Heritability and Combining Ability for Cold Hardiness from Partial
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HORTSCIENCE 53(4):427–431. 2018. https://doi.org/10.21273/HORTSCI12763-17 (Jalikop and Kumar, 1990). It is widely distributed and have adapted to different environments. Thus, pomegranates display Heritability and Combining Ability for a wide diversity of pomological and tree characteristics. By using available germ- Cold Hardiness from Partial Dialleles plasm, it is possible to develop cultivars with improved winterhardiness and acceptable in Iranian Pomegranate Cultivars fruit quality. Susceptibility to freezing injury is a major environmental factor limiting Ali Akbar Ghasemi Soloklui geographical distribution and growing season Department of Horticultural Science, School of Agriculture, Shiraz University, of many cultivars and affects crop quality and Shiraz, Iran productivity (Thomashow, 1999). Fruit breed- ing efforts have recently focused on the de- Ali Gharaghani1 velopment of cultivars with broader climatic Department of Horticultural Science, School of Agriculture, Shiraz adaptation (such as increased freezing toler- ance for the northern regions), disease and pest University, Shiraz, Iran; and Drought Research Center, School of resistance, and high fruit quality (Galletta and Agriculture, Shiraz University, Shiraz, Iran Ballington, 1996). Cold hardiness is the result of complex Nnadozie Oraguzie physiological mechanisms involving many Department of Horticulture, Irrigated Agriculture, Research and Extension cellular and whole plant details. Moreover, Center, Washington State University, 24106 N Bunn Road, Prosser, WA winterhardiness is affected not only by toler- 99350 ance to cold but also by tolerance to other factors such as frost, water logging, freeze– Armin Saed-Moucheshi thaw cycles, and diseases (Steponkus, 1979). Department of Crop Science and Plant Breeding, School of Agriculture, Knowledge of the hardiness of the genetic Shiraz University, Shiraz, Iran stock to winter freezing is critical to the success of tree fruit improvement programs Additional index words. diallel crossing, freezing, cold injury, heritability and for selecting and breeding for improved Abstract cold hardiness. Cold hardiness evaluation can . The development of cultivars with broader climatic adaptation has recently be assessed by examining cold injury after become the objective of most fruit breeding programmers. Regarding the importance of natural frost events in field trials, although genetic control of cold hardiness as an influential characteristic for pomegranate and there are several limitations to screening lacking studies in this area, the genetic control of cold hardiness in pomegranate using methods relying on natural frost events for a partial mating scheme was studied. Five parents, including ‘Rabab Post Ghermez cold hardiness measurement. First, field eval- Neyriz’, ‘Malas Yazdi’, ‘Poost Sefid Dezful’, ‘Malas Pishva Varamin’, and ‘Poost Nazok uation is typically established only for the Torosh Abarkuh’ with different cold hardiness capability were screened following a cold short term on relatively mild, productive hardiness test in the laboratory and an evaluation of cold injury after natural freezing places which rarely receive damaging freez- events in the field. The five screened cultivars were crossed in half-diallel crossing scheme ing. Second, the effects of infrequent frosts with a total of 10 crosses in the Spring of 2014. Cold hardiness of the parent cultivars and may be confounded with injury due to other the F1 progenies were investigated using the electrolyte leakage (EL) method. Results causes. Third, the incidence, timing, and showed that both general combining ability (GCA) and specific combining ability (SCA) intensity of frosts are not uniform across the were statistically significant. The hardiest parent (‘Poost Nazok Torosh Abarkuh’) test place (O’Neill et al., 2001). showed the largest positive GCA effect (1560.59) for winter survival, suggesting that this The evaluation of cold hardiness under parent is capable to produce tolerant offspring with high breeding values in crossing controlled conditions in a freezer (artificial programs. The significant SCA in this study suggests that specific crosses should be freezing testing) is a common test to assay targeted to produce highly capable offspring. Cross between ‘Poost Nazok Torosh plant tissue samples for cold injury (Burr Abarkuh’ and ‘Malas Pishva Varamin’ showed high value for SCA (1661.74), indicating et al., 1990). In this method, simple and capability for production of tolerant offspring to the cold condition. Furthermore, high inexpensive measurement of cold hardiness broad-sense heritability (0.70) and moderate narrow-sense heritability (0.45) for cold can be carried out for large