EVALUATION OF WHEAT YIELD LOSSES CAUSED BY ROOT LESION NEMATODES IN HAMADAN PROVINCE, IRAN

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1 EVALUATION OF WHEAT YIELD LOSSES CAUSED BY ROOT LESION NEMATODES IN HAMADAN PROVINCE, IRAN MAZDOSHT GITTI 1, *, SEYED ABBAS HOSEININEJAD 2, AND ABDELFATTAH A. DABABAT 3 1 Plant Protection Research Department, Hamadan Agricultural and Natural Resources Research Center, AREEO, Hamadan, Iran. 2 Iranian Research Institute of Plant Protection, Agricultural Research Education and Extension Organization (AREEO), Tehran, Iran, 3 ICARDA-CIMMYT Wheat Improvement Program, P.K. 39 Emek, 06511, Ankara, Turkey. *Correspondence author Mazdyashtg@gmail.com SUMMARY Pratylenchus thornei and P. neglectus are the most common root lesion nematodes (RLN) on wheat with economically important damaging capabilities. On the basis of previous studies both species are prevalent in the province and are damaging crops especially in rainfed wheat fields. In order to evaluate yield losses caused by root lesion nematodes on wheat in Hamadan, a two-year field trial with four split-plot replications on a randomized completed block design were conducted in a naturally infested field during Two wheat cultivars (Sardari and Azar), two barley cultivars (Makuii and Abidar), and a triticale cultivar (Juanillo92) were sown in 2 5 m plots in 10 lines. Five lines of each plot were treated with aldicarb 10G, 0.8 g a.i..s/m 2 soil at sowing time. Soil samples were taken from each plot by auger one month after sowing and one month before harvest, and root lesion nematodes were extracted and counted. For both years the grain yield was recorded for each plot. Analysis of data with SAS statistical program showed there was a significant difference between means and nematicidal application which caused 84% and 92% de- * Gitti M, Hoseininejad SA, Dababat AA (2015) Evaluation of wheat yield losses caused by root lesion nematodes in Hamadan Province, Iran. In Nematodes of Small Grain Cereals: current status and research. (AA Dababat, H Muminjanov and RW Smiley) pp (FAO: Ankara, Turkey). 101

2 Gitti, Hoseininejad and Dababat crease in RLN populations and 6.7% and 22.3% increase of grain of wheat in the first and second year, respectively. There was a significant linear relationship between RLN density and wheat grain yield of Sardari and Azar cultivars with the estimated regression equation; Y= x x and R 2 = , where Y is the grain yield in gr/m 2 and x is the number of RLN per gram oven-dried soil. Sardari wheat cultivar was more susceptible than Azar cultivar whereas barley and triticale revealed less difference in grain yields with different root lesion nematode densities. INTRODUCTION Wheat (Triticum aestivum L.) as a main crop is planted each year on ha as rainfed with 1103 kg/ha yield in the low-precipitation region (150 to 300 mm) and ha with 3800 kg production per ha in irrigated fields in Hamadan Province. In most areas winter wheat is rotated with a 14-month fallow (crop-free) period and in some areas winter wheat without fallow (Anon 2014). However, wheat or barley (Hordeum vulgare L.) are sown in rainfed fields annually while irrigated fields have rotations that include broadleaf crops such potato, alfalfa, sugarbeet, chickpea or canola. Root-lesion nematodes (Pratylenchus neglectus (Rensch, 1924) Filipjev Schuurmanns & Stekhoven, 1941 and P. thornei Sher & Allen 1953) are present in 82% of the fields in the province and effects of crop management practices on nematode populations have not been clearly defined (Tanha Maafi et al. 2009). Direct associations between Pratylenchus spp. population density and frequency of cereal cropping have been reported in other countries (Gair et al. 1969, Riley et al. 2002). A replicated 2-year experiment was established during to examine the aspects of RLN damage on wheat at a low precipitation site known to be infested with P. neglects and P. thornei. METHODS The experiment was performed at the Ekbatan Agricultural Research Station (EARS) located 5 km northwest of Hamadan. A uniform crop of winter wheat was planted over the intended experimental area during 2012 in order to maintain the RLN population. The experimental area was divided into 24 plots of 2 5 m arranged as four randomized blocks of six plots representing six treatments. Plots had 10 lines, and five lines of each plot were treated with aldicarb 10G, 0.8 g a.i..s/m 2 soil at sowing time. The six treatments included biennial 102

