TARIM BILIMLERI DERG
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S
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Journal of Agricultural Sciences
Cilt
7
Say
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Volume /
Number
Sahibi
Ankara Üniversitesi Ziraat Fakültesi Ad
ına
Prof.Dr.Yetkin GÜNGÖR
Dekan
Yayın Kurulu
Prof.Dr.A.Hamdi ERTAŞ
Prof.Dr.Nilgün HALLORAN
Prof.Dr.Ramazan ÖZTÜRK
Doç.Dr.M.Fatih SELENAY
Doç.Dr.Nevin AKPINAR
B
İ
L
İ
MSEL DANI
Ş
MA KURULU*
Nazimi AÇIKGÖZ Y.Sabit AĞAOĞLU Ünal ALTINBAŞ M.Faruk ALTUNKASA Mehmet APAN İbrahim K ATAKİŞİ Hülya ATIL Veysel AYSEL Ahmet CANBAŞ Mehmet Ali CANYURT
ÇELİKKALE İbrahim ÇIFTÇI Muammer ERDEM M.Ziya FIRAT M.Aydm GÜNEY Zeki KARA Lami KAYNAK Galip KEÇECİOĞLU Tahsin KESİCİ Süleyman KODAL Kayıhan Z. KORKUT Serpil KORNOŞOR A.Halim ORTA Hüseyin ÖĞÜT Zeki ÖZER Yunus PINAR Şafak POLATSÜ Gökhan SOYLEMEZOĞLU Yıldırım SÖZEN İsmet ŞAHIN Vedat ŞENİZ Süleyman TABAN Alaettin TAYSUN Seval TOROS Rahmi TÜRK Huriye UYSAL Lean ÜLGER Poyraz ÜLGER Hüseyin VURAL S.Rıfat YALÇIN Oktay YEĞEN Osman YILDIRIM M.Birkan YILDIRIM
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Ankara Üniversitesi Ziraat Fakültesi-Ankara Akdeniz Üniversitesi Ziraat Fakültesi-Antalya Ankara Üniversitesi Ziraat Fakültesi-Ankara Ankara Üniversitesi Ziraat Fakültesi-Ankara
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Tar
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m Bilimleri Dergisi*
Ankara Üniversitesi Ziraat Fakültesi Halkla
İ
li
ş
kiler ve Yay
ı
n Ünitesi
06110 D
ış
kap
ı
-ANKARA
E-mail: halklail@agri.ank.ara.edu.tr
ISSN: 1300-7580
Dizgi ve Bask
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: Ankara Üniversitesi Ziraat Fakültesi Halkla
İ
li
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kiler ve Yayan Ünitesi
*) Ocak, nisan, temmuz, ekim aylar
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nlan
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r.
Tar
ı
m Bilimleri Dergisi 2001
7
(1) 1-176
İ
Ç
İ
NDEK
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LER
CONTENTS
DEMİR, I., M. ÖZÇOBAN, The Effects of Combinations of Temperature and Seed Moisture Treatments on Hardseededness in Okra
Bamyada Sert Kabukluluk Üzerine Tohum Nemi ve Sıcaklık Uygulamalarının Etkisi (Afterripening) 1-4
GÜNER, M., İ. GEZER, Kayısı Hasatında Bir El Silkeleyicinin Bazı Parametrelerinin Belirlenmesi
Determination of Some Parameters of Hand Shaker in Apricot Harvesting • 5-8
KAYA, M., Ekin Yapraksülüğü, Oulema melanopus (L.) (Coleoptera: Chrysomelidae)'un Biyolojisi Üzerine Araştırmalar
Investigations on the Biology of Cerael Leaf Beetle, Oulema melanopus (L.) (Coleoptera:Chrysomelidae) 9-14
AKÇORA, A., S. PULATSÜ, Sakaryabaşı Batı Göleti'nin Besin Düzeyine Sedimentin Üstündeki ve Sediment Gözenek Suyundaki Fosforun Etkisi
The Effect of Overlying and Porewater Phosphorus on the Trophic Level of Sakaryabaşı West Pond 15-19
GÖKKAYA, Z., S. PULATSÜ, Sakaryabaşı Doğu Göleti'nin Bazı Su Kalite Parametrelerinin Mevsimsel
Değişimi
Seasonal Changes of Some Water Quality Parameters of Sakaryabaşı East Pond 20-26
iÇ, E., F. ÖZÇELIK, A. Ö. ÖZÇELİK, Düşük Tuzlu ve Tamponlanmış Salamurada Hıyar Turşusu Fermantasyonu
Cucumber Fermentation in Low-Salt and Buffered Brine 27-33
