Influence of Pollination on Smut Disease and Yield in Maize
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Tarım Bilimleri Dergisi Journal of Agricultural Sciences Tar. Bil. Der. Dergi web sayfası: Journal homepage: www.agri.ankara.edu.tr/dergi www.agri.ankara.edu.tr/journal Influence of Pollination on Smut Disease and Yield in Maize Mehmet AYDOĞDUa, Nuh BOYRAZb aBatı Akdeniz Agricultural Research Institute, Department of Plant Health, Antalya, TURKEY bSelçuk University, Faculty of Agriculture, Department of Plant Protection, Konya, TURKEY ARTICLE INFO Research Article DOI: 10.15832/ankutbd.490958 24 (2018) 463-470 Corresponding Author: Mehmet AYDOĞDU, E-mail: [email protected], Tel: +90 (533) 726 89 85 Received: 09 March 2017, Received in Revised Form: 05 September 2017, Accepted: 01 November 2017 ABSTRACT Ustilago maydis, causal agent of smut disease in maize, induces significant yield losses by forming colossal galls (tumours) on cobs. Since infection process of U. maydis is parallel with natural pollination of maize, an interaction between maize pollination and the smut fungus is probable. To reveal this interaction perceptibly, a 2-year field study was carried out in Antalya province of Turkey. As host plants, 8-maize-cultivars belonging to different maize variety groups [dent (Ada-523, Pioneer-3394 and Side), flint (Karaçay and Karadeniz Yıldızı), sweet (Merit and Vega) and popcorn (Antcin-98)] were used in the experiment. Inoculations were performed by injecting inoculum into cob silks in pre- and post-pollination periods in plots. In addition, control plots were set up for each treatment. In conclusion, average disease severity, incidence and yield losses of all the maize cultivars in pre-pollination inoculations (PrePI) were 3.8, 20.7 and 45.5%, whereas in post-pollination (PostPI) inoculations, they were 0.9, 15.7 and 35.9%, respectively. It was found that in both years, disease values of the PrePI were higher than those of the PostPI. This study suggested that pollination period of maize is an important factor affectingU . maydis infection in cobs and accordingly yield losses. Keywords: Maize pollination; Ustilago maydis; Yield loss © Ankara Üniversitesi Ziraat Fakültesi JOURNAL OF AGRICULTURAL SCIENCES JOURNAL OF AGRICULTURAL When maize seedlings are infected by the fungus, 1. Introduction — Maize is a staple crop for human and animal small galls appear on the leaves and stems, and the nutrition as well as fodder industry (Kırtok 1998). In seedling may remain stunted or may be killed. On 2013, total maize production in the world exceeded older plants, infections occur on the young, actively one billion tons (FAO 2015). However, Ustilago growing tissues of axillary buds, individual flowers maydis (DC) Corda, called also as corn smut, is one of the cob and tassel, leaves and stalks. Infected of the primary constraint to maize yield. The disease areas are permeated by the fungus mycelium, which occurs wherever maize is grown. Unlike other cereal stimulates the host cells to divide and enlarge, thus smuts, U. maydis gives rise to local infections and forming galls. Galls are first covered with a greenish severe damages to cobs through formation of huge white membrane. Later, as the galls mature, their galls on them (Tunçdemir & Iren 1980). In addition, interior darkens and turns into a mass of powdery, TARIM BİLİMLERİ DERGİSİ TARIM it particularly causes great economic damage to dark olive-brown spores (Agrios 2005). U. maydis sweet corn (du Toit & Pataky 1999). infects stigmas in maize cobs via silks at the tip Influence of Pollination on Smut Disease and Yield in Maize, Aydoğdu & Boyraz of the cob. Sporidia of the fungus accumulate on and transmitted on PDA medium and incubated at silks (Shurtleff 1980). Infection process of stigma 25 °C. Within a week, basidiospores (sporidia) of by the fungus is as follows: when fungus sporidia the fungus appeared. Later, they were transmitted contact with stigma, sporidia mate in pairs and each to a 20% carrot solution in 500 mL flasks and pair forms a dikaryotic infection hypha and then incubated at 25 °C for one week. In this way, enter the stigma. Similarly, fertilization of stigma necessary inoculum was obtained. by pollens occurs as follows: pollens moving from tassels pass through the silk channel and 2.2. Inoculum reach to stigma and fertilize ovaries. Following With gently shaking the flasks, sporidia were moved pollination, an abscission zone consisting of layer to ensure homogeneity of the spore solution. By of dead cells in pollinated silks occurs. U. maydis means of a hemocytometer, sporidia and teliospore is not able to grow across this abscission zone suspensions were arranged to 3×106 basidiospores (Snetselaar & Mims 1993; Snetselaar et al 2001). mL-1 and 1×106 teliospores mL-1, respectively. In This phenomenon suggests that when the pollens this