuploid was the result of a homozygous unreduced pollen grain (8x) crossed with an incomplete chromosome compliment from the egg. Because of the homozygosity, the unreduced male gamete must have been derived from second division restitution (SDR) in the octoploid pollen parent.     

Production of inter-section hybrids between Primula filchnerae and P. sinensis through ovule culture

Inter-section hybrids were obtained in the reciprocal crosses between Primula filchnerae (2n = 2x = 24) of Sect. Pinnatae and P. sinensis ‘Fanfare’ (2n = 2x = 24) of Sect. Auganthus by rescuing ovules on half-strength (1/2) Murashige and Skoog's (MS) medium supplemented with 50 g l⁻¹ sucrose, 2.5 g l⁻¹ gellan gum, 0.1 mg l⁻¹ α-naphthaleneacetic acid (NAA), 0.1 mg l⁻¹ 6-benzyladenine (BA) and 50 mg l⁻¹ gibberellic acid (GA₃). In ovule culture, germination occurred with radicle elongation but no plumule was observed. The radicle kept on the initial medium showed root proliferation with callus formation. When the calluses were transferred to (1/2)MS media containing 30 g l⁻¹ sucrose and 3 g l⁻¹ gellan gum, without plant growth regulators (PGRs) or with 1 mg l⁻¹ zeatin and 0.1 mg l⁻¹ NAA, plantlets were regenerated. The plants thus obtained were confirmed to be hybrids through flow cytometry (FCM) and random amplified polymorphic DNA (RAPD) analyses. The hybrid obtained when P. filchnerae was used as the maternal parent was diploid, whereas hexaploid hybrid was obtained when using P. sinensis as the maternal parent. The hexaploid hybrid might be produced through chromosome doubling of a triploid originated from the fertilization of P. sinensis with unreduced pollen of P. filchnerae.     

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.     

Anthocyanins from flowers of Hippeastrum cultivars

The anthocyanins, cyanidin 3-O-(6″-O-α-rhamnopyranosyl-β-glucopyranoside) (1) and pelargonidin 3-O-(6″-O-α-rhamnopyranosyl-β-glucopyranoside) (2), were isolated from the ornamental flowers of a Ugandan Hippeastrum cultivar by a combination of chromatographic techniques, and their structures were elucidated mainly by the use of homo- and heteronuclear nuclear magnetic resonance spectroscopy and electrospray mass spectrometry. The same anthocyanins were found in six different Hippeastrum cultivars purchased in Norway. However, the absolute amount of the anthocyanins (0.08–1.79 mg/g, fresh weight) and the relative proportions of the individual anthocyanins varied from cultivar to cultivar (13.2–96.5% of 1). The colours of the fresh petals of the three cultivars ‘Red Lion’, ‘Royal Velvet’ and ‘Liberty’ were described by the CIELab coordinates L^* (lightness), C^* (chroma) and h_ab (hue angles). All the cultivars showed hue angles corresponding to scarlet nuances (h_ab = 22–35°), with the highest value in ‘Red Lion’. The most reddish petals (in ‘Royal Velvet’) contained the highest relative proportion of 1. Thus, the in vivo colours of these cultivars seem to be correlated with the relative proportions of individual anthocyanin in the petals.     

Phenolic compounds and antioxidant activity of the apple flesh and peel of eleven cultivars grown in Brazil

The total phenolic, flavanol, monomeric anthocyanin contents and the antioxidant activity of flesh and peel of 11 apple cultivars from Brazil were investigated. Concentrations of the parameters measured differed significantly among the apple cultivars and were highest in the peel compared to the flesh. Total phenolic content (mg GAE/100 g fresh matter) ranged from 128.3 (Golden Delicious) to 212.0 (Epagri-F₅P₂₈₃) in the flesh and 304.6 (Golden Delicious) to 712.6 (Catarina) in the peel. Total flavanol content (mg CAE/100 g fm) varied from 11.7 (Epagri-SJ11) to 28.2 (Epagri-F₄₃P₂₃) and from 32.4 (Epagri-SJ11) to 147.7 (Catarina) in the flesh and peel, respectively. COOP-24 peel had the highest total anthocyanin content. The Epagri-F5P283 and Epagri-F43P23 flesh and Catarina peel had the highest antioxidant activity while Golden Delicious flesh and peel had the lowest. The total phenolic content and antioxidant activity were significantly correlated in both flesh (R² = 0.717) and peel (R² = 0.716). The contribution of phenolics to the antioxidant activity in peel suggests that their removal may induce a significant loss of antioxidants.     

