Impaginato 27 Adv. Hort. Sci., 2018 32(1): 27-32 DOI: 10.13128/ahs-21157 Phenology and pomology of almond’s cultivars and genotypes using multivariate analysis A. Imani 1, M. Shamili 2 (*) 1 Temperate Fruit Research Center, Horticultural Research Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaji, Iran. 2 Horticulture Department Agriculture Faculty, University of Hormozgan, Bandar Abbas, Iran. Key words: flower, kernel, multiple regression, nut, path analysis, yield. Abstract: The present research aimed to study the flower and fruit properties of 60 almond’s cultivars and genotypes. All fruit and kernel traits had high heri- tability (ranged from 20.73 to 92.13%). Double kernel and pistil length showed the most and few genotypic variation, respectively. The most yield belonged to Filippo Ceo, K8-24, Fragiulo and K9-24 (6.9, 6.84, 6.78 and 7.6 kg/tree respec- tively). Multivariate analysis was the applied technique to determine the rela- tionship among important traits. Kernel weigh caused yield directly and kernel width indirectly. To estimate kernel weight, kernel variables had less R square (0.61) than nut variables (0.94). 1. Introduction The efficiency of plants breeding program depends on selection of desirable parents and progenies. Almond cultivars differ in the growth and branching pattern, as well as bearing habit (Duval and Grasselly, 1994). Self-compatibility (Socias i Company and Felipe, 1988; Ortega and Dicenta, 2003), late blooming (Vargas and Romero, 2001), flower density, production rate (Dicenta et al., 1993 a; Gradziel and Kester, 1998), fruit maturity period (Kester and Asay, 1975; Dicenta et al., 1993 b) and kernel properties (Spiegel-Roy and Kochba, 1974, 1981; Kester et al., 1991) are the main almond breeding objectives, to be informed by the relationship among these traits, facilitates the breeding process, and selection of the desirable almond genotypes (Dicenta et al., 1993 a). Multivariate analysis is the common technique to evaluate almond genotypes according to quantitative and qualitative characteristics (De Giorgio and Polignano, 2001; De Giorgio et al., 2007). Lansari et al. (1994) used this method in order to evaluate morphological variation of almonds varieties. Their results indicated that nut and kernel traits, compare to (*) Corresponding author: shamili@ut.ac.ir Citation: IMANI A., SHAMILI M., 2018 - Phenology and pomology of almond’s cultivars and genotypes using multivariate analysis. - Adv. Hort. Sci., 32(1): 27-32 Copyright: © 2018 Imani A., Shamili M. This is an open access, peer reviewed article published by Firenze University Press (http://www.fupress.net/index.php/ahs/) and distribuited under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Data Availability Statement: All relevant data are within the paper and its Supporting Information files. Competing Interests: The authors declare no competing interests. Received for publication 14 August 2017 Accepted for publication 16 November 2017 AHS Advances in Horticultural Science Adv. Hort. Sci., 2018 32(1): 27-32 28 vegetative characteristics, has important role in genotype distinction. De Giorgio and Polignano (2001) mentioned fruit characteristics are the most effective variables to differentiate almond geno- types. De Giorgio et al. (2007) divided 88 almond varieties, into seven separate groups based on mor- phological traits. Besides, it has been reported that almond nut length and thickness, and kernel length have significant correlations with kernel length, moreover kernel width have most positive effect on kernel weight (Spiegel-Roy and Kochba, 1981; Kester et al., 1977). The direct and indirect interaction of the traits which affect the yield can be used as a breeding tool, in this work we analyzed 60 local and foreign almond genotypes and cultivars to understand the casual relation among some important traits. 