manner, inoculum was arranged according to reach to the ovary earlier than the infective hypha of Tunçdemir (1985). the fungus, U. maydis infection in the cobs become formidable. Correspondingly, plant may escape 2.3. Experiments from the infection. Experiments were conducted in completely The main objectives of the study were to randomized block factorial design with three perceptibly examine this phenomenon by injecting replicates. Plots, 5 m long, were set up as four rows inoculum into cob silks of different maize varieties including controls. Seeds of the each cultivar were in pre and post pollination periods and determine sown on 7 June in 2010 and on 3 June in 2011. yield losses arising from the fungus infection during Mean number of the plants in every plot were one pollination period. hundred. Furrow irrigation was used and irrigation, a total of 9 times, was done at 15 to 18 days intervals depending on the moisture in the soil. To manage 2. Material and Methods with weeds, the herbicide, foramsulfuron 22.5 g L-1 Galls on cobs were obtained from naturally infected (active substance), was used at 2 to 6 leaf stage plants in maize-producing areas of Batı Akdeniz of maize. However, deltamethrin 25 g L-1 (active Agricultural Research Institute in 2010. Flint corn substance), was applied at silking stage against varieties [Karaçay (Batı Akdeniz Agricultural earworms. Picking ears by hand from the each Research Institute) (BAARI) and Karadeniz Yıldızı plot, harvest was done. Harvest times were on 26 (Black Sea Agricultural Research Institute)], dent to 29 October in 2010, while they were on 10 to 12 corn cultivars [Ada-523 (Maize Research Institute), October in 2011. Pioneer-3394 (Pioneer Firm) and Side (BAARI)], sweet corn cultivars [Merit (May Firm) and Vega 2.4. Ecological properties of the research area (May Firm)], and popcorn variety [Antcin-98 General soil texture of the research area was clay (BAARI)] were used as host plants. loam. In sowing-time, the area was fertilized with compound fertiliser (NPK 18:8:8) at the rates of 2.1. Isolation 180 nitrogen, 80 phosphorus and 80 potassium kg Teliospores of U. maydis, also named as ha-1, respectively. Field studies were established in chlamydospores, were obtained by crumbling and Aksu location of Antalya. The total monthly rainfall filtering out the galls. Teliospores were exposed when the inoculations of the maize ears were to 1% copper sulfate solution for 20 to 60 h. performed in August of 2010 was 4.2 mm, whereas Afterwards, they were dried up using blotting paper, no measurable rainfall was recorded in the same 464 Tarım Bilimleri Dergisi – Journal of Agricultural Sciences 24 (2018) 463-470 Influence of Pollination on Smut Disease and Yield in Maize, Aydoğdu & Boyraz period in 2011. However, the average temperature Plot yield (kg ha-1)= Adjusted weight × 10000 / Plot and relative humidity in August 2010 and 2011 were area (m2) (2) 30.5 ºC, 59.1% and 29.6 ºC and 50.0%, respectively (Anonymous 2013). In conclusion, yield losses were designated by comparing yields of inoculated plots with non- 2.5. Inoculation inoculated plots. The cob inoculation method of Pataky et al (1995) 2.7. Statistical analysis was modified as follows: In total, 3 mL mixed Analysis of variance was done using JMP program inoculum, consisted of 3×106 basidiospores mL-1 (SAS Institute Inc., Cary, North Carolina, USA) and 1×106 teliospores mL-1, was syringed in primary and average values established as different were cob in pre-pollination period (3 days before natural categorized considering LSD . pollination of maize) and in the post-pollination 0.01 period (3 days after silk browning) per plant. In 2010, inoculations of PrePI and PostPI were 3. Results and Discussion performed on August 10th and 20th, while in 2011, Average disease incidence (DI) of all the cultivars those inoculations were applied on August 15th and (hosts) in PrePI was 20.7%, whereas in PostPI, that 25th, respectively. In the control plots, cobs were was 15.7%. However, the highest DI in the PrePI injected with sterile water. and PostPI were found in cv. Karadeniz Yıldızı and cv. Side, whereas the lowest DI was in cv. Antcin-98 2.6. Disease assessments (Table 1). Likewise, average disease severity (DS) Using 0 to 5 scale of Johnson & Christensen (1935), of all the hosts in the PrePI was found at the rate severity of the disease was determined. Rating of the of 3.8, while in the PostPI, it was 0.9 (Table 2). In scale was as follows: 5 = big galls (>10 cm diam); both years, average DS and DI of the hosts in the 2.5 = medium galls (5 to 10 cm diam); 1 = small PrePI were higher than that of the PostPI. In 2010, galls (2.5 to 5 cm diam); and 0 = very small galls average yields of the cultivars in the control, PrePI –1 (<2.5 cm diam). Comparing the number of infected and PostPI plots were 8180, 5240 and 5950 kg ha , respectively.