Punica granatum L.

Hormone Physiology of Preharvest Fruit Cracking in Pomegranate (Punica granatum L.) C. Yılmaz Alata Horticultural Research Institute 33740 Erdemli-Mersin Turkey

A.I. Özgüven Çukurova University, Agricultural Faculty Horticultural Department 01330 AdanaTurkey

Keywords: pomegranate, fruit cracking, GA3, IAA, ABA Abstract The aim of this experiment was an examination of the plant hormone physiology of preharvest fruit cracking in pomegranate (Punica grantum L.). The experiment was carried out with the cultivars ‘İzmir 10’, ‘İzmir 15’, ‘İzmir 16’, ‘İzmir 23’, ‘İzmir 26’, ‘Silifke Aşısı’ and ‘Hicaz’, 4 replicates of each, at the research and experimental field of the Agricultural Faculty of Çukurova University, Turkey, in 2001 and 2002. Abscisic acid (ABA), indole 3- acetic acid (IAA) and gibberellic acid (GA3) contents were measured in the fruit peel of all the cultivars. At the same time, the yield and percent fruit cracking for all cultivars have been determined. The highest fruit cracking rates were in İzmir 10 and Silifke aşısı, the lowest was in İzmir 16 in 2001, while the highest was in İzmir 15 and the lowest was in İzmir 16 in 2002. The ABA content of the peel was generally higher in cracked fruit than in the peel of healthy (non-cracked) fruit. INTRODUCTION Turkey is one of the native lands of the pomegranate. It is spread over and grown in every area, such as in the coastal and the mountainous areas up to an altitude of 1000 m. Pomegranate is mainly grown, however, in the Aegean, Mediterranean and Southeastern Anotolia regions. Its cultivation has increased in the Southern Anatolia regions with the aid of a GAP project in recent years (Özgüven, 1998). Total pomegranate production of Turkey reached approximately 60 thousand tons in 2001(Anonymous, 2002). Turkey is an important world exporter of pomegranates (Özgüven and Yılmaz, 2000). The main physiological disorder of pomegranate is fruit cracking which is believed to result from the pressure of the rapidly expanding arils on the stretched peel (Yılmaz, 1999). The damage can sometimes affect most of the yield (Blumenfeld et. al., 2000). Currently very few studies have been carried out aimed at explaining this complex phenomenon physiologically. The aim of this experiment was to examine the plant hormone physiology of preharvest fruit cracking in pomegranate (Punica grantum L.). MATERIALS AND METHODS The experiment was carried out with 7 pomegranate cultivars (‘İzmir 10’, ‘İzmir 15’, ‘İzmir 16’, ‘İzmir 23’, ‘İzmir 26’, ‘Hicaz’ and ‘Silifke aşısı’) all of which were 5 years old (in 2001) in 4 replicates of randomized complete blocks during two years (2001 – 2002) in the Horticultural Department of Çukurova University. The pomegranate trees were pruned to a single trunk tree, irrigated by furrow irrigation and not fertilized. Yield (kg/tree) and the percentage of cracked fruits among the seven pomegranate cultivars were determined at harvest. The contents of GA3 and ABA in cracked and healthy (non-cracked) fruit peels were extracted (Takahashi and Yamaguchi, 1986) and analyzed in reversed phase HPLC. In the GA3 and ABA analysis, an HP1100 system, Hypersil ODS C18 column (250 x 4.6 mm ID) and DAAD detector were used. ABA contents in cracked and healthy fruit peels were analysed by ELISA (Weiler, 1982). In the experiment, the data was analyzed using the SAS statistical program. Proc. Xth IS on Plant Bioregulators in Fruit Eds. A.D. Webster and H. Ramirez Acta Hort. 727, ISHS 2006

