Turkish Journal of Agriculture and Forestry Turk J Agric For (2015) 39: 227-233 http://journals.tubitak.gov.tr/agriculture/ © TÜBİTAK Research Article doi:10.3906/tar-1404-133

Effect of dipsaci Kühn, 1857 (: ) on yield in Province,

1, 2 3 Elif YAVUZASLANOĞLU *, Abdullah DİKİCİ , İbrahim Halil ELEKCİOĞLU 1 Department of Plant and Production, Technical Sciences Vocational School, Karamanoğlu Mehmetbey University, Karaman, Turkey 2 Institute of Science, Karamanoğlu Mehmetbey University, Karaman, Turkey 3 Department of Plant Protection, Faculty of Agriculture, Çukurova University, , Turkey

Received: 28.04.2014 Accepted: 17.11.2014 Published Online: 06.04.2015 Printed: 30.04.2015

Abstract: This study was conducted to investigate the effect of the stem and Kühn (Tylenchida: Anguinidae) on yield parameters of some onion varieties in Karaman Province, Turkey. Experiments were established in a naturally infested onion field during two consecutive years (2012–2013). Nematode population development was followed at the beginning and end of the experiment. The reproduction rate was also calculated. Onion yield and the representative average diameter and length of the onion cultivar were determined. Yield parameters of six onion varieties were compared on nematicide-treated and untreated control plots in the experiments. Nematode populations significantly decreased in the nematicide-treated plots at the beginning of the experiment during both growing seasons. The average population density of D. dipsaci was 104 individuals/100 g dry soil in the first year and 68 individuals/100 g dry soil in the second year of the experiment. The initial and final nematode populations were significantly positively correlated with Betapanko, Pan88, and Local variety1 cultivars, whereas they were negatively correlated with the Valenciana cultivar during the first year. This suggests that Betapanko, Pan88, and Local variety1 were susceptible to D. dipsaci, whereas the Valenciana cultivar could have some resistance. The overall reproduction rate of D. dipsaci was negatively correlated with initial population density and was primarily <1, which presumably represented a downward trend in nematode reproduction due to environmental conditions at the end of the experiment in September. Betapanko and Pan88 were susceptible varieties, and stem and bulb nematode caused yield losses of up to 12.93% and 15.33%, respectively; these varieties were considered intolerant. The yield of Local variety1 was positively related with initial nematode population density and it was categorized as tolerant to D. dipsaci.

Key words: Onion, stem and bulb nematode, yield

1. Introduction growing areas of Karaman (Dikici and Yavuzaslanoglu, Turkey is an important dry onion producer and the seventh 2012). The stem and bulb nematode Ditylenchus dipsaci leading producer after China, India, USA, Iran, Russian Kühn (Tylenchida: Anguinidae) is the most important Federation, and Egypt with a total production of 1.8 × nematode pest in a wide range of plants, including 6 10 t in 2012 (TÜİK, 2014). are produced in many onion, , hyacinth, , and tulip, particularly . Karaman Province, which includes in temperate regions (Potter and Olthof, 1993; Tenente, terrestrial and Mediterranean mountain climate properties 1996). Moreover, the European and Mediterranean Plant (Karaman Çevre ve Orman Müdürlüğü, 2007), contributes Protection Organization (EPPO) has placed D. dipsaci 12,657 t of dry onions or 0.0131 t/ha (2012 data; TÜİK, as no. 174 on the A2 list of phytosanitary categorization, 2014). Onions are produced in an approximately 1000-ha which is distributed locally in EPPO countries, and it is area in central villages and in the and Ayranci regulated as a quarantine pest (EPPO, 1997). districts of Karaman (2012 data; TÜİK, 2014). Crop losses differ depending on the initial nematode Plant-parasitic cause 8.8%‒14.6% crop infection level in host plants. Sturhan and Brzeski (1991) losses annually and total economic yield losses of 100‒157 billion US dollars worldwide (Nicol et al., 2011). reported crop losses of 60%‒80% in heavily infected fields. Ditylenchus spp., spp., and spp. Mennan (2001) reported that D. dipsaci caused a 65% yield were found most frequently and abundantly in the onion- loss in onion in the district of . * Correspondence: [email protected] 227 YAVUZASLANOĞLU et al. / Turk J Agric For

The aim of the present study was to investigate the effect alkaline (7.72), and no salinity problem was detected of D. dipsaci on growth and yield parameters of different (electrical conductivity: 146.7 µS/cm). The organic matter onion varieties in a naturally infested field in Karaman content of the soil was low (2.77%). Average CaCO3 and Province on the Central Anatolian Plateau of Turkey. P contents of the field soil were 20.7% and 17.9 mg/kg, respectively. 2. Materials and methods 2.2. Experimental design 2.1. Experimental site The experimental was established in a 32.5 m × 38 m area The experiment was set up in a field naturally infected with comprising 84 experimental plots. Each plot area was D. dipsaci in the Morcalı village of Karaman (37.1108°N, 11.25 m2 for onion planting, including 10 rows. Rows 33.11229°E; 1075.79 m a.s.l.) and in the same plots were each 5 m long with 25 cm between rows and 50 cm during 2012 and 2013. Ditylenchus dipsaci was identified between plots. Six commercial onion cultivars, Kantaropu, based on morphological and morphometric characters Betapanko, Valenciana, Pan88, Local variety1 (round-type (Barraclough and Blackith, 1962). onion), and Local variety2 (long-type onion), were used Monthly mean air temperature, soil temperature at a in the experiments. The first four cultivars were produced depth of 20 cm, and total rainfall data are shown in Figure from seed, and the last two were produced from vegetative 1 (data from the Turkish State Meteorological Service). production material. All cultivars were planted 6 cm Monthly mean temperatures of the air and the soil at a apart. Two sets of each cultivar were planted collaterally depth of 20 cm changed from ‒1.8 to 25.2 °C and from in nematicide-treated and untreated control blocks 2.5 to 27.8 °C, respectively, in 2012–2013. Extremely low with seven replications using a completely randomized temperatures were recorded during November‒March block design. Nematicide containing 400 g/L of active and these increased after March until July, then decreased fenamiphos was applied to seed pads in the rows at planting gradually during the 2 years. Most precipitation was at a dosage of 5.04 kg/ha (Roberts and Greathead, 1986; observed in January (45.4 mm), November (44.0 mm), Gray and Soh, 1989; Andres and Lopez-Fando, 1996). The and December (52.8 mm) in 2012, whereas in 2013 most two experiments were set up on 24 and 25 March 2012 and precipitation was observed from the beginning of the year 2013 and harvested on 9 and 21 September 2012 and 2013 until May (15.2‒71.4 mm). during the two onion growing seasons. The soil texture of the field was sand, silt, and clay 2.3. Soil sampling and nematode analysis (20.68%, 34.87%, and 44.44%, respectively), and the field The experimental plots were sampled three times each soil was classified as clay soil type. Soil pH was weak year: after establishment of experimental plots, 1 day

80 Monthly total prec p tat on (mm) 70 Monthly mean a r temperature (°C) 60 Monthly mean 20- cm depth so l temperature (°C)

50

40

30

20

10

0

–10 July July May May June June Apr l Apr l March March August August January January October October February February December December November November September September

2012 2013

Months Figure 1. Monthly mean air and 20-cm soil depth temperatures and monthly total rainfall in Karaman Province during 2012 and 2013 (data from Turkish State Metrological Service).