number of plant hardiness indicate that a reasonable progress could be made in improvement of this trait samples (O’Neill et al., 2001). Ghasemi through conventional breeding. Soloklui et al. (2012) reported that EL mea- surement and tetrazolium stain test after controlled freezing allowed them to discrim- Pomegranates are presumed to have orig- considerable interest in growing pomegran- inate among pomegranate cultivars for freez- inated in the Middle East (Persia, e.g., Iran) ate trees in tropical, subtropical, and sub- ing tolerance. O’Neill et al. (2001) reported and Southeast Asia (including Turkmenistan temperate regions of the world, including that assaying for cold hardiness at the seed- and Afghanistan), areas with relatively cold southern Asia, Africa, and Europe, particu- ling stage has advantages over testing an winters and hot summers (Castle et al., 2011). larly, in countries such as Iran, India, Turkey, adult tree. The seedling tests require less Iran is considered to be one of the major Afghanistan, Spain, Egypt, and other parts of space and time than field assays and provide producers (Holland et al., 2009). There is North Africa, China, Italy, France, and the more uniform test conditions, resulting in United States. Pomegranate consumption has a greater statistical precision and cost- increased recently because of studies that effectiveness. Received for publication 7 Dec. 2017. Accepted for confirm that pomegranate may improve cer- Earlier studies have shown that the ge- publication 11 Feb. 2018. tain features of human health resulting from netic control of cold hardiness is very com- We would like to thank Mohamadreza Vazifeshenas, the high antioxidant content of its juice and plex and mostly polygenic (Snape et al., Agriculture and Natural Resources Research Center peel and possession of properties which pre- (ANRRC), Yazd, Iran, for his supports and assis- 1997). Generation means analysis revealed tance regarding the crossing experiment of this study vent cancer and cardiovascular diseases that cold hardiness is a quantitative trait in the Yazd. (Fuhrman and Aviram, 2006). Pomegranate controlled largely by additive gene effects 1Corresponding author. E-mail: agharghani@ is a natural out-crosser, the seeds germinate and, to a lesser extent, the dominance gene shirazu.ac.ir. well and also is easily propagated by cutting effects, with cold sensitivity appearing to be HORTSCIENCE VOL. 53(4) APRIL 2018 427 partially dominant (Sanghera et al., 2011). at the main Iranian pomegranate collection in Cold hardiness measurement. One-year- Numerous studies have shown that cold Yazd, Yazd Province, Iran. old shoots (10 cm length) of asexually hardiness is inherited in an additive manner The anthers from hermaphrodite flowers propagated parent plants and the F1 seed- and progenies are intermediate between the were collected and placed on a filter paper lings were collected on 16 Jan. 2015. The parents, in both herbaceous and woody crops and after 24 h, the pollen was collected and samples were wrapped in a wet paper, (Tang, 2002). Cold hardiness could be stored in a glass vial. The stamens of un- sealed in plastic bags, and kept at 5 °C explained adequately by a simple additive– opened hermaphrodite flowers were carefully during transportation from the field to the dominance model of gene function, although removed with forceps and the pollens were laboratory. The shoots were washed with two epistatic models involving additive– applied to the female parent with a paint deionized water. One-centimeter-long seg- additive and dominance–dominance interac- brush. Pollinated flowers were immediately ments were cut and placed in 50-mL plastic tions also fit the data (Arora et al., 2000). covered with cheesecloth bags to prevent tubes. One milliliter of deionized water was Genetic studies on winterhardiness of pollen contamination. Fruits were harvested added to each sample for immediate ice pomegranate are limited. A review of the at commercial maturity in Oct. 2014. This formation. The tubes were transferred to literature on temperate fruit crops shows that part of the experiment (crossing program) a freezing chamber and exposed to low heritability estimates have been generated for was carried out at the Agricultural and temperatures. The cooling rate was 2 °C·h–1, several aspects of freezing tolerance in a few Natural Resources Research Center, located whereas freezing treatments were –6, –9, fruit crops (including plum, peach, blueberry, between long. 50°11#E and lat. 34°59#Natan –12, –15, –18, –21, –24, –27, and –30 °C. and apple) and the values reported are mod- altitude of 1145 m from the mean sea level at The samples were kept at given treatment erate to high (Arora et al., 1992; Ashworth the center of Iran. The hybrid seeds (F1 temperatures for 1 h and then transferred