Voi 4:429-443. Benefit of using plant growth regulators in fodder barley Leila-Riitta Erviö and Heikki Jalli Agricultural Research Centre ofFinland, Institute ofPlant Protection, FIN-31600 Jokioinen. Finland Markku Kontturi Agricultural Research Centre ofFinland, Institute ofCrop and Soil Science Heikki Hakkola Agricultural Research Centre of Finland, North Finland Research Unit Arjo Kangas Agricultural Research Centre of Finland, West Finland Research Unit Paavo Simojoki Agricultural Research Centre ofFinland, East Finland Research Unit The study was conducted to investigate the effect and benefit of applying plant growth regulators (PGR) to two easily lodging barley cultivars, Arra and Kilta, which were commonly used for fodder production all over Finland. Field trials were conducted at six experimental sites in different parts of the country. Of the PGRs tested, ethephon and mepiquat/ethephon were the most effective in shorten- ing the culm and preventing lodging. However, neither could prevent the lodge adequately in all growing circumstances. When applied at flag-leaf stage (FS 10) they increased yield under condi- tions favourable for lodging. They also raised the volume weight of barley, which was important for the final price of the yield. The most important factors determining future lodging of barley were an effective temperature sum of over +5°C and precipitation during the period from sowing to the begin- ning of tillering (FS 2). About 64-68% of the lodging risk of the cultivars studied could be predicted from weather conditions during early development of the crop. Local growing conditions and the presence of lodge had a marked impact on the results obtained with PGRs. In the case of moderate lodging the compound used determined whether a profit or loss was made on the crop. In the case of heavy lodging, compounds containing ethephon contributed to an economic return. Their application at flag-leaf stage gave a profit of FIM 70 - 390 ha 1 . Since the profitability of PGR treatments de- pended on lodging, treatments are recommended for fodder barley only when lodging is expected. The lodging risk can be predicted within certain limits at the tillering stage of barley. Key words: profitability, ethephon, chlormequat, mepiquat, lodging, prognosis, weather factors, yield components, yield © Agricultural Science in Finland Manuscript received December 1994 429 AGRICULTURAL SCIENCE IN FINLAND https://www.c-info.fi/en/info/?token=Udq_xwOZrj1iLqby.2ZxtWnPpJd-gNaGS0A7Pdg.jEUDa4x6U5jETd4bJ7skIClFsoIYGXsxPulTLivWYg6Q3MLb1BpTx8yvbsC4U3M0i1A8ueNY8AAecVb-tTLChDB1bnPhu7t665umOH0FDMPAqgg_wCoVcQzi7_j7cIJ5aUH-NvCFg0iyd24_pogvIz7q2O7TNYaBQduXWSh0NYGhyVX5S7qKsjFqEtawxOL2v_u2fAJQUHRsWaJD2wC7QqXiufg3tGX1hnYHn4IHIS4rBSegnXcKPEF7pg0VJY20F7QETonwzGNYdeg13dM8un06ZAsOqHnJCj6K3C3bpZqDWA73PJT5zbcmROXy8gQf14TRCjSLqxtRlojDOvTV5IRxx5VeBrv4ITWzNEj6v3tCC6iCkjIovj_Ou70q Erviö, L.-R. etal: Benefit ofusing plant growth regulators infodder barley Introduction Treating growing cereals with plant growth reg- ulators (PGR) is an established way of prevent- ing lodging and of securing the yield. The range of compounds available for that purpose has in- creased during the last decade and they now pro- vide good prospects for growth regulation at dif- ferent developmