Reduction of Yield Formation Components and Spring Malting Barley Yield by Residual Effect of Herbicides Used in Winter Rapeseed

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1 Reduction of Yield ORIGINAL Formation SCIENTIFIC Components PAPER and Spring Malting Barley Yield by Residual Effect of Herbicides Used in Reduction of Yield Formation Components and Spring Malting Barley Yield by Residual Effect of Herbicides Used in Czech University of Agriculture in Prague, Kamýcká 129, Prague 6 Suchdol, Czech Republic ( Becka@af.czu.cz) Abstract Using two types of soil preparation ( and non- system) and two levels of barley fertilization with nitrogen ( and kg N/ha) we established small plot trials with winter rapeseed in August with following combinations: 1) control without herbicide, 2) trifluralin +, ) trifluralin, ) alachlor +, ) metazachlor +. In spring we terminated the experiment by disk (simulation of winter rapeseed frost damage) and sew spring barley. In variant trifluralin + grain yield of barley decreased significantly (by 8%). The highest yield was obtained in variants: control without herbicide and metazachlor +. Key words: winter rapeseed, malting spring barley, herbicide residues, soil preparation, yield Introduction Harvest areas of the winter rapeseed in the Czech Republic range between 2 - ha. In the last years harvest areas slightly decreased. Besides economic reason for this decrease also high plowing in plays an important role in some years (2 - %, 2-16%), in average of the last years it is about 1%. High plowing in is mostly caused by bad over wintering (year 22/), problematic emergence in autumn due to drought (year 2/) or massive occurence of some autumnal pests (slug, turnip moth, flea beetle etc.) (Šedivý, 2). Substitution for plowed in rapeseed are often spring cereals, i.e. malting barley. Problem with herbicide residues used in rapeseed can happen easily, especially with shallow soil preparation. Barley emerges unevenly and its production abilities decrease (Vašák et al., 21). Štranc et al. (2) also present possibilities of minimalization establishing of spring cereals stands, i.e. spring barley with regard to used herbicide in forecrop, amount of winter precipitations, soil type and sort. According to Osmond in Kostrej et al. (1992) stress is every factor, which decreases growth and reproduction under required level. Such stress factors are also potential residues of herbicides. Plants response to this stress shows itself by decrease of yield. Materials and methods At the experimental station of Czech Agriculture University in Červený Újezd (altitude 98 m n. m., average year temperature 7.7 o C, year total of precipitations 9 mm, per vegetation 1.9 o C and 61 mm) we have established during 2/-26/7 experiments with herbicide residuals activity, which we applied to winter rapeseed at consequently sown malting barley. The experiment was sown at the end of August at two soil preparations (18-2 cm) and non- (up to 1 cm). In each soil preparation we applied four herbicide combinations and control, which are showed in Table 1. Other agrotechnical practices in rapeseed in autumn were: graminicide (twice), protection against voles and growth regulation. Winter rapeseed stand was in spring discontinued by disk (8-12 cm) by which we simulated frost damage of rapeseed. By sowing combination we sown into row of 9, cm of seeds of barley per m 2. For malting barley we chose cultivar Jersey. Barley was standardly treated: herbicide against dicotyledonous weeds Mustang (. l/ha), herbicide against monocotyledonous weeds - Puma Extra (.8 l/ha), fungicide (Artea EC-. l/ha), Proceedings. rd Croatian and rd International Symposium on Agriculture. Opatija. Croatia (7-77) XXX) Field Crop Production 7