3 Figure 1. The experimental site of evaluation of wheat and barley yield losses caused by root lesion nematodes in Hamadan Province, Iran, 2014 Sardari and Azar winter wheat, biennial Makuii and Abidar winter barley, and triticale cultivar Juanillo92. All crops were harvested in mid September. Grain yield was measured using a weigh wagon to determine yield per plot. Routine soil sampling for nematode extraction was collected each year to assess Pratylenchus populations in individual treatments when soil was moist. Soil samples were taken from each plot by an auger (2.5-cm diameter) one month after sowing and one month before harvest. Samples consisted of 20 cores composited for each of 24 plots. All soil-dwelling nematodes from 250-g subsamples of soil plus root fragments were extracted by the Whitehead tray method (Whitehead and Hemming 1965). Nematodes were washed into 100-ml cups and suspensions were stored at 5 C before counting. One ml of suspension was placed on a counting slide, and all plant-parasitic nematode genera on the slide were counted, identified, and recorded as nematodes/kg of oven-dried soil. Results were analyzed using one-way analysis of variance (ANOVA). Each analysis was performed using SAS Statistical Software. Associations of grain yields and nematode populations were evaluated by regression analysis. RESULTS Numbers of isolated RLN were greater than any other plant-parasitic species, which were detected infrequently and in low numbers. Pratylenchus populations did not significantly differ (P < 0.05) among treatments during the 2 years of the experiment. Aldicarb reduced (P <0.01) Pratylenchus densities in soil and roots for two years in treated plots (Table 1). Applying aldicarb caused a 84% and 92% decrease in RLN populations and 6.7% and 22.3% increase in grain of wheat during the first and second year, respectively. The yield aldi- 103

4 Gitti, Hoseininejad and Dababat carb interaction was significant and when data for control plots (not treated with aldicarb) were analyzed separately, the varietal difference was significant at P < Grain yields also were improved by aldicarb in each experiment (P < 0.01). There was a significant negative linear relationship between RLN density and wheat grain yield of Sardari and Azar cultivars with the estimated regression equation; Y= x x and R 2 = , where Y is the grain yield in gr/m 2 and x is the number of RLN per gram oven-dried soil. Table 1. Density of Pratylenchus in one gram of soil in aldicarb-treated and untreated plants at Ekbatan Agricultural Research Station during 2013 and 2014 Cereals Year Sardari (wheat) Azar (wheat) Abidar (barley) Makuii (barley) Triticale Aldicarb Check Aldicarb Check Aldicarb Check Aldicarb Check Aldicarb Check Table 2. Grain yields of aldicarb-treated and untreated plants at Ekbatan Agricultural Research Station during 2013 and 2014 Cereals Year Sardari (wheat) Azar (wheat) Abidar (barley) Makuii (barley) Triticale Aldicarb Check Aldicarb Check Aldicarb Check Aldicarb Check Aldicarb Check DISCUSSION We report the first field-derived evidence that Pratylenchus spp. causes economic damage to wheat in the west regions of Iran. In soils with high populations of Pratylenchus spp., aldicarb application improved yield and grain weight. Observations of yield differences due to varietal tolerance and resistance to Pratylenchus spp. in the west of Iran are important because they indicate a potential for improving yields of locally-adapted varieties by incorporating parental lines with improved tolerance and resistance to Pratylenchus spp. into the breeding programs. However, Sardari and Azar are well adapted to production systems in the west of Iran. Compared to non-treated controls, aldicarb treatments yields were higher by an average of 14.5%. Invasion of roots by Pratylenchus spp. generally does not 104