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RESULTS Fruit Cracking The percent fruit cracking for the 7 pomegranate cultivars in 2001 and 2002 are given in Table 1. Fruit cracking in 2001 was higher than that in 2002, except for the cv. ‘İzmir 15’. In the first year, when the highest fruit cracking rates were determined with ‘İzmir 10’ (46.3%) and ‘Silifke aşısı’ (43.9%), the lowest rates were recorded on ‘İzmir 16’ (1.0%). In the second year, the highest fruit cracking rates were recorded on ‘İzmir 15’ (33.4%) and ‘İzmir 10’ (23.2%), but there was no fruit cracking on ‘İzmir16’ (0.0%). Yield

The yields (kg/tree) of the 7 pomegranate cultivars in 2001 and 2002 are shown in Table 2. There were no significant differences between the yields of the cultivars in either year. In the first year, the highest yield was produced by ‘İzmir 10’ (7.64 kg/tree) and the lowest by ‘İzmir 16’ (3.64 kg/tree). In the second year, the highest yield was produced by ‘İzmir 15’ (8.77 kg/tree) and the lowest by ‘İzmir 16’ (3.53 kg/tree) and ‘Silifke aşısı’ (3.58 kg/tree). The Content of GA3 in Fruit Peel The contents (ng.g-1) of GA3 in cracked and healthy fruit peels of the 7 pomegranate cultivars in 2001 and 2002 are shown in Table 3. There were no significant differences between the content of GA3 in cracked and healthy fruit peel, between years or between cultivars. The Content of IAA in Fruit Peel The contents (ng.g-1) of IAA in cracked and healthy fruit peels of 7 pomegranate cultivars in 2001 and 2002 are shown in Table 4. The healthy fruit peel had higher IAA content than the cracked fruit peel in both years. The first year’s fruit peel was higher in IAA content than that of second year’s fruits’ peel. The highest IAA content was found in ‘İzmir 23’ (37.1 ng.g-1) and the lowest in ‘İzmir 15’ (29.5 ng.g-1). The Content of ABA in Fruit Peel The contents (ng.g-1) of ABA in cracked and healthy fruit peels of 7 pomegranate cultivars in 2001 and 2002 are shown in Table 5. There were significant differences between ABA contents of cracked and healthy fruit peels, between years and between cultivars. The peel from cracked fruits had higher ABA contents than that of healthy fruits in both years. The highest ABA contents in peel were recorded for the cvs ‘Hicaz’ and ‘İzmir 26’, the lowest was in ‘İzmir 15’. DISCUSSION The fruit cracking rates varied between 0.0% and 46.3%, depending upon cultivars and years. Although there was severe fruit cracking in cultivars in the first experimental year, in the second year fruit cracking rates were mostly decreased by half (except for ‘İzmir 16’). Only ‘İzmir 15’ showed increased rates of cracking in the second year. Özgüven et al. (1997) have also examined fruit cracking rates on these cultivars and recorded 20.1% on ‘İzmir 10’, 20.6% on ‘İzmir 15’, 0.9% on ‘İzmir 16’, 13.1% on ‘İzmir 23’, 21.0% on ‘İzmir 26’, 20.6% on ‘Hicaz’, and 24.7% on ‘Silifke aşısı’. All of these cultivars have moderate rates of fruit cracking except for ‘İzmir 16’, which has the lowest susceptibility to fruit cracking. All the cultivars compared in the experiment, except ‘İzmir 16’ were considered to be productive. There were no significant differences in the contents of GA3 in cracked and healthy fruit peel, or in different years or cultivars. It was shown that cracked fruit peel had higher ABA and lower IAA contents than that of healthy fruits. In the first year, when there was severe fruit cracking, ABA content was higher, and conversely in the next year 546

