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Research Article
 

Evaluation of Three Wild Species of Almond on the Basis of Their Morphological Characters



B. Baninasab and M. Rahemi
 
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ABSTRACT

The present study aims to evaluate the seedling behaviour of Amygdalous scoparia, A. webbii and A. orientalis at the inter-specific level. The analysis of variance showed a significant difference between species. However, A. scoparia had highest stem height and leaf length. At the end of the experiment, the thickest stems were developed by A. scoparia, whereas the thinnest stems by A. orientalis. A. webbii produced more number and longer roots per seedling than the other two species. The correlation between various morphological traits showed that a few shoot characters were significantly correlated with root traits. However, leaf length, leaf width, leaf area, root number and root diameter for P. webbii and leaf number, leaf length, leaf width, petiole length and root number characters for P. scoparia and stem height, leaf number, leaf length, petiole length, internode length and root number for P. orientalis were found to be important morphological traits to evaluate seedling charactristics of wild almond genotypes before their nursery test.

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  How to cite this article:

B. Baninasab and M. Rahemi, 2007. Evaluation of Three Wild Species of Almond on the Basis of Their Morphological Characters. Journal of Plant Sciences, 2: 61-67.

DOI: 10.3923/jps.2007.61.67

URL: https://scialert.net/abstract/?doi=jps.2007.61.67

Introduction

The cultivated almond (Prunus amygdalus Batsch) belongs to Rosaceae family, subfamily Prunoideae and typified by a drupe fruit structure (Kester and Gradiziel, 1996). Wild populations of almond species representing a wide range of morphological and geographical forms have evolved throughout southwest and central Asia from Turkey and Syria into the Caucasus Mountains, through Iran and into the deserts of Tian-Shan and Hindu Kush Mountains of Tadjikystan, Uzbckistan and Afghanistan (Browicz, 1969; Browicz and Zohary, 1996; Denisov, 1998; Kester et al., 1990). Over 30 species have been described by botanists may represent subspecies or ecotypes within a broad collection of genotypes which are adapted to a range of ecological niches in the deserts, steppes and mountains of central Asia (Kester and Gradiziel, 1996).

P. orienatlis, P. webbii and P. scoparia are the three wild species of almond naturally distributed in many parts of Iran (Sabeti, 1994). Because of their adaptability to severe environmental conditions, they can be used in semi-desert areas to control soil erosion.

Kester and Gradziel (1996) reported that immense possibilities exist for rootstock improvement through the use of other almond species either by direct selection within the species or by their hybridization with cultivars almond. The wide genetic diversity present among related almond species provides an enlarged pool of available germplasm that has not been sufficiently exploited (Grasselly, 1977). These group of related species provide a potential source of variability including hardiness and late bloom (e.g., P. webbii, P. bucharica), self-fertility (P. webbii and P. mira), modified growth habit and tree size (P. webbii and P. argentea) but they might be expected to result in combinations of genes with unexpected phenotypic expressions (Kester et al., 1990). Vlasic (1977) concluded that the sources of drought tolerance may come from other almond species which are highly xerophytic including P. webbii. P. webbii can be used as a rootstock for almond, nectarine and peach (Alberghina, 1978; Dimitrovski and Ristevski, 1973). According to Dimitrovski and Ristevski (1973) P. webbii is dwarf rootstock for cultivated almond. They reported that, seedlings of P. webbii made 30-50% less growth than those of P. amygdalus and almond cvs grafted on P. webbii showed a similar reduction in vigor. Chilling as expressed by vegetative bud break in relation to flowering may also be a useful indicator of rest requirement (Kester and Gradiziel, 1996). P. orientalis plants leaf out later than the opening of flowers and this trait may be associated with increased tolerance to blossom freezing (Buyukilmaz and Kester, 1976).

For rootstock production, reliable seed materials with fast seedling growth are required in the nursery. Since Iran is extremely rich in wild almond tress, finding such seed materials should not be difficult. These species can be used as a rootstock for almond after testing their effects on the scion productivity, nut quality and their tolerance to soil-borne diseases.

There is no study in the literature demonstrating variation of seedling characteristics of wild almond species. Therefore, this study aims to evaluate seedling behavior of P. orientalis, P. webbii and P. scoparia at the inter-specific level.

Materials and Methods

Seeds of P. orientalis, P. webbii and P. scoparia were obtained from the Research Centre of Natural Resources and Animal Science at Shiraz. Table 1 enlist the seed traits of wild almonds tested. Sound seeds of all species were mechanical scarified and then soaked in water for 48 h. The nuts were mixed with peat-moss (3:1, peat-mass:seed (V/V)) and stratified at 4±1°C for 30 days.

After stratification, nuts were sown directly in 5 kg black plastic bags filled with a 1:1:1 (V/V) mixture of fine sand, leaf mould and soil. The bags were then transferred to the glasshouse, with an average temperature of 29.8±5°C under natural photoperiod for the whole period of the experiment. The experiment was arranged in a completely randomized design with ten replications and five plants per replication. Four months after sowing, seedlings were removed from the containers and the root system was carefully washed for the removal of media and following observations were recorded. Table 2 enlist the traits surveyed in this study.


Table 1: Quantitative nut traits of wild almonds tested
Image for - Evaluation of Three Wild Species of Almond on the Basis of Their Morphological Characters

Table 2: The list of traits and their measures
Image for - Evaluation of Three Wild Species of Almond on the Basis of Their Morphological Characters

Correlations were performed between morphological traits of the seedling characteristics of each species.

The data was statically analyzed and the mean were compared using Duncan’s Multiple Range Test (DMRT). Data recorded as percentage were analyzed after appropriate statistical transformation. Correlation coefficients among morphological traits were calculated using the SAS package program.

Results and Discussion

The analysis of variance showed a significant difference among species for most of the traits measured. Differences for most traits showed high genetic variability among these species. Therefore, this genetic variability can be used either in rootstock selection or rootstock breeding programs. Table 3 and 4 shown comparison of means of shoot and root traits measured of all species, respectively.

The stem height was not significantly different between P. scoparia and P. orienatlis, whereas the differences were significant between these two species and P. webbii (Table 3). However, at the end of the study, P. scoparia had the tallest (20.58 cm) and P. webbii the shortest stem (14.88 cm) (Table 3). These results are in agreement with Dimitrovski and Ristevski (1973) who found that P. webbii was dwarfing rootstock for cultivated almond.

Another character to be taken into consideration was the tree growth capacity, as determined by stem diameter. Stem diameter, which is essential to allow early budding and transplanting in to orchard. Differences in stem diameter were observed among the species (Table 3). The thickest stems were developed by P. scoparia (1.83 mm), whereas the thinnest stems were measured in P. webbii and P. orieantalis (1.40 and 1.30 mm, respectively) (Table 3). Emergence time of the species grown in the greenhouse may affect seedling growth. In this experiment, we observed emergence in P. scoparia was earliest than the other species. Such a difference might explain the season for better stem height and diameter of P. scoparia than the other species. The reasons for the differences in stem diameter might be controlling other genetic factors responsible for seedling growth.


Table 3: Comparison of means of shoot traits measured in wild almonds species
Image for - Evaluation of Three Wild Species of Almond on the Basis of Their Morphological Characters
* In each row or column, means with the similar letter(s) are not significantly different at 1% level of probability using DMRT

Table 4: Comparison of means of root traits measured of wild almonds
Image for - Evaluation of Three Wild Species of Almond on the Basis of Their Morphological Characters
* In each row or column, means with the similar letter(s) are not significantly different at 1% level of probability using DMRT

There is no report in the literature on stem diameter of these species. The leaf number and petiole length of P. orientalis were more and large (33.88 and 2.75mm, respectively) followed by P. scoparia and P. webbii (Table 3). Although, P. webbii produced seedlings with less leaves, but the leaf length, width and area (34.10, 14.25 mm and 309.80 mm2, respectively) were larger than the other species (Table 3). Leaf characters of P. scoparia and P. oreintalis were similar to there reported by Sabeti (1994) and Zeinalabedini et al. (2002).

In this study differences among fresh and dry weight of shoot of the species were not significant (Table 3). However, shoot fresh weight and dry weight were greatest in P. scoparia (Table 3).

The characters of root system have also been determined. The results showed that P. webbii seedlings had more, larger and greater fresh and dry weights of root system (37.42, 407.20 mm, 0.28 and 0.04 g, respectively) than the other two species (Table 4). There is no report in the literature on root system of species and our study shows that there is a variation between the three species with regard to these important traits.

The correlations between pair of traits are shown separately for each species (Table 5-7). Several shoot characters were significantly correlated with root characters. In P. webbii, stem diameter was significantly correlated with leaf number, leaf length and root number. This might be due to the role of the leaf in carbohydrate synthesis and root in the absorption of water and mineral salts. Root diameter was significantly correlated with leaf length, leaf width and leaf area and negatively with shoot fresh and dry weights (Table 5).