KESKIN, R., R. ÖZTÜRK, K. SAÇILIK, Tarımsal Ürünlerin Havalandırılmasında Yığın içerisinde Oluşan Basınç Düşümlerinin Belirlenmesine İlişkin Yöntem Geliştirilmesi
The Development of New Method to Determine Pressure Drops Occurred in Bed Depth During Aeration of Agricultural
Crops 34-40
DEDE, Ö., Ş. M. KARA, Ş. DERE, Bir Diallel Melez Mısır Populasyonunda Verim ve Verim Unsurlarına İlişkin Heterosis ve Uyum Yetenekleri Analizi
Heterosis and Combining Ability Analysis for Grain Yield and Yield Components in a Diallel Maize Population 41-46
ALPASLAN, M., A. GÜNEŞ, A. İNAL, M. AKTAŞ, Akdeniz Bölgesi Seralarında Yetiştirilen Bitkilerin Beslenme Durumlarının incelenmesi I. Sera Topraklarının Verimlilik Durumları.
Nutritional Status of the Plants Grown in Mediterranean Region Greenhouses I. Fertility Status of the Greenhouse
Soils 47-55
A Phytoplankton Monitoring Study in Bivalvia Production Areas 56-62
KURUM,. E., Y. ÖZTAN, Beynam Muhafaza Ormanı ve Yakın Çevresinin Ankara Kenti Rekreasyon Sistemi Açısından Koruma-Kullanım ve Planlama ilkelerinin Saptanması Üzerine Bir Araştırma
A Research on the Determination of the Protection, Land Use and the Planning Principles of Beynam Forest and It's
Surroundings for Ankara City Recreation System 63-70
ERDAL, M., Monogerm Şeker Pancarı Populasyonlarının Geliştirilmesinde Hibrid Çeşitlerin Kullanılması
Usage of Hybrid Varieties in the Improvement of Monogerm Hybrid Sugar Beet Populations 71-74
ERPUL, G., M. R. ÇANGA, Toprak Erozyon Çalışmaları için Bir Yapay Yağmurlama Aletinin Tasarım Prensipleri ve Yapay Yağış Karakteristikleri
BIRSIN, AVCI, M., Buğdayda Farklı Azot Dozlarının Tane Verimi, Protein Oranı ve Protein Verimine Etkisi
Effect of Different Nitrogen Doses on Gi Yio!d, Protein Content and Protein Yield of Wheat
KIRKAĞAÇ, M., D. ATAY, Ot Sazanı'nın (Ctenopharyngodon idellus, Vallenciennes, 1844) Yapay Koşullarda Üretimi ve Biyolojik Ot Mücadelesinde Kullanılabilecek Büyüklüğe Kadar Yetiştirilmesi
The Reproduction of Grass Carp (Ctenopharyngodon idellus, Vallenciennes, 1844) Under Artifical Conditions and Rearing to Size that can be Utilized in Biological Weed Control
ORTA, A. H., Y. ERDEM, T. ERDEM, M. ŞENER, Trakya Bölgesinde Tarım' Yapılan Kültür Bitkilerinin Sulama Programlarının Oluşturulmasında Açık Su Yüzeyi Buharlaşmasından Yararlanma Olanakları
Relations Between Evaporation and Evapotranspiration of Some Crops in Thrace Conditions 97-104
BOZKURT, M. A., İ. YILMAZ, K. M. ÇİMRıi,,:, Kentsel Arıtma Çamurunun Kışlık Arpada Azot Kaynağı Olarak Kullanılması
The Use of Municipal Sewage Sludge as a Source of Nitrogen in Winter Barley 105-110
KÖKSAL, A. İ., Y. OKAY, N. ARTIK, B. KUNTER, Batı Karadeniz Bölgesinde Yetiştirilen Bazı Fındık Çeşitlerinde Karbonhidrat Düzeylerindeki Değişimin Enzimatik Yöntemle Belirlenmesi
Determination of the Changes of Carbohydrate Levels of Some Hazelnut Cuttivars Grown in West-Blacksea Region by
Enzymatic Methods 111-118
ÜSTÜN, A. S., S. DOLAR, Ascochyta Yanıklığı (Ascochyta rablef (Pass.) Labr.)'na Dayanımları Farklı Nohut Çeşitlerinde Oransal Su, Kuru Madde ve Prolin Miktarlanndaki Değişimler
Changes in the Relative Water Content, Dry Matter and Proline Amount in the Ascochyta Blight (Ascochyta rabiei (Pass.)
Labr.) Resistant and Susceptible Chickpea Cuttivars 119-124
DUMAN, Ü., O. YILMAZ, Toplu Konut Alanlarında Ekolojik Planlama ilkelerinin Ankara-Eryaman V. Etap Örneğinde irdelenmesi
The Ecological Planning Principles in the New Settlement Areas on the Example of Ankara -Eryaman V. Stage 125-133
ÖNEN, N., O. YILMAZ, Ankara Üniversitesi Ziraat Fakültesi Kampüslerinde Arboretum Oluşturulması Üzerine Bir Araştırma
A Research on Arboretum Formation at Ankara University Faculty of Agriculture Campus 134-141
KELEN, M., İ. DEMİRTAŞ, 5 BB ve 420 A Amerikan Asma Anaçlarının Köklenme Oranları ve Kök Kaliteleri Üzerine Farklı Köklendirme Ortamları ile IBA Dozlarının Etkileri
The Effects of Different Rooting Substrates and IBA Doses on Rooting and Root Quality in 5 BB and 420 A Grapevine
R ootstocks 142-146
ERENER, G., B. Z. SARIÇİÇEK, A. ÖZDAŞ, Bıldırcın Büyütme Yemine Değişik Düzeylerde Organik Asit Karışımı ilavesinin Besi Performansı ile Bağırsak Içeriği pH'sı Üzerine Etkileri
The Effect of Organic Acids Mixture Supplementation at Various Levels to Diets of Japanese Quails on Fattening Performance and pH of Intestinal Conten:
BAŞPINAR, E., Değişik Varyans Oranlı Normal Populasyonlardan Alınan Değişik Örnek Genişliğindeki İki Örnekte Student-t, Welch ve Ayıklanmış-t Testlerinin Uygulanması ile Elde Edilen I. Tip Hata ve Testin Gücü
Type t Error and Power of Tests When Applying the Student's-t, Welch and Trimmed-t Tests to Two Samples of Various Sizes from Normal Populations Having Various Variance Ratios
GÜLER, M., Orta Anadolu Koşullarında Makarnalık Buğdayın (Triticum durum Desf.) Farklı Gelişme Dönemlerindeki Su Stresinin Verim ve Verim Öğelerine Etkisi
lnfluence of Water Stress on Yield and Yield Components of Durum Wheat (Triticum durum Desf.) at Various Growth Stages under Central Anatolian Conditions
KARACA, G., M. F. SELENAY, Harran Ovasında Karık ve Damla Sulama Sistemlerinin Ekonomik Yönden Karşılaştırılması
Economical Comparison of Furrow and Drip Irrigation Systems in Harran Plain
147-150 151-157 158-165 166-176 84-88 89-96
TARIM BILIMLERI DERGISI 2001,7 (1), 1-4
The Effects of Combinations of Temperature and Seed Moisture
Treatments on Hardseededness in Okra
Ibrahim DEMIR' Mustafa ÖZÇOBAN1
Geliş Tarihi : 20.06.2000
Abstract: This research was conducted to fınd out the effect of temperature and moisture combination (afterripening) treatments on occurrence of hardseededness in okra. Okra seed germination (loss of dormancy and hardseededness) was increased by afterripening (temperature and seed moisture treatments) seeds at 30, 40 and 50°C, with moisture contents between 9.4 and 17.7 % for up to 28 days at 30 and 4 days at 40 and 50 °C. From the water isotherms constructed, it was found that this involves water binding region 2. Afterripening reduced percentage of hardseededness from 54 -63 % at the lowest to 15-30 % at the highest moisture contents of water isotherms.
Okra seeds, can be afterripened, at 30, 40 and 50 °C, within the range of water-binding region 2 and germination be improved.
Key Words: Okra, afterripening, hardseededness, germination, seed moisture, temperature
Bamyada Sert Kabukluluk Üzerine Tohum Nemi ve S
ı
cakl
ı
k
Uygulamalar
ı
n
ı
n Etkisi (Afterripening)
Özet: Araştırma sıcaklık ve nem kombinasyonlarının bamyada sert kabukluluğun oluşumuna etkisini belirlemek amacıyla yürütülmüştür. Bamya tohumlarının çimlenmesi (dinlenmenin ve sert kabukluluk etkisinin kırılması), %9.4 ve %17.7 nem kapsamına sahip tohumları 30°C sıcaklıkta 28 gün, 40 ve 50°C sıcaklıklarda ise 4 gün süre ile olgunlaştırılarak artırılmıştır. Kurulan su izotermlerinden bamya çimlenmesinin 2. Su bağlama bölgesini kapsamaktadır. Yapılan uygulama ile en düşük su kapsamına sahip tohumlarda sert kabukluluk %54-63 arasında değişirken,yüksek su kapsamına sahip tohumlarda %15-30 arasında olmuştur.
Bamya tohumları 30, 40 ve 50°C'de ikinci su bağlama bölgesi sınırları içinde olgunlaştırılabilmekte ve çimlenme oranları artırılabilmektedir.
Anahtar Kelimeler: Bamya, afterripening, sert kabukluluk, çimlenme, tohum nemi, sıcaklık
Introduction
Hard seed coat, coat imposed dormancy, is known phenomenon in okra which causes slow, and ununiform germination. Different methods such as acid scarification (Boyd 1985), hormone soaking (Omran et al. 1980), afterripening (Demir 1994) and combination of acid, osmoconditioning and hot water treatments (Passam and Polyzou 1997) were used to eliminate hardseededness and increase germination. Afterripening describes the loss in dormancy that gradually occurs when seeds are stored after harvest as a function of seed moisture and temperature. In general, the higher either of these factors are the more rapid is the loss in the dormancy (Ellis et al. 1985). Demir 1994 found that okra seed germination was greatly improved by afterripening treatment at 50 °C with around 10 ?/0 moisture content for up to 3 days.
Vertucci and Leopold (1984) found that there are three regions of water-binding the seed components and these help for interpretation of various biochemical processes which can occur in seeds as a function of water content. Region 1 and 2 involves nonenzymatic oxidation, while region 3 is identified as the uptake of oxygen with production of CO2 (Vertucci and Leopold 1986)
Leopold, Glenister and Cohn (1988) showed that afterripening red rice occurred between 6 and 14% moisture content which includes parts of water -binding
region 1 and 2. In okra, hardseededness as well as afterripening treatment efficiency is related to seed moisture. For example, Ellis et al. (1985) reported little or no hardseededness at 13% and above, Standifer et al. (1989) found that no hardseededness observed in those seeds that have 11% moisture and higher.
In this paper, relationship between seed moisture content and afterripening effect at three different temperatures in okra was investigated. This was also interrelated to water-binding region in water isotherm.
Material and Methods
Okra plants (Abelmoscus esculentus L.Moench cv.
Akköy) were grown on the Experimental Field of the Department of Horticulture, Faculty of Agriculture Univer-sity of Ankara in 1999. Pods were harvested 60 days after anthesis at which seed moisture declined to 7-8 % on the plant. Seeds were shelled by hand and kept at room temperature, until the experiment begins (Demir 1997).
Seeds were equilibrated to various moisture contents between 8.3% and 17.7% in sealed 500 ml containers over saturated salt solutions according to Copeland and M. McDonald (1995). These solutions were slikagel,
2 TARIM BILIMLERI DERGISI 2001, Cilt 7, Sayı 1
CaCl2, MgNO3, NaCI, KCI and water which gaye 8.3, 9.4, 10.1, 10.2, 11.7, and 17.7% seed moisture. Seeds were brought to equilibrium in a period of 15 days at 20°C. After moisture equilibration seeds of each moisture were kept at 5°C in sealed glass jars for 10 days in order to provide equilibration among and within the seeds. After that, seed moisture content (fresh weight basis) was determined by drying two samples of 2 grams each at 130°C for 2 hours. Seeds were ground before moisture content was carried out.
For each moisture content 12 samples of 100 seeds were prepared and put into the aluminium laminated foil packets. 4 samples of each stored at 30°C, 40°C and 50°C and one sample was withdrawn after 7, 14, 21 and 28 days, at 30 °C, 1, 2, 3 and 4 days at 40 and 50°C
At every sampling date, seeds were taken out and 4 replicates of 25 seeds were germinated between filter papers ( 20 cm x 20 cm) moistened with 7.5 ml of deionised water at 25 °C for 21 days. Counting was carried out twice a week. Radicle protrusion was considered as germination criterion.
At the end of the germination test, seeds which did not imbibe were considered as hard seeds and counted.
Two samples of 2 gram of seeds were incubated at each of 6 different saturated solution which are silicagel, CaCl2, MgNO3, NaCI, KCI and water. These gave about 10, 35, 52, 72, 85 and 100 relative humidity, respectively at 20 °C (Vertucci and Leopold 1984). After 12 days samples were dried (130°C, 2 hours) to determine seed moisture content.
Then moisture isotherm was constructed.
Statistical analysis was carried out by using macustat (Oregon State University, USA). Archsin transformation was used to the values and comparison were performed
by LSD.
In order to test whether dry storage alleviate hardseededness and increase germination, 5 years old seeds (1995 crop) were germinated.
To find out afterripening effect on physical structure of 5 years old seeds 10 seeds of two replicate of treated
and control seeds were weighed and imbibed in 50 ml of
deionised water at 20 °C for 24 hours. Then, fınal weight
was determinated after surfaca-dried and final weights were divided by the initial one in order to find imbibition rate.
Results
Results from Table 1 and Table 2 showed that afterripening in okra proceeded best at water contents between 9.4 and 17.7, at all three temperatures. Seeds of lower moisture contents than 9.4 had significantly lower germination percentages (p<0.05) than those of above. Regarding the period of afterripening there was no difference among 7, 14, 21 and 28 days at 30°C, 1, 2, 3 and 4 days at 40 and 50°C (Table 1 and 2). The exceptions for that were observed at the lowest seed moisture (8.3 %) at 40 and 50°C, and the highest seed moisture at 50°C.
At 50°C seeds treated with 17.7 moisture content for 2 days and longer showed significantly lower germination percentages, most likely due to the ageing. Occurrence of hardseededness was reached maximum at seeds that have 8.3 % moisture content. That was gradually declined being the lowest at 17.7 % (Table 3). In the most of cases the lower the seed moisture the higher the occurrence of hardseededness.
In order to determine the possible relationship between the range of water contents for after ripening and the status of water binding in the seeds , moisture isotherm was constructed at 6 different relative humidities, at 20°C (Figure 1). It described double-sigmoid curve which is characteristic of orthodox species (desiccation tolerant). From figure 1, it could be mentioned that water contents at values afterripening can occur mostly at water region 2 and beginning of region 3 in okra. If temperature is above at 40°C, it is rather good to be used water region 2 which contain seeds with 9.4 and 17.7 % .Storing seeds in air-dried stored did not alleviate hardseedednes and increase germination percentage of okra seeds. Full-mature 5 years old seeds with 8% moisture content showed 40% germination. Whereas, fresh harvested (1999 crop) seeds germination was 43 % at the same moisture content (Table 3),
Table 1. Germination percentage of afterripened okra seeds by using different temperature and moisture contents (%) combinations with different periods (days)
Seed m.c.(%)
Temperature and treatment period (day)
30°C 40°C 50°C
7 14 21 28 LSD 1 2 3 4 LSD 1 2 3 4 LSD
8.3 40Aa 34Aa 35Aa 39Aa 7.9 36Ab 35Ab 31Ab 8.0Aa 10,1 21Aa 25Aab 33Bab 36Ab 7.2
9.4 58Bb 44Aa 58Ba 60Bb 8.3 43ABa 53Ba 45Aba 45 Ba 12.6 46Bb 53BCb 54Ab 59Bb 9.6
10.1 60Ba 60Aa 65Ba 67 Ba 11.6 47ABCa 58Ba 54 Ba 59CBa 8.8 58CBa 56Ca 53Ca 65Ca 13.1
10.2 64Ba 64Ba 63Ba 64 Ba 9.7 49ABCa 52Ba 48Aba 62Ca 9.8 64Ca 47Bca 54Ca 63Ca 12.5
11.7 70Ba 65Ba 66Ba 64 Ba 10.0 57BCa 58Ba 45Aba 58CBa 10.5 58Cba 65Ca 54Ca 59CBa 11.0
17.7 70Ba 66Ba 67Ba 71 Ba 9.7 61Ca 47ABa 55 Ba 62Ca 10.9 50CBb 35ABa 34Ba 29Aa 5.6
LSD 10.1 6.8 10.1 9.7 10.0 9.4 11.8 8.5 8.5 8.5 12.1 10.6 7.5
Means with different letter are signif cantly different( p<0.05) according to Duncan's Multiple Range Test. Big letters show difference in the column, small letters in row.
18,0 16,0 14,0 12,0
c4.
ı
o,o
E aı tv co 35 52 72 eGFhlative Humidity (Y4 8,0 6,0 4,0 2,0 0,0 23 100
DEMİR, İ. ve M. ÖZÇOBAN "The effects of combinations of temperature and seed moisture treatments on hardseededness in okra" 3
Table 2. Percentages of hard seeds in afterripened okra seeds ( MeanstSE) Seed m.c.(%) Hard seeds(%) 30°C 40°C 50° C 7 14 21 28 1 2 3 4 1 2 3 4 8.3 57±9.4 63±8.8 59±9.4 54±6.9 60±9.8 64±13.4 61±16.7 85±8.2 72±5.6 74±2.5 63±7.9 63±5.03 9.4 37±17.4 48±5.6 37±6.0 33±11.4 54±11.5 44±16.3 50±21.7 52±7.3 51±8.2 39±10.5 90±5.1 48±11.71 10.1 41±18.2 33±8.2 29±3.8 24±13.0 51±14.0 42±8.3 40±12.6 38±7.6 38±10.0 43±18.0 42±13.6 33±8.25 10.2 37±6.0 30±10.5 30±4.0 29±15.1 49±10.0 41±15.1 47±7.5 34±6.9 33±13.2 45±6.0 43±28.3 31±11.44 11.7 26±14.0 30±12.4 26±6.9 30±4.0 41±13.6 37±10.0 49±6.0 40±5.6 36±13.4 35±15.4 42±12.8 39±8.25 17.7 19±10.0 30± 2.3 15±6.8 24± 4.6 37±10.5 37±8.2 41±12.8 33±10.5 36±15.3 26± 7.6 35±6.8 28±8.64
Table 3. Seed germination and imbibition rate of differentially harvested 5 and 1 year old okra seed lots DAA
36 39 43 46 50 58 LSD
Germination (5 years old) 16a 66d 18ab 20ab 28ab 40c 43 10.6
imbibition rate (%) 17 11 9 15 9 6 7 -
*1 year old seed germination DAA: Days after anthesis.
Figure 1. Water isotherm of okra seeds constructed from saturated salt solutions
Imbibition rate of 5 year and 1 year old seeds was similar which shows that air-dried storage did not decrease hardseededness (Table 3).
Discussion
After ripening, describes the loss in dormancy that gradually occurs when seeds are stored after harvest and the rate of loss can be influenced by both the temperature and the moisture content. In general the higher either of these factor are the more rapid is the loss in dormancy.
In okra coat-imposed dormancy , hardseededness is a common physiological phenomenon and prevents germination even though water is extremely available. Some of the former studies related that to seed moisture content of seed (Ellis et al. 1985, Standifer et al. 1989) and developmental stage and drying rate (Demir 1997). Ellis (1985) and Standifer et al. (1989) reported that hardseededness does not occur above 13 and 11% of seed moisture respectively. However, in commercial practice, okra seeds dried down to 7-8% moisture content on the mother plant at harvest period (Demir 1994).
There are number of ways to use for attempting to improve okra germination and overcome hardseededness such as acid scarification (Lancon and Klassou 1988), hot water immersion (Onwueme 1975), combination of acid osmoconditioning and hot water (Passam and Polyzou 1997) and after ripening treatments (Demir 1994).
After ripening treatments are based on combination of temperature and seed water content (Ellis et al.1985). In this experiment, the best response from after ripening treatment was taken from seeds between 9.4 and 17.7%.
From water isotherms, we fınd that the range of
optimal water contents is water binding region 2. Leopold, Glenister and Cohn (1988) found that in red rice the best response to after ripening was obtained when seeds are treated between 6 and 14% at 22 °C which belongs to water binding region of 1 and 2. That region of water isotherms is involved non-enzymatic oxidative reactions in seed (Priestley 1986). The case in okra indicates that, oxidative metabolism starts in seed while treatment is on, since beneficial seed moisture contents are approaching to region 3 which was shown that oxidative metabolism take place in several species (Vertucci and Leopold 1986).
After ripening occurs in numerous species in dry-state, such as Brassica (Tokumasu 1971) and Avena fatua (Quail and Carter 1969). However, this does not take place in okra , germination percentage of 5 years old seeds stored at room temperature showed similar values with 1 year old one (Table 3).
How could high temperature and seed moisture effect the seed coat and allow germination? Egley (1976) found in prickly sida seeds that high temperature and seed moisture fluctuation caused expansion and contraction of cells çhalasal region and influence loss of impermeability. He also pointed out that loss of impermeability in nature manipulate by fluctuation in temperature and seed moisture.
Our finding also showed that treated okra seeds with 24 hours imbibed more water than no-treated ones, which implies damaging effect on coated cells by treatment.
4 TARIM BILIMLERI DERGISI 2001, Cilt 7, Sayı 1
Ellis et al. (1985) pays attention to after ripening that, if it is used at high temperature and seed moisture contents can lead to seed ageing therefore is not recommended to gene banks. Overlapping with that suggestion, we found that treatment of 50 °C, with 17.7% seed moisture for 2, 3 and 4 days are damaging to okra seed viability.
Afterripening treatments decreased number of
hardseededness greatly, and its related to seed moisture content too. The maximum hardseededness obtained seed treated with 8.3 % moisture content.
In all these seeds hardseededness was above 50%. This was in agreement with result of some former studies (Ellis et al. 1985, Standifer et al. 1989).
Passam and Polyzou (1997) suggested acid and hot water treatment in order to eradicate hardseedednes in okra, however both treatment require high laborous work and moreover drying after treatment. However, after ripening is much easier and less laborous.
It appears that okra seed germination can be improved after ripening treatments and decreased hardseededness. The best advantages is obtained from seeds treated between 9.4 and 17.7 % of seed moisture. Likely that this happened through the as influence on oxidative metabolism as well as physical structure of seed coat especially around chalasal region.
References
Copeland, L. O. and M.B. McDonald, 1995. Seed Science and Technology .Chapman and Hall New York.
Demir, İ. 1994. Hardseededness and afterripening effect in okra.ISTA/ISHS Symposium Technological Advances in Variety and Seed Research. 31 May-3 June 1994.Wageningen/ Netherlands.
Demir, İ. 1997. Occurrence of hardseededness in relation to seed development in okra .Plant Varieties and Seeds 10,7-13. Egley, G. H. 1987. Water-impermeable seed coverings as
barriers to germination. Recent Advances in the Development and Germiantion of Seeds ( Ed.R.B.Taylorson) Plenum Press New York.pp 207-222.
Ellis, R. H., T. D. Hong and E. H. Roberts, 1985. Handbook of seed Technology for Genebanks Vol.11 Compendium of specific germination information and test recommendations. IPGRI.
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Onwueme, I. C. 1975. Enhancement of okra seedling growth and emergence by heat stress conditions. Journal of Agricultural Science,Cambridge 85,233-239.
Priestley, D. A. 1986. Seed Ageing Comstock Publish.Assoc. NY.304 page.
Quail, P. H and O. G. Carter, 1969. Dormancy in seed of Avena Fatua Aust. J.Agric. Res.20, 1-11,
Tokumasu, S. 1971. Effect of dry and wet storage upon seed dormancy in cruciferous vegetables. J.Japan Soc. Hortic.Science 40,23-28.
Vertucci, C. W. and A. C. Leopold, 1984. Bound water in soayabean seed and its relation to respiration and imbibitional damage. Plant Physiology 75,114-117
Vertucci, C. W. and A.C. Leopold, 1986. Physiological activities associated with hydration level in seeds In Membranes ,Metabolism and Dry organisms( A.C.Leopold ed.) pp.35- 49.Cornell Univ.lthaca New york.