2. Materials and Methods Plant materials This research carried out as randomized complete blocks design, during the years 2013 -2014, in Horticultural sciences research institute, Karaj, Iran (51°35’E, 48°N, 1297 m above sea level, average annual max/min air temperature of 31.3/22.5°C, mean RH of 60%, the average annual precipitation of 148 mm, shallow soil pH=7.5). The average of mini- mum daily temperature (°C) of January to April (years 2013-2014) is given at figure 1 (Based on Iranian meteorological organization data). We evaluated 60 almond genotypes (Table 1) using almond descriptors (Gülcan, 1985) (Table 2). All genotypes were 7-year-old and except Tuono, Supernova, Filippo Ceo and Fragiulo, the others were self-incompatible. Data analysis Descriptive statistics (minimum, maximum and mean) was used to describe and summarize the data by SPSS 22 and SAS9. Variance components, variance coefficients and Heritability were calculated by Excel 2013. Multivariate regression analysis was performed to assess the relationship among variables by adjusted R square (ADJRSQ) procedure. Briefly, the subsets of Fig. 1 - Average of minimum daily temperature (°C) from January to April (years 2013-2014). Cultivar and genotypes origin Foreign Local Nonpareil Boty k1-25 K14-24 K9-2 A-200 Mission Roby D124 K13-40 K9-32 K9-20 Perlice Karmel K8-24 K9-24 K6-5 K1-16 Padre Sh-21 Shekofeh K8-B K16-23 12-3 Tuono Sh-6 Mamaie K11-9 Sahand 8-3 Filippo Ceo Ne Plus Ultra Sefid K4-13 K9-7 D101 Marcona Sh-17 K8-32 K3-8 K5-6 Supernova K1-5 K6-4 K5-17 Rabie Fragiulo Sh-13 K2-22 K5-27 D-99 Sh-12 Sh-15 K3-12 K3-19 D-8 A-230 Saba Talkh asli Z-3 Table 1 - Almond cultivars and genotypes evaluated in the pro- ject Table 2 - Quantitative traits using in 60 almond cultivars and genotypes Trait Measuring unit Measuring method Flower characteristics Flower size cm Caliper Petal length cm Caliper Petal width cm Caliper Stamen number number Counting Pistil length cm Caliper Pistil Diameter cm Caliper Nut characteristics Nut Length mm Caliper Nut Width mm Caliper Nut Thickness mm Caliper Nut Weight g Digital balance Kernel characteristics Kernel Length mm Caliper Kernel Thickness mm Caliper Kernel Width mm Caliper Kernel Weight g Digital balance Kernel Percentage % Calculating Double kernels % Counting Yield Kg/tree Digital balance Imani and Shamili - Phenology and pomology of almond’s cultivars 29 the independent variables, which have the best esti- mation of some important dependent variables (like flower size, double kernel percentage) were select- ed. Then Path analysis was used to describe the direct relation among variables focusing on causality. 3. Results Table 3 represents the statistical descriptive and variance component. Based on the results, the most genotypic variance (126.37 and 99.08 respectively) belonged to the double kernel and the kernel per- centage, while pistil length and thickness had the least (0.01). The most heritability belonged to kernel percent- age and double kernel (92.13% and 89.74% respec- tively). The rest of the variables had heritability over 20.73%. Various researches reported different almond kernel weigh heritability such as 64% (Kester et al., 1977), 45% (Spiegel-Roy and Kochba, 1981) and 78% (Dicenta et al., 1993 b); so to have high kernel weight (5.1 grams) progenies, the parents with high kernel weight should be chosen. In the present study kernel weigh heritability was 70.15%. Filippo Ceo (9.6 kg/tree), k8-24 (6.84 kg/tree), Fragiulo (6.78 kg/tree) and k9-24 (6.7 kg/tree) had the most yield and Talkh asli (2.33 kg/tree), D101 (2. 44 kg/tree), 12-3 (2.45 kg/tree), 8-3 (2.8 kg kg/tree) and Sefid (2.82 kg/tree) had the lowest. In some environmental conditions (e.g. low tem- perature before flowering) almond progenies have been produced double kernel nuts even if the par- ents did not appearance the trait (Egea and Burgos, 1995; Sánchez-Pérez et al., 2007). It has been found that complexity and dominant inheritance of the mentioned trait is affected by genotype and pheno- type, which have been reported by several researchers (Dicenta et al., 1993 a, b; Arteaga and Socias i Company, 2001; Sánchez-Pérez et al., 2007). In our study, the double kernel varied from 0 to 57%, suggests it have been influenced by the genotypes differences. Food industries seeks for almond progenies with the medium thickness and smooth surface nuts (Sánchez-Pérez et al., 2007). We found nut thickness between 9.08-20 mm. Kester et al. (1977) reported nut thickness heritability about 0.71, whereas we estimated it about 0.41. In the present investigation, stepwise regression was used to identify the yield causal system which separates independent variables into direct and indi- rect ones (Table 4 and Fig. 2). According the data, nut weight had the most standardized beta (0. 