Note: Pyrethroid resistance and possible involvement of glutathione<Emphasis Type="Italic">S</Emphasis>-transferases in<Emphasis Type="Italic">Helicoverpa armigera</Emphasis> from Turkey

An introductory study was conducted to investigate the pyrethroid resistance ofHelicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) strains in Turkey, collected from cotton fields in the Adana and Antalya provinces, through two different synthetic pyrethroid insecticides: lambda-cyhalothrin and esfenvalerate. In addition, the roles of glutathioneS-transferases (GSTs) in this resistance mechanism were analyzed. It was found that whereas resistance ratios for lambda-cyhalothrin (LD₅₀ levels) were 3- and 98-fold increased in the Adana and Antalya strains, respectively, esfenvalerate ratios were 3.3- and 92.3-fold increased in the Adana and Antalya strains, respectively, with respect to the susceptible strain. Furthermore, Adana and Antalya strains showed 2.4- and 2.9-fold higher GST activities than the susceptible strain, respectively. In the Antalya field strain, the minor increase in GST activity compared with the resistance levels implies that GSTs may be not greatly involved in this resistance. It also provides evidence that they could not be the only metabolic mechanism responsible for resistance to lambda-cyhalothrin and esfenvalerate inH. armigera from Turkey. http://www.phytoparasitica.org posting Nov. 16, 2006.     

Effects of tillage on productivity of a winter wheat-vetch rotation under dryland Mediterranean conditions

An experiment was conducted to determine the effects of three tillage systems on crop yield in a winter wheat-vetch (Vicia sativa L.) rotation during 3-year growing seasons on a clay-loam soil in the northwest region of Turkey. The three tillage treatments were: (1) conventional tillage (CT); (2) shallow tillage (ST); (3) double disk tillage (DD).The wheat grain yield was significantly affected by tillage when averaged across years. The highest wheat grain yield was obtained with shallow tillage treatment. The year affected wheat grain yield significantly, mainly due to the distribution of rainfall through the growing season and probably due to the wheat-vetch rotation. Heads density and head length increased significantly with shallow tillage when compared with conventional tillage. Tillage practices had no significant influence on thousand kernel weight. Results from this study indicated that for a dryland wheat-vetch rotation cropping system, shallow tillage had higher wheat grain yields than that obtained from conventional tillage. Furthermore, mouldboard ploughing tillage in this crop rotation could be replaced by shallow tillage that would increase yield and would be likely to improve soil properties in the long-term. On the other hand, double disk tillage proved to be a promising soil management practice to improve vetch grain yield when compared with conventional tillage.     

Effect of different tillage systems on the quality and crop productivity of a clay–loam soil in semi-arid north-western Turkey

A 2-year study was conducted to investigate the effect of three tillage systems on the properties of clay–loam soil (EutricVertisol) planted with winter wheat (Triticum aestivum L.) in the Canakkale province of north-western Turkey. Crop productivity was also evaluated. The three tillage treatments were: (1) conventional tillage involving mouldboard ploughing followed by two discings (MT); (2) shallow tillage consisting of rototilling followed by one discing (RT); (3) double discing (DD). In the first year of the study, bulk density (BD) was found significantly lower under RT at both 0–10 and 10–20 cm depths with 1.24 and 1.32 Mg cm⁻³, respectively, when compared to MT treatment. However, MT at 20–30 cm provided the highest BD, at 1.49 Mg cm⁻³. In the second year of the study, DD had the lowest BD at all depths followed by RT and MT. Based on the 2-year mean, aggregate size distribution (ASD) and mean weight diameter (MWD) were significantly influenced by tillage treatments. The greatest MWD was obtained with DD, followed by MT and RT. Increasing MWD and coarse aggregates decreased seedling emergence. Organic carbon increased after RT, DD, and MT by 58%, 30%, and 18%, respectively, when compared to the amount at the beginning of the study. Similarly, the total N in the soil and straw was higher after RT than the other treatments. At 1.76 MPa, penetration resistance at 18–30 cm was significantly higher during the growing period using DD, followed by RT with 1.35 MPa and MT with 1.33 MPa. There was no significant difference between treatments at 0–18 cm. Increasing OC and total N and decreasing BD and PR under RT increased grain yield to 4611 kg ha⁻¹, followed by MT and DD at 4375 and 4163 kg ha⁻¹, respectively, according to the 2-year mean.     

Use of L-carnitine and humate in laying quail diets

This experiment was carried out to determine the effects of using L-carnitine and humate alone or in combination in quail diets on laying performance, egg traits and blood parameters. A total of 280 Japanese quails aged 10 weeks, divided into one control group and three treatment groups, were used. The diets of the first, second and third treatment groups were supplemented with 100 mg L-carnitine/kg, 1.5 g humate (Farmagülat?r Dry Plus)/kg and 100 mg L-camitine + 1.5 g humate/kg, respectively. The experimental period lasted 16 weeks. The addition of L-carnitine and sodium humate alone or in combination did not significantly affect body weight, feed consumption, egg production, feed conversion ratio, mortality, egg-shell thickness, egg yolk index and the percentages of egg-shell, albumen and yolk. Egg weight increased (P < 0.001) with L-carnitine supplementation. The values of egg albumen height (P < 0.05), egg albumen index (P < 0.01) and egg Haugh unit (P < 0.05) were increased with humate supplementation. Egg cholesterol content and blood serum parameters were not affected by the supplementation of L-carnitine with or without humate. The results in this study demonstrated that L-carnitine supplementation increased egg weight while humate addition increased egg albumen index and egg Haugh unit of laying quails. However, the combined administration of L-carnitine and humate did not have any significant effects on the parameters measured.     