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.     

Night interruption promotes vegetative growth and flowering of Cymbidium

The effects of night interruption (NI) were examined on the vegetative growth and flowering of Cymbidium ‘Red Fire’ and ‘Yokihi’. Plants were grown under 9/15 h ambient light/dark (control), 9 h ambient light plus night interruption (22:00–02:00 h) with low light intensity at 3–7 μmol m⁻² s⁻¹ (LNI) and 9 h ambient light plus NI with high light intensity at 120 μmol m⁻² s⁻¹ (HNI) conditions. The number of leaves, leaf length, number of pseudobulbs and pseudobulb diameter increased in both LNI and HNI compared to controls for both cultivars. While none of the control plants flowered within 2 years, 100% of the ‘Yokihi’ and 80% of the ‘Red Fire’ plants grown under HNI condition flowered. In the LNI group, 60% of the plants flowered in both cultivars. Plants in the HNI group showed a decreased time to visible inflorescence and flowering than those in the LNI group. The number of inflorescences and florets were greater in the plants grown under HNI than those in the LNI group. The tallest plants at flowering were in the HNI group in both cultivars. NI with low light intensity can be used effectively to promote flower induction with increased growth rate during the juvenile stage in Cymbidium. To obtain high quality plants, however, NI with high light intensity strategies should be considered.     

Fruit calcium content and lipoxygenase activity in relation to albinism disorder in strawberry

Nutrient elements and lipoxygenase (LOX) activity were determined in strawberry fruit to establish a relationship, if it exists, between nutrient ratios (N/Ca and K/Ca), and lipoxygenase activity with albinism disorder. About 33% strawberry fruit were affected by albinism. Etna had highest incidence of albinism (48.6%) and Sweet Charlie the lowest (16.2%). Dry matter content (%) was lower in albino fruit (5.23%) than normal fruit (7.36%). The concentration of N, P, and Mg did not differ significantly, but that of K (1.87 mg g⁻¹ fresh weight) was notably higher and of Ca (0.105 mg g⁻¹ fresh weight) was lower in albino fruit than normal fruit. Consequently, the nutrient ratios, N/Ca (9.78) and K/Ca (16.96) were higher in albino fruit than normal fruit. Cultivars differed widely in respect to dry matter (%), mineral content and nutrient ratios. LOX activity determined on dry weight or fresh weight basis was significantly higher in albino fruit than normal fruit, with significant differences among cultivars. Positive correlations existed between nutrient ratios and albinism incidence (r = +0.338), LOX activity and albinism incidence (r = +0.412), and LOX and nutrient ratios (r = +0.448). Thus, it appears from the study that calcium and LOX activity may not the basic cause of albinism in strawberry, but these may be involved in senescence or fruit ripening process, as LOX activity was lower in albino than in normal fruit.     

Relationship between inbreeding coefficients and plant height of 1-year-old seedlings in crosses among Japanese pear (Pyrus pyrifolia Nakai) cultivars/selections

Plant height, a vigor trait, in 1-year-old seedlings made from Japanese pear (Pyrus pyrifolia) cultivars/selections was measured using 994 individuals from 29 families. The family mean of plant height was negatively correlated (r = −0.72**) to the inbreeding coefficients (F). The regression of the family mean (Fm) on the F value (Fm = 130 − 104F) showed that inbreeding depressions were 8%, 20%, and 40% for F = 0.1, 0.25, and 0.5, respectively. According to the regression, the family mean at F = 0 was estimated at 130 cm. These results showed that the vigor was greatly influenced by inbreeding in Japanese pear. Within-family variances, the genetic segregation of offspring in a family, differed according to family. The proportions of offspring with plant height above 130 cm (estimated Fm for F = 0) were extremely low, i.e., 0–17% for 0.5 ≤ F < 0.60 and 0–8% for F = 0.75.