5 Figure 2. Relationship between numbers of Pratylenchus spp. and yield of Sardari and Azar winter wheat during two years at the Ekbatan Agricultural Research Station cause diagnostic symptoms to occur in the foliar canopy. Plants with heavily damaged roots may exhibit stunting, poor vigor, reduced tillering, and premature wilt at the onset of moisture stress (Doyle et al. 1987, Orion et al. 1984, Van Gundy et al. 1974). Although crop rotation is a preferred management practice, limiting damage by Pratylenchus spp. through rotation is a continuing challenge because RLN species infest a wide range of host plant species (Hollaway et al. 2000, Talavera and Vanstone 2001, Thompson et al. 1999, Vanstone and Russ 2001a 2001b). In general, most commercial wheat and chickpea varieties are considered good hosts for P. thornei. Poor hosts include many varieties of barley, durum wheat, canola, safflower, lupine, lentil, field pea, and flax. Of the listed crops, only barley is adapted to the Hamadan small grain-production region, where precipitation has a winter-dominant pattern and temperatures are very low, and summers are hot and dry. Assessment of barley as a potential break crop is required. Likewise, much progress and promise exists for breeding wheat varieties with sufficiently high tolerance and (or) resistance to stabilize yields and reduce the reproductive efficiency for Pratylenchus.spp. Development of tolerant, locally-adapted varieties is essential for limiting damage by Pratylenchus spp. Pratylenchus spp. population densities were strongly influenced by cropping systems in the low-precipitation region. These results are in agreement with previous observations (Gair et al. 1969, Riley et al. 2002). Although 105

6 Gitti, Hoseininejad and Dababat populations of Pratylenchus spp. were not monitored in the volunteer cereals and weed grasses in this experiment, there was ample opportunity for multiplication of nematodes through the 10-month winter wheat growth cycle and also, when temperatures permitted, for as many as seven months of cycle. We conclude that management of Pratylenchus spp. populations in the winter wheat region of western Iran must include elimination of the bridging and multiplication potential by unwanted hosts during the fallow period, as has been shown to be essential for reducing risks posed by other pests and diseases of wheat roots and foliage. ACKNOWLEDGMENTS We would like to thank Dr. Zahra Tanha Maafi, Iranian Research Institute of Plant Protection, Tehran, Iran for her contribution and support. REFERENCES Anon (2014) Agricultural Statistical Yearbook. Tehran, Iran, Ministry of Jihad-E- Agriculture, Statistical and Information Technology Unit, 271 pp. Doyle AD, McLeod RW, Wong PTW, Hetherington SE, Southwell RJ (1987) Evidence for the involvement of the root lesion nematode Pratylenchus thornei in wheat yield decline in northern New South Wales. Australian Journal of Experimental Agriculture, 27, Gair R, Mathias PL, Harvey PN (1969) Studies of cereal nematode populations and cereal yields under continuous or intensive culture [Heterodera avenae, Pratylenchus neglectus, Trichodorus primitivus]. Annals of Applied Biology, 63, Hollaway GJ, Taylor SP. Eastwood RF, Hunt CH (2000) Effect of field crops on density of Pratylenchus in southeastern Australia. Part 2: P. thornei. Journal of Nematology, 32, Orion DJA, Kirkun J (1984) Field observations on Pratylenchus thornei and its effects on wheat under arid conditions. Revue de Ne matologie, 7, Riley IT, Kelly SJ (2002) Endoparasitic nematodes in cropping soils of Western Australia. Australian Journal of Experimental Agriculture, 42, Smiley RW (2009) Root-lesion nematodes reduce yield of intolerant wheat and barley. Agronomy Journal, 101, Talavera M, Vanstone VA (2001) Monitoring Pratylenchus thornei densities in soil and roots under resistant (Triticum turgidum durum) and susceptible (Triticum aestivum) wheat cultivars. Phytoparasitica, 29,

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