944). As well as the nut related traits (length, width, thickness Table 3 - Descriptive statistic, heritability, phenotypic and genotypic coefficients of almond traits Traits Max Mean Min Variance components Heritability Coefficient of variance Phenotypic Environmental Genotypic Genotypic Phenotypic Flower size 5 3.88 2.9 0.39 0.11 0.28 71.04 13.57 16.10 Petal length 2.5 1.65 1 0.13 0.05 0.08 59.08 16.81 21.87 Petal width 1.8 1.35 0.98 0.08 0.04 0.04 52.38 15.54 21.47 Stamen number 37 26.83 15 25.57 4.00 21.57 84.35 17.31 18.84 Pistil length 1.72 1.46 1.1 0.03 0.02 0.01 45.65 8.10 11.98 Pistil thickness 0.52 0.26 0.1 0.04 0.03 0.01 23.08 38.21 79.54 Nut length 47.17 33.35 26.59 24.05 4.67 19.38 80.60 13.20 14.70 Nut width 28.82 20.08 13.28 15.66 4.00 11.66 74.45 17.00 19.70 Nut thickness 20 14.07 9.08 9.64 5.67 3.98 41.23 14.17 22.06 Nut weight 4.76 2.72 0.97 5.47 4.33 1.13 20.73 38.99 85.65 Kernel length 30.89 24.29 18 8.50 1.00 7.50 88.23 11.27 12.00 Kernel width 16.78 12.10 9.19 4.94 1.63 3.31 66.97 15.03 18.37 Kernel thickness 9.12 6.98 4.61 1.38 0.63 0.74 54.02 12.35 16.81 Kernel weight 1.67 1.06 0.56 0.13 0.04 0.09 70.15 28.82 34.41 Kernel percentage 68.88 42.02 23.52 137.17 10.80 126.37 92.13 26.75 27.87 Double Kernel 57 9.95 1 110.41 11.33 99.08 89.74 100.00 105.56 Yield 7.4 5.21 2.62 2.69 0.95 1.74 64.72 25.31 31.46 Adv. Hort. Sci., 2018 32(1): 27-32 30 and weight); the kernel variables (length, width and percentage) significantly influenced the yield (Table 4). The most direct effect related to kernel weight, nut weight, nut thickness, nut width and nut length, respectively (Fig. 2). It is recommended that these traits can be assumed as the selection criteria to improve almond commercial yield. Also, direct and indirect variables which effect kernel weight (Table 5), double kernel and flower size have been evaluated via multivariate linear regres- sion. Nut characteristics (nut weight and width) had more regression coefficients. Kernel weight estima- tion entering three independent variables (for exam- ple, kernel length, width and thickness) had more R2 than two variables (like kernel length and width). Double kernel estimation using nut traits did not have acceptable R2, neither kernel traits. Although the flower size was influenced by the number of sta- mens, petal length, and width significantly, but the R2 was very low (0.353). 4. Discussion and Conclusions Yield improvement is the most important objec- tive of the almond breeding programs. The commer- cial yield of almond fruit trees (kg kernel per tree) results the interaction of self (in)compatibility, flower Table 4 - Yield causality analysis and stepwise correlation coefficients Yield Nut weight Kernel weight Kernel thickness Kernel width Nut width Nut weight 0.488** 1 Kernel weight 0.655** 0.780* 1 Kernel thickness 0.565** 0.630** 0.697** 1 Kernel width 0.612** 0.625** 0.752** 0.778** 1 Nut width 0.466** 0.568** 0.587** 0.594** 0.832** 1 Kernel length 0.266* 0.608** 0.524** 0.281* 0.516** 0.381** Nut length 0.266* 0.580** 0.489** 0.203 Kernel percentage -0.570** -0.176 Flower size 0 Pistil length -0.088 Petal width -0.053 Stamen number -0.153 Pistil length -0.110 Nut thickness -0.022 Double Kernel 0.140 Fig. 2 - Path analysis for traits that affect almonds yield (beta coefficients have given at parenthesis). Table 5 - Kernel weight estimation based on different independent variables Dependent variable Independent variables entering to equation R2 Kernel weight Nut weight Nut width Kernel thickness Kernel percentage 0.9461 Kernel weight Nut length Nut weight Nut width Double Kernel 0.9455 Kernel weight Nut weight Nut width Kernel percentage 0.9454 Kernel weight Kernel length Kernel width Kernel thickness 0.6193 Kernel weight Kernel length Kernel thickness 0.5888 Kernel weight Kernel width Kernel thickness 0.5827 Kernel weight Kernel length Kernel width 0.5759 *, **, denote statistical significance at 5 and 1% levels, respectively. Imani and Shamili - Phenology and pomology of almond’s cultivars 31 buds density, fruit abscission, kernel dry weight and Kernel size (Garcia et al., 1996). Although some small kernel cultivar (such as ‘Felisia’) are ideal for chocolate bars and almond drops (Socias i Company and Felipe, 1999), large ker- nel almond are valued almost. The trait, as well as its correlated trait, varies each year. High correlation between almond in shell weight and kernel weight (-0.82) (Sánchez-Pérez et al., 2007), in shell kernel ratio and in shell weight (-0.72) and in shell kernel ratio and kernel weight (0.7) (Dicenta and García, 1993) have