2 Terpal C (1. l/ha). In each variant was used different nitrogen fertilization before seeding: and kgn/ha. Harmonogram of experiments: end of August-soil preparation for rapeseed and non-; end of August-winter rapessed sowing (8 seeds per m 2 ); end of August-herbicides application into rapeseed (Table 1); March-experiments with rapeseed discontinuation after winter (disk harrows); April-N fertilization ( and kgn/ha) and spring barley sowing ( seeds per m 2 ); end of July and beginning of August spring barley harvest. Table 1. Experimental Options, 2/ - 26/7 No. 1 2 Soil preparation for rapeseed non- non- non- non- non- N fertilization in spring barley (kg.ha -1 ) Herbicide variants for rapeseed Dose (l.ha -1 ) Control without herbicides - - trifluralin 8 g/l and g/l (tank mix) trifluralin 8 g/l 2. alachlor 8 g/l and 8 g/l (tank mix) metazachlor g/l + 8 g/l Application term -before sowing with embedding into -6 cm -before sowing with embedding into -6 cm -immediately after sowing on soil surface -immediately after sowing on soil surface Results and discussion Residual activity of herbicides used in winter rapeseed significantly influenced field emergence rate of consequently sown malting barley (Table 2). The worst emergence rate was found in variant 2 (trifluralin + ) 6.%, on the contrary the best emergence rate was in variants 1 (non-treated control) 72.9% and (alachlor + ) 66.7%. With herbicides trifluralin + field emergence rate decreased by 17% in comparison with non-treated control. Three years average shows, except variant that contributes significantly to decreasement of negative influence of herbicide residues and increases emergency. The largest amount of herbicide residues was decomposed due to in variant (metazachlor + ), that is difference in emergence rate 6.9%. The only variant, where emergence rate in barley was better (by 7.7%) in non- system was variant (trifluralin). The highest number of spikes was found in options (metazachlor + ) ( 622 spikes/m 2, non- 6 spikes per m 2 ) and (alachlor + ) ( 6 spikes/m 2, non- 67 spikes/m 2 ). The lowest number of spikes was found in variant 2 (trifluralin + ) ( 1 spikes/m 2, non- 79 spikes/m 2 ). In comparison with non-treated control in this variant with number of spikes decreased by 19% and in non- variant it was by 2% (Table and Graph 1). In variant barley formed more spikes in option and on the contrary in variants 1, 2, and barley formed more spikes in non- variant (Graph 1). Nitrogen fertilization influenced positively spikes formation in all monitored variants. The highest influence of nitrogen fertilization is in variant: 1 (nontreated control), (trifluralin) and (alachlor + ), Graph 2. Results in field emergence rate and observation during vegetation correspond to differences obtained in grain yield. Significant yield loss was found in variant 2 (trifluralin + ), which is statistically confirmatively different from other variants (Table ). Large yield differences are obvious between monitored years. The highest decreasement was in 26/7 due to long-term spring growth. Barley had bad emergence rate in this year and formed less generative organs. In comparison with previous years there was a 7 rd Croatian and rd International Symposium on Agriculture

3 Reduction of Yield Formation Components and Spring Malting Barley Yield by Residual Effect of Herbicides Used in significant decreasement in grain yield by.1 t/ha (in 2/) or by.26 t/ha (in 2/6). Soil preparation did not significantly influence seed yield. Difference is statistically nonconfirmative and it is. t/ha in favour of non- system. On the other hand in N fertilization we can see positive influence on yield (statistically confirmatively). Dose of kg N/ha before sowing increased yield by.89 t/ha (Table ). The highest grain yield was found in control (.7 t/ha, non-.7t/ha). The second most yielding variant with was variant (metazachlor + ).69 t/ha and in non- options it was variant (alachlor + ).88 t/ha. In variant 2 (trifluralin + ) was the highest yield decreasement in comparison with control, it was by 2.79 t/ha (it is %) in. Non- option did not have such significant decreasement in yield, it was by t/ha (it is %). Other variants have statistically non-confirmative differences (Graph ). Results correspond with conclusions of Kudrna-Vašák (2), which declare, that after some herbicides metazachlor+ there is no yielding decreasement in consequently sown spring barley. The worst emergence rate of spring barley, the worst yield formation elements and also yield decreasement is caused by herbicide combination trifluralin and (especially in non- systems). Graph shows, that nitrogen fertilization in all variants increased yield. The highest yield increasement was in variant due to N fertilization (trifluralin + ), it was by.28 t/ha. The highest thousand grains weight (TGW) was found in variant 2 (trifluralin + ).8 g (that is by 1% higher than control). This variant is statistically confirmatively different from other options. It is caused by compensation ability of barley, which had in this variant the lowest number of spikes per area unit. The lowest TGW was found in non-treated control (variant 1) 1. g. In grains moisture there is apparent negative influence of herbicides residues trifluralin + (variant 2), which prolonged vegetation and caused increasement of moisture in harvested grain. The lowest moisture was found in variants trifluralin (1.%) and alachlor + (1.%), Table. Table 2. Field Emergence Rate of Malting Barley (%) after Plowed in in Relation to Variant with Herbicide, Červený Újezd, 2/ - 26/7 Date average Soil preparation for rapeseed 1 control Field emergence rate (%) according to herbicide options 2 trifluralin + trifluralin alachlor + metazachlor non non non non average Table. Influence of Residual Effect of Herbicides Used in on Number of Spikes (spikes/m 2 ), TGW (g) and Grain Moisture (%) in Consequently Sown Malting Barley, Červený Újezd, 2/-26/, Tukey, 9% Variant Number of spikes TGW Grain moisture spikes/m 2 sig. g sig. % sig. 1-control 91.6 ab 1. a 1.8 ab 2-trifluralin + 6. c.8 b 1. a -trifluralin. b 2.7 a 1. c -alachlor a 2.2 a 1. c -metazachlor a 2.8 a 1.6 bc F-Ratio = 1.1 F-Ratio = 1.9 F-Ratio = 9.1 P-Value =. P-Value =. P-Value =. sig. (significantly different) different letters indicate that means are significantly different from others. Field Crop Production 7