In P. scoparia, root length was significantly correlated with leaf width and internode length. Root number was significantly correlated with leaf length, petiole length, internode length and root length (Table 6).

In P. orientalis, stem diameter was significantly correlated with leaf number and negatively with leaf area, internode length, shoot fresh weight, shoot dry weight, root number and root dry weight (Table 7).

These correlations suggest that many of the associations between morphological traits of shoot and root vary between these three species. However, leaf length, leaf width, leaf area, root number and root diameter for P. webbii and leaf length and width, petiole length and root number characters for P. scoparia and stem diameter, leaf number, leaf length, petiole length, internode length and root number for P. orientalis were found to be important morphological traits to evaluate seedling characteristics of almond genotype before nursery test.


Table 5: Correlation between measured traits of P.webbii
Image for - Evaluation of Three Wild Species of Almond on the Basis of Their Morphological Characters
* Significant at the 5% probability level, ** Significant at the 1% probability level

Table 6: Correlation between measured traits of P. scoparia
Image for - Evaluation of Three Wild Species of Almond on the Basis of Their Morphological Characters
Image for - Evaluation of Three Wild Species of Almond on the Basis of Their Morphological Characters
* Significant at the 5% probability level, ** Significant at the 1% probability level

Table 7: Correlation between measured traits of P. orientalis
Image for - Evaluation of Three Wild Species of Almond on the Basis of Their Morphological Characters
* Significant at the 5% probability level, ** Significant at the 1% probability level

Acknowledgments

We thank Dr. M. Mobli, Mr. G. Oji and B. Modarres for their valuable help with this study.

REFERENCES

1:  Alberghina, O., 1978. The wild almond, Amygdalus webbii, of southwest Sicily. Tecnica-Agricoia, 30: 385-393.

2:  Browicz, K., 1969. Amygdalus L. In: Flora Iiranica, Rechinger, K.H. (Ed.), Akademische Druck-U. Verlagsanstalt, Graz, pp: 166-168

3:  Browicz, K. and D. Zohary, 1996. The genus Amygdalus L. (Rosaceae): Species relationships, distribution and evolution under domestication. Genet. Resour. Crop Evol., 43: 229-247.
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4:  Buyukilmaz, M. and D.E. Kester, 1976. Comparative hardiness of flower buds and blossoms of some almond genotypes in relation to time of bloom and leafing. J. Am. Soc. Hortic. Sci., 101: 344-347.

5:  Denisov, V.P., 1998. Almond genetic resources in the USSR and their use in production and breeding. Acta Hortic., 224: 299-306.

6:  Dimitrovski, T. and B. Ristevski, 1973. Investigation on the suitability of the wild almond, Amygdalus webbii, as a rootstock. Jugoslovensko-Vocarstvo, 6: 15-21.

7:  Grasselly, C., 1977. Reflexions sur les caracteristique des especes sauvages d'amygdalus et sur leur utilization eventual dans des programmes d'amelioration genetic. Proceedings of 3rd Colloque GREMPA, October 3-7, 1977, CIHEAM, Bari, Italy, pp: 70-77

8:  Kester, D.E., T.M. Gradziel and C. Grasselly, 1990. Almond (Prunus). In: Genetic Resources of Temperate Fruits and Nut Crops, Morre, J.N. and I.R. Ballington (Eds.), Int. Soci. Hortic. Sci. Wageningen, Wageningen, pp: 701-758

9:  Kester, D.E. and T.M. Gradiziel, 1996. Almonds. In: Fruit Breeding, Janick, J. and J.N. Moore (Eds.). Vol. III. Nuts. John Wiley and Sons, New York, pp: 1-97

10:  Sabeti, H., 1994. Forests, Trees and Shrubs of Iran. Iran University of Science and Technology Press, Tehran, pp: 810

11:  Vlasic, A., 1977. L'amygdalus webbii spach edi soulsi ibridi co1 pesco come portaninnestro del mandorlo. Proceedings of 3rd Colloque GREMPA, October 3-7, 1977, Bari, Italy, pp: 80-81

12:  Zeinalabedini, M., V. Grigorian, M. Valizadeh, M. Moghaddam and S.M. Modares Hashemi, 2002. Genetic diversity among wild populations of almond (Amygdalous sp.) in Isfahan Province as determined by some morphological and seed storage proteins. Iranian Hortic. Sci. Technol., 3: 15-28.

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