228 YAVUZASLANOĞLU et al. / Turk J Agric For before onion planting (Pi1: initial population 1); 2 weeks plots and nematicide-treated plots, respectively, for the later, after planting and nematicide application (Pi2: initial 2 years. The second initial population levels of D. dipsaci population 2) to see the effect of nematicide on nematode decreased significantly in the nematicide-treated plots (42 populations; and at the end of the experiment preharvest individuals/100 g of dry soil), but were detected at high (Pf: final population). Plants were not available at initial density in the untreated control plots (132 individuals/100 population sampling times, so therefore soil nematode g of dry soil) as an average for the 2 years. populations were evaluated at all sampling times for The initial nematode populations (Pi1 and Pi2 comparison. together) in both the nematicide-treated and untreated Soil samples (1 kg) were collected from 15 points control plots were significantly higher during the first year representative of the plot from a 20-cm soil depth using (104 individuals/100 g of dry soil) than during the second a soil corer 2.5 cm in diameter. Nematodes were extracted year (68 individuals/100 g of dry soil) (P < 0.05). from 100 g of soil taken from each sample by using the A significant, positive polynomial regression was modified Baermann funnel technique (Hooper, 1986). observed between the initial and final nematode Ditylenchus dipsaci populations were counted in a 50- populations of the Betapanko, Pan88, and Local variety1 µL subsample taken from 1 mL of nematode suspension cultivars, whereas a negative polynomial regression was under a light microscope at 20× magnification. observed for the Valenciana cultivar in the first year (P < Nematode populations were presented as number of 0.05; Figure 2). A significant relationship was determined individual nematodes per 100 g of dry soil. Multiplication between Pi1 and Pf for the Valenciana and Local variety1 rates of nematodes were calculated by dividing the cultivars and between Pi2 and Pf for the Betapanko and nematode numbers/100 g of dry soil in the final population Pan88 cultivars. No relationship was detected in any of the into nematode numbers/100 g of dry soil in the initial cultivars for the initial and final nematode populations in population (Pi1/Pi2). the second year of the experiment. Only Local variety1 2.4. Plant parameters had a significant positive relationship between Pi1 and Ten onions randomly harvested from each plot were Pf when data for the 2 years were evaluated together (P < weighed after drying at room temperature in the 0.05; R = 0.37). laboratory. Diameter and length of the 10 sampled onions The initial population (Pi2)/100 g of dry soil and were recorded (Abd El-Al et al., 2010; Ibrahim, 2010). reproduction rate of D. dipsaci in all plots during the 2 years Yield (t/ha) of each plot was determined, and the increase of the experiment were significantly negatively related. The in yield was calculated considering the yield difference reproduction rate decreased when initial population levels between nematicide-treated and untreated control plots of increased (P < 0.05; Figure 3). each replication. 3.2. Plant parameters 2.5. Statistical analysis Yield parameters for the onion cultivars were significantly Nematode numbers from Pi1 and Pi2 were compared by higher during the second year than during the first year of applying analysis of variance (ANOVA) and Student’s t-test the experiment. Yield in the first year was 8.3 t/ha, whereas in nematicide-treated and untreated control plots for both during the second year it was 16.2 t/ha (P < 0.05) for all years. Initial and final (Pi1 and Pi2) nematode populations treatments and cultivars. of each cultivar in each year separately and both study years The yield parameters for the nematicide-treated and together were compared using multivariate correlation untreated control plots and the yield increase (%) of analysis. ANOVA and Student’s t-test were performed to the onion cultivars are shown in Tables 1 and 2 for both distinguish differences between the yield parameters of growing seasons. There was no bulb yield difference for cultivars. the Betapanko cultivar in the first year, and yield in the Yield (t/ha) and mean diameter and length of onion nematicide-treated plots decreased in Local variety1 and cultivar data were subjected to multivariate correlation Local variety2 in the second year at rates of 10.52% and analysis depending on the Pi1 and Pi2 of D. dipsaci for 10.50%, respectively. In addition, the yields of other onion each year separately and both study years together. cultivars increased in nematicide-treated plots. Bulb yield of the Pan88 cultivar was significantly negatively correlated 3. Results with the initial D. dipsaci population (Pi1) in untreated plots during the first year. While initial population 3.1. Nematode populations density increased, onion bulb yield decreased at a rate Initial population densities were significantly different of 2.08% during the first year (Figure 4). Additionally, a after nematicide application (P < 0.05). The first initial slight negative relationship was detected between bulb population levels (Pi1) of D. dipsaci averaged 87 and 82 diameter (R = 0.57) and bulb length (R = 0.59) in the individuals/100 g of dry soil in the untreated control initial population (Pi1) of D. dipsaci in the Pan88 cultivar.

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100 90 70 80 60 a b 70 2 50 y = –0.000 x + 0.297x –1.900 60 R² = 0.279 40 50 y = 0.001 x2 –0.528 x + 45 .46 30 40 30 R² = 0.265 20 20 10 10 0 F nal populat on (/100 g dry so l) 0

F nal populat on (/100 g dry so l) 050 100 150 200 250 300 –10 050 100 150 200 250 In t al populat on (P 2) (/100 g dry so l) In t al populat on (P 1) (/100 g dry so l)

100 50 90 c 45 d 80 40 70 y = –0.000 x2 + 0.173 x–2.591 y = 0.003 x2 –0.434 x + 8.668 35 60 R² = 0.541 R² = 0.620 30 50 25 40 20 30 15 20 10 10 5 F nal populat on (/100 g dry so l) F nal populat on (/100 g dry so l) 0 0 050 100 150 200 250 0 100 200 300 400 In t al populat on (P 2 ) (/100 g dry so l) In t al populat on (P 1) (/100 g dry so l) Figure 2. Significant relationship between initial and final populations of Ditylenchus dipsaci on onion cultivars in the 2012 growing season. a) Betapanko cultivar, b) Valenciana cultivar, c) Pan88 cultivar, d) Local variety1 cultivar.

20 12 18 10

e 16

rat 14 8 12 6 y = –0.057 x + 8 .817 10 R² = 0.673 8 4

Reproduct on 6 y = –0.002 x + 0.567 Bulb y eld (tone / ha ) 4 R² = 0.013 2 2 0 0 0100 200 300 400 500 050 100 150 200 In t al populat on (P 2)/100 g dry so l In t al populat on (P 1)/100 g dry so l Figure 3. Relationship between initial population (Pi2) and Figure 4. Relationship between bulb yield and initial Ditylenchus reproduction rate of Ditylenchus dipsaci in all plots in the 2 years dipsaci population (Pi1) in the Pan88 cultivar in the 2012 growing of the experiment. season.

Similarly, the Betapanko cultivar had a significant negative 4. Discussion relationship between initial nematode population and The effects of D. dipsaci on the yield of commercial onion bulb yield for both study years together (Figure 5). No cultivars were evaluated using nematicide treatment under yield loss was recorded in the first year, but a 12.93% yield Karaman agroecological field conditions. loss occurred in the second year. The nematicide fenamiphos was used effectively to Only the Local variety1 cultivar had a slight reduce the D. dipsaci populations, and the most effective significant positive relationship between initial nematode time for application was at planting (Roberts and population (Pi1) and bulb yield in the second year. Yield Greathead, 1986; Andres and Lopez-Fando, 1996). The of Local variety1 increased linearly according to the initial significant reduction (48%) in D. dipsaci populations population of D. dipsaci (Figure 6). after fenamiphos application in both growing seasons in

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Table 1. Yield parameters of the different onion cultivars in nematicide-treated and untreated control plots in the 2012 growing season.

Bulb diameter (cm) Bulb length (cm) Bulb yield (t/ha) Yield increase Onion cultivar Tr.* Untr.* Tr. Untr. Tr. Untr. (%)

Kantaropu 3.26 3.54 4.90 4.53 5.2 4.0 30.00

Betapanko 3.11 2.94 4.70 5.12 3.1 3.1 0.00

Valenciana 3.59 3.59 4.69 4.65 7.5 5.3 41.50

Pan88 3.63 3.58 4.50 4.49 04.9 4.8 2.08

Local variety1 4.68 4.55 4.11 4.00 14.1 13.1 7.63

Local variety2 3.20 3.21 7.96 7.58 12.9 12.2 5.73

Tr*, nematicide-treated; Untr*, untreated control plots.

Table 2. Yield parameters of different onion cultivars in nematicide-treated and untreated control plots in the 2013 growing season.

Bulb diameter Bulb length Bulb yield (ton/ha) Yield increase Onion cultivar Tr.* Untr.* Tr. Untr. Tr. Untr. (%)

Kantaropu 4.83 5.22 6.12 5.91 15.3 14.1 8.51

Betapanko 4.33 4.69 7.26 6.22 13.1 11.6 12.93

Valenciana 4.50 4.92 6.78 6.43 18.6 15.6 19.23

Pan88 5.00 4.13 6.29 7.63 17.3 15.0 15.33

Local variety1 4.83 4.93 6.34 6.71 17.0 19.0 –10.52

Local variety2 4.28 4.50 6.87 6.86 17.9 20.0 –10.50

Tr*, nematicide-treated; Untr*, untreated control plots.

35 25 30 20 25 y = 0.027 x + 16 .69 R² = 0.112 15 20 y = –0.028 x + 9.576 15 10 R² = 0.154 10 Bulb y eld (t/ha)

Bulb yeld (t/ha) 5 5 0 0 0 100 200 300 400 050 100 150 200 250 300 Intal populaton (P1)/100 g dry sol In t al populat on (P 1)/100 g dry so l Figure 5. Relationship between bulb yield and initial Ditylenchus Figure 6. Relationship between bulb yield and initial Ditylenchus dipsaci population (Pi1) in the Betapanko cultivar for both study dipsaci population (Pi1) in the Local variety1 cultivar in the 2013 years. growing season.

231 YAVUZASLANOĞLU et al. / Turk J Agric For this study supported the previous observations regarding increase was not related to the initial nematode population effectiveness of the nematicide fenamiphos. in this study. Initial nematode population densities in the The Local variety1 yield decrease of 10.52% following experiments had a significant relationship with yield nematicide application in the second year was supported reductions. The damage observed could be economically by a regression analysis showing a tolerant reaction to D. important considering the findings of Seinhorst (1956), dipsaci. However, a yield increase was observed during who found that 0.2‒1 fourth-stage D. dipsaci larvae/100 g the first year following nematicide application. The of soil was related to economic damage in onion. Similarly, higher initial population level during the first year may Palo (1962) reported that 10 D. dipsaci/500 g of soil be responsible for this result; Seinhorst (1965) reported induced damage and Mennan (2005) recorded damage that damage caused by root-feeding nematodes was with 5 D. dipsaci/onion plant. proportional to their population density. Significant positive relationships of the initial and The Local variety2 and Kantaropu cultivars were not final D. dipsaci nematode populations in the Betapanko, significantly correlated with any of the yield parameters Pan88, and Local variety1 cultivars were observed in 2012, investigated. However, yield increases with nematicide which points to susceptibility of the onion cultivars. In application were comparable with the findings of contrast, there was a negative relationship in the initial Tunçdemir (1988), Sturhan and Brzeski (1991), and and final D. dipsaci populations in the Valenciana cultivar Mennan (2001). in the first year. Seinhorst (1967) suggested that the The study showed that D. dipsaci has a significant negative relationship between the initial populations and effect on yield performance of commercially grown onion the reproduction rate of D. dipsaci was a complex effect cultivars under Karaman agroecological conditions. of nematode competition for food and space, hosting Preliminary responses of certificated and commercially ability of the plant, and environmental conditions. The grown onion cultivars to D. dipsaci were recorded in field reproduction rates were mostly less than 1, presumably conditions in Turkey. because of the downward movement of the nematodes at The next phase of the study is to extend the the end of the growing season in September, as reported by investigation to genetic reactions in other onion cultivars Dikici and Yavuzaslanoglu (2013). grown commercially in Turkey. Cook and Evans (1987) defined tolerance as the ability of a cultivar to maintain yield potential in the presence of Acknowledgments nematodes. According to this definition, the Betapanko The authors thank the Scientific and Technological and Pan88 cultivars were intolerant. Yield in untreated Research Council of Turkey (TÜBİTAK 3501, Project plots decreased depending on the nematode population No.: 111O222) for financial support and Dr. Uğur Gözel increase. (Department of Plant Protection, Faculty of Agriculture, The highest yield increase recorded following Çanakkale Onsekiz Mart University) for reading the application of nematicide was in the Valenciana cultivar manuscript and for his valuable contributions. during both years of the experiment; however, the yield

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