4 9 9 8 non- 8 N kg/ha N kg/ha number of spikes 7 6 number of spikes trifluralin -alachlor + -metazachlor + 2 -trifluralin -alachlor + -metazachlor + Graph 1. Number of spikes (piece/m2) of malting barley based on soil preparation and herbicide variants, Červený Újezd, averages of years 2/-2/6, Tukey, 9%. Graph 2. Number of spikes (piece/m2) of malting barley based on N fertilization and herbicide variants, Červený Újezd, averages of years 2/-2/6, Tukey, 9%. Table. Statistical Evaluation of Malting Barley Yield (t/ha) after Plowed in in Relation to Variant with Herbicide, Year, Soil Preparation and N Fertilization, Červený Újezd, 2/ - 26/7, Tukey, 9% Variant t/ha sig. Year t/ha sig. Soil preparation t/ha sig. N fertilization t/ha sig. 1-control.79 a 2/ 6.8 a.19 a N kg/ha.992 a 2-trifluralin +.1 b 2/6.99 b non.21 a N kg/ha.81 b - trifluralin.88 a 26/ c -alachlor +.6 a -metachlor +.66 a F-Ratio = F-Ratio = 62.8 F-Ratio =. F-Ratio = 1.8 P-Value =. P-Value =.1 P-Value =.86 P-Value =.1 sig. (significantly different) different letters indicate that means are significantly different from others. 7 6, non- 7 6, N kg/ha N kg/ha 6 6 grain yield (t/ha),, grain yield (t/ha),,,, 2, -trifluralin -alachlor + -metazachlor + 2, -trifluralin -alachlor + -metazachlor + Graph. Grain yield (t/ha) of malting barley based on soil preparation and herbicide variants, Červený Újezd, averages of years 2/-26/7, Tukey, 9%. Graph. Grain yield (t/ha) of malting barley based on N fertilization and herbicide variants, Červený Újezd, averages of years 2/-26/7, Tukey, 9%. 76 rd Croatian and rd International Symposium on Agriculture

5 Reduction of Yield Formation Components and Spring Malting Barley Yield by Residual Effect of Herbicides Used in Conclusions Results of our experiments show, that residues of some herbicides used in rapeseed significantly decrease emergence rate, yield formation markers and yield of consequently sown malting barley. Herbicide variant (trifluralin+) with its residues significantly decreased field emergency rate (by 17%), number of spikes (by 21%) and malting barley yield (by 8%) in comparison with non-treated control. Soil preparation does not have significant influence on seeds yield, non- system is better (by. t/ha). On contrary dose of kgn/ha before sowing increased yield by.89 t/ha. Barley harvested in variant with trifluralin + had the highest TGW (by 1%) and grain moisture (by 1%). References Kostrej, A. a kol. (1992). Fyziológia porastu poľných plodín, VŠP, Nitra. Kudrna, T., Vašák, J. (2). Nahrazování zaorané řepky jarním ječmenem. (-1) In: Kompendium vybraných poznatků při pěstování sladovnického ječmene, ČZU, Praha, 1 s. Šedivý, J. (2). Škůdci ozimé řepky. (199-22) In: Vašák, J. a kol. (2) Řepka. Agrospoj, Praha, 22 s. Štranc, P., Vašák, J., Barcal, O. (2). Možnosti využití náhradních plodin po vyzimované řepce. (6-6) In: Sborník - Řepka, mák, hořčice. Praha: Česká zemědělská univerzita v Praze, 2, 188 s. Vašák, J., Nerad, D., Mikšík, V. (21). Doporučení k ochraně ozimé řepky a nové poznatky. Agro, č., This project was financially supported by the grant CIGA Determination of Residual Effect of Herbicide on Yield Components, Yield and Quality of and Malting Barley and the internal grant Impact of Herbicide Residues on the Yield Components and Quality in. sa28_1 Field Crop Production 77