Nutrient concentration and yield of maize (Zea mays L.) after vetch (Vicia sativa L.) in conventional and reduced tillage systems

The effects of tillage on plant availability nutrients are critical to develop nutrient management strategies to optimize yield. The objective of this study was to evaluate differences in the concentration of 19-nutrient and yield after 4-year of conventional [moldboard plough (MT)] and two reduced [rototiller (ST) and chisel (CT)] tillage systems in maize (Zea mays L.) after winter vetch (Vicia sativa L.) in double crop one year. Three tillage systems were compared from 2005 to 2008 in area located in the western region of Turkey under semi-arid Mediterranean clay-loam soils. Nutrients were determined in maize leaves, stems, roots and soils. Results show that the concentration of macronutrients were found to be higher in leaves and stems of maize than roots in three tillage systems of all years, while the opposite was true for micronutrients. Among the macro and micro-nutrients, there was no effect of tillage on nutrient concentration in all maize tissues for sulfur, magnesium, sodium and copper (S, Mg, Na and Cu). However, the nitrogen, potassium, calcium, boron, zinc, manganese, iron, aluminum, barium, cadmium, cobalt, chromium, nickel, lead and selenium (N, K, Ca, B, Zn, Mn, Fe, Al, Ba, Cd, Co, Cr, Ni, Pb and Se) were affected by tillage. ST increased N in stems of 2006 compared with other systems. K in roots of 2006 was 52 and 30% greater in CT than in ST and MT, respectively, while ST and MT of 2007 resulted in 38 and 41% greater than CT. In two of four years, ST contributed to higher grain yield compared with other systems. In general, ST can effectively contribute to increase maize yield following winter vetch compared with MT under this region. Results suggested the need for different management systems associated with reduced tillage including rotation, particularly for basic nutrients. Further, results showed similarities and differences with other studies under tillage with maize following winter vetch.     

Tillage effects on soil properties and maize productivity in western Turkey

Information regarding the evaluation of long-term tillage effects on soil properties and summer maize growth after winter vetch in western Turkey is not available. Therefore, this study was conducted for 5 years with three types of tillage including conventional (mouldboard plough) and conservation (rototiller and chisel). Results indicated that tillage had no significant effect on penetration resistance, except at the bottom of 20 cm soil depth where it was higher in mouldboard plough than in rototiller and chisel. Bulk density in the topsoil of 10 cm decreased with the degree of soil manipulation during tillage practices. Rototiller caused significantly higher root, leaf and stems biomass and plant height than the other systems. The root dry weight was higher in the topsoil of 10 cm than at the bottom of this soil depth for all systems. The highest root dry weight was found in fourth year of chisel, but the lowest was recorded in the same year of plough, especially at the bottom of 20 cm due to higher penetration. Rototiller improved soil properties and maize growth compared to other systems in 2 of 5 years. We concluded that using rototiller for maize after winter vetch will be more effective compared with other systems.     

Note: Insecticide resistance in<Emphasis Type="Italic">Helicoverpa armigera</Emphasis> from cotton-growing areas in Turkey

Insecticide resistance inHelicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is one of the most important constraints on cotton production in Turkey. We investigated the susceptibility ofH. armigera strains collected from cotton fields in the Adana, Hatay and Antalya provinces to insecticides which are in wide use. LD₅₀ values for tralomethrin, lambda-cyhalothrin, endosulfan, profenofos and methomyl were determined by topical bioassay. At the LD₅₀ levels, resistance ratios for tralomethrin were 24.7-, 19.7- and 15.7-fold in the Adana, Hatay, and Antalya strains, respectively; and for lambda-cyhalothrin were 41-, 20-and 40-fold, respectively. Resistance ratios ranged from 1.2- to 2.1-fold in all field strains for endosulfan, profenofos and methomyl, with no significant resistance. These results suggest the presence of resistance to tralomethrin and lambda-cyhalothrin inH. armigera strains collected from cotton fields, but no resistance to endosulfan, profenofos or methomyl could be observed.     

Effects of dietary dried baker’s yeast on the performance,egg traits and blood parameters in laying quails

This study was conducted to investigate the effects of dietary dried baker’s yeast on laying performance, egg traits and some blood parameters of quails. In the experiment a total of 342 Japanese quails (Coturnix coturnix japonica) aged ten weeks were equally divided into six groups of 57 (three replicates of 19 quails each). Six levels (0, 4, 8, 12, 16 and 20%) of dried baker’s yeast were included in isonitrogenous and isocaloric diets. The experimental period lasted 14 weeks. At the end of the experiment, there were no significant differences among the groups in body weight, feed intake, protein intake, egg production, feed efficiency, egg yolk index and egg haugh unit. Blood serum levels of total protein, triglyceride and cholesterol were not affected by dietary dried baker’s yeast. Diets containing 4 and 8% of dried baker’s yeast increased the egg weight significantly (p < 0.01). The inclusion of dried baker’s yeast at the level of 20% to the diets reduced egg shell thickness and egg albumen height. It is concluded that dried baker’s yeast can be used up to 16% in the diets of laying quails without adverse effects on the measured parameters.