been reported previ- ously. Based on our result nut length significantly corre- lated with nut width (0.59) and nut weight (0.71). Moreover kernel weight showed high correlation with kernel length (0.64) and nut weight (0.69). the kernel weight influenced the yield directly and nut weight indirectly. While nut width, weight and diam- eter influenced nut length. Based on the results K8-24 had relatively high nut length (33.5 mm), nut width (28.82 mm), kernel length (25.01 mm) and kernel width (7.48 mm). Fragiulo, K8-24 and Filippo Ceo had relatively high kernel weight (1.486, 1.378 and 1.373 gr respective- ly). K8-24 and Fragiulo had relatively high nut and kernel weight. According to our findings, Kernel weight can be used as a selection criterion for almond breeding programs. Regression models for kernel weight esti- mation revealed that nut characteristics like length, width and weight had more R2 (0.94) than the kernel characteristic such as weight, width and percentage (R2= 0.61). Acknowledgements The research was funded by the Iranian Agricultural Research, Education and Extension Organization (AREEO. Project number: 8204-1. 2013/5/2). References ARTEAGA N., SOCIAS I COMPANY R., 2001 - Heritability of fruit and kernel traits in almond. - Acta Horticulturae, 591: 269-274. DE GIORGIO D., LEO L., ZACHEO G., LAMASCESE N., 2007 - Evaluation of 52 almond (Prunus amygdalus Batsch.) cultivars from the Apulia region in Southern Italy. - J. Hort. Sci. Biotech., 82(4): 541-554. DE GIORGIO D., POLIGNANO G.B., 2001 - Evaluating the biodiversity of almond cultivars from a germplasm col- lection field in southern Italy. - Sust. Glob. Farm, 56. DICENTA F., GARCÍA J.E., 1993 - Inheritance of kernel flavour in almond. - Heredity, 70(3): 308-312. DICENTA F., GARCÍA J.E., CARBONELL E., 1993 a - Heritability of flowering, productivity and maturity in almond. - J. Horti. Sci., 68: 113-120. DICENTA F., GARCÍA J.E., CARBONELL E., 1993 b - Heritability of fruit characters in almond. - J. Hort. Sci., 68: 121-126. DUVAL H., GRASSELLY C., 1994 - Behaviour of some self- fertile almond selections in the south-east of France. - Acta Horticulturae, 373: 69-74. EGEA J., BURGOS L., 1995 - Double kernelled fruits in almond (Prunus dulcis Mill.) as related to pre-blossom temperatures. - Ann. Appl. Biol., 126: 163-168 GARCÍA J.E., DICENTA F., BERENGUER T., EGEA J., 1996 - Programa de mejora del almendro del CEBAS-CSIC (Murcia). - Fruticultura Profesional, 81: 64-70. GRADZIEL T.M., KESTER D.E., 1998 - Breeding for self-fertil- ity in California almond cultivars. - Acta Horticulturae, 470: 109-117. GüLCAN R., 1985 - Descriptor list for almond (Prunus amygdalus) (revised). - FAO, IBPGR Secretariat, Rome, Italy. KESTER D.E., ASAY R., 1975 - Almonds, pp. 387-419. - In: JANICK J., and J.N. MOORE (eds.). Advances in fruit breeding. Purdue Univ. Press, West Lafayette, Ind., USA, pp. 623. KESTER D.E., GRADZIEL T.M., GRASSELLY C., 1991 - Almonds (Prunus). - Acta Horticulturae, 209: 701-758. KESTER D.E., HANSCHE P.E., BERES W., ASAY R.N., 1977 - Variance components and heritability of nut and kernel traits in almond. - J. Amer. Soc. Hort. Sci., 102: 264- 266. LANSARI A., IEZZONI A.F., KESTER D.E., 1994 - Morphological variation within collections of Moroccan almond clones and Mediterranean and North American cultivars. - Euphytica, 78: 27-41. ORTEGA E., DICENTA F., 2003 - Inheritance of self-compati- bility in almond: breeding strategies to assure self- compatibility in the progeny. - Theor. Appl. Genet., 106: 904-911. SÁNCHEZ-PÉREZ R., ORTEGA E., DUVAL H., MARTÍNEZ- GÓMEZ P., DICENTA F., 2007 - Inheritance and relation- ships of important agronomic traits in almond. - Euphytica, 155: 381-391. SOCIAS I COMPANY R., FELIPE A.J., 1988 - Self-compatibili- ty in almond: transmission and recent advances in breeding. - Acta Horticulturae, 224: 307-317. SOCIAS I COMPANY R., FELIPE A.J., 1999 - ‘Blanquerna’, ‘Cambra’ y ‘Felisia’. Tres nuevos cultivares autóga- mos de almendro. - Inf. Técn. Econ. Agrar., 95(2): 111-117. Adv. Hort. Sci., 2018 32(1): 27-32 32 SPIEGEL-ROY P., KOCHBA J., 1974 - The inheritance of bit- ter and double kernel characters in the almond. - Z. Pflanzenzücht., 71: 319-329. SPIEGEL-ROY P., KOCHBA J., 1981 - Inheritance of nut and kernel traits in almond. - Euphytica, 30: 161-174 VARGAS F.J., ROMERO M.A., 2001 - Blooming time in almond progenies. - CIHEAM, Options Méditerra- néennes, 56: 29-34.