which had lower fruit cracking, ABA content was lower. Sharma and Dhillon (1998) noted that there were higher ABA contents in the aril and peel of cracked litchi fruit than that of healthy fruits. Josan, et. al. (1998) reported that GA3 and NAA treatments decreased fruit cracking in lemon and that ABA content was higher in control fruits, which had higher fruit cracking ratio. These effects are believed to result from any stress factor (water, heat, excess light) which affects the fruits ACKNOWLEDGEMENTS This project was funded as TOGTAG-3015 by TUBITAK Literature Cited Anonymous. 2002. T.C. Governmental Statistical Institute Bulletin, Ankara. Blumenfeld, A., Shaya, F., and Hillel, R. 2000. Cultivation of Pomegranate. Options Mediterraneennes, Serie A: Seminaires Mediterraneennes Numero 42:143-147. Josan, J.S., Sandhu, A.S. and Zora, S. 1997/1998. Effect of Plant Growth Regulators Sprays on the Endogenous Level of Phytohormones and Splitting of Lemon Fruit. Recent Horticulture, 4:19-21. Özgüven, A.I. 1998. World Production Status of Pomegranate (Punica granatum L.). 2nd MESFIN Meeting on Plant Genetic Resources, 5-8 August, 1997, Madeira, Portugal. 247-265. Özgüven, A.I. and Yılmaz, C. 2000. Pomegranate Growing in Turkey. Options Mediterraneennes, Serie A: Seminaires Mediterraneennes Numero 42:41-48. Özgüven, A.I., Çetiner, S., Ak, B.E. and Yılmaz, C. 1997. The Investigations on Adaptation of Different Pomegranate Varieties in Southeast Anatolia Region. Çukurova University Faculty of Agriculture Southeastern Anatolia Project Agricultural Research and Development Project Package. II. Stage Final Report (1993-1997). Ç.Ü. General Publication Number: 205, GAP Publication Number: 117, p. 21, December 1997, Adana. Sharma, S.B. and Dhillon, D.S. 1998. Endogenous Levels of Abscisic Acid in relation to Fruit Cracking in Litchi (Litchi chinensis Sonn.). Agricultural Science Digest, India, 8(1):55-58. Takahashi N. and Yamaguchi, I. 1986. Analyses of Endogeneous Plant Hormone Levels Throughout the life of Higher Plant. Acta Hort. 179:47-71. Weiler, E.W. 1982. An Enzyme-immunoassay for cis –(+)-Abscisic Acid. Physiol. Plant. 54:510-514. Yılmaz, C. 1999. Bazı Bitki Besin Maddeleri, Gibberellik Asit ve Pinolene Uygulamalarının Narda Verim, Meyve Kalitesi ve Çatlaması Üzerine Etkileri. Msc. Thesis, Çukurova Üniversitesi Fen Bilimleri Enstitüsü, 125 p., (unpublished).

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Tables Table 1. Fruit cracking among 7 pomegranate cultivars grown in Adana-Turkey in 2001 and 2002. Cultivars İzmir-10 İzmir 15 İzmir 16 İzmir 23 İzmir 26 Hicaz Silifke aşısı Mean LSD%5 (cultivar 2001)= 16.37 LSD%5 (mean cultivar)= 10.01

Fruit Cracking Rates (%) Years 2001 2002 46.3 23.2 9.1 33.4 1.0 0.0 29.8 11.9 15.0 3.3 14.3 11.1 43.9 8.3 22.8 a 13.0 b LSD%5 (cultivar 2002)= 13.14 LSD%5 (mean year)=5.35

Mean 34.8 a 21.3 abc 0.5 d 20.9 abc 9.2 cd 12.7 bcd 26.1 ab

Table 2. Yields of the 7 pomegranate cultivars grown in Adana-Turkey.in 2001 and 2002. Cultivars 2001 7.64 6.50 3.64 7.29 6.18 6.43 7.23 6.42 2.38

İzmir 10 İzmir 15 İzmir 16 İzmir 23 İzmir 26 Hicaz Silifke aşısı Mean LSD%5

LSD%5 (year) = n.s.

Yield (kg/tree) Years 2002 6.46 8.77 3.53 8.30 7.88 4.62 3.58 6.16 3.38

*n.s.: non significant

Mean 7.05 a 7.64 a 3.59 b 7.80 a 7.03 a 5.53 ab 5.41 ab 2.16

Table 3. The content of GA3 in cracked and healthy (non-cracked) fruit peels of 7 pomegranate cultivars grown in Adana-Turkey in 2001 and 2002.

Cultivars İzmir 16* İzmir 10 İzmir 15 İzmir 23 İzmir 26 Hicaz Silifke aşısı Mean Mean

GA3 content (ng.g-1) Years 2001 2002 Cracked Healthy Cracked Healthy 381 384 443 491 448 365 385 453 367 322 374 344 371 554 378 452 437 442 410 385 417 407 485 399 531 366 412 421 429 409 417 419

LSD%5 (2001 cracked)=n.s. LSD%5 (2002 healthy)=n.s LSD%5 (mean cultivar)=n.s. c.s.: Cracking status

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Mean

LSD%5 (2001 healthy)=n.s. LSD%5 (2002 cracked)=n.s. LSD%5 (2001 c.s.)=n.s. LSD%5 (2002 c.s.)=n.s. LSD%5 (mean c.s.)=n.s. LSD%5 (mean year)=n.s. * There was not enough cracked fruit to analyze

382 437 382 411 427 405 445 418

Table 4. The content of IAA in cracked and healthy (non-cracked) fruit peels of 7 pomegranate cultivars grown in Adana-Turkey in 2001 and 2002. IAA content (ng.g-1) Years Cultivars 2001 2002 Mean Cracked Healthy Cracked Healthy İzmir 16* 46.0 31.1 38.6 İzmir 10 34.9 39.3 25.4 28.0 31.9 ab İzmir 15 35.7 30.4 29.7 22.2 29.5 b İzmir 23 40.3 42.2 31.4 34.7 37.1 a İzmir 26 36.1 32.9 30.0 29.6 32.1 ab Hicaz 27.3 48.2 23.0 34.6 33.3 ab Silifke aşısı 35.3 42.6 31.5 31.2 35.1 ab Mean 34.9 b 39.3 a 28.5 b 30.1 a Mean 37.1 a 29.3 b 33.2 LSD%5 (2001 cracked)=6.32 LSD%5 (2001 healthy)=6.22 LSD%5 (2002 cracked)=n.s. LSD%5 (2002 healthy)=n.s LSD%5 (2001 c.s.)=2.46 LSD%5 (2002 c.s.)=n.s. LSD%5 (mean cultivar)=3.94 LSD%5 (mean c.s.)=2.27 LSD%5 (mean year)=2.27 c.s.: Cracking status * There was not enough cracked fruit to analyze

Table 5. The content of ABA in cracked and healthy (non-cracked) fruit peels of 7 pomegranate cultivars grown in Adana-Turkey in 2001 and 2002. Cultivars İzmir 16* İzmir 10 İzmir 15 İzmir 23 İzmir 26 Hicaz Silifke aşısı Mean Mean

Cracked 149 100 133 170 185 117 142 a

LSD%5 (2001 cracked)=41.2 LSD%5 (2002 healthy)=18.6 LSD%5 (mean cultivar)=3.94 c.s.: Cracking status

2001

131 a

ABA content(ng.g-1) Years Healthy 78 115 89 137 125 124 126 119 b

Cracked 125 80 107 93 90 93 98 a

2002

93 b

Healthy 91 72 71 91 101 112 75 87 b

Mean 85 115 a 85 b 117 a 122 a 128 a 103 ab 112

LSD%5 (2001 healthy)=n.s. LSD%5 (2002 cracked)=n.s. LSD%5 (2001 c.s.)=19.5 LSD%5 (2002 c.s.)=8.8 LSD%5 (mean c.s.)=2.27 LSD%5 (mean year)=2.27 * There was not enough cracked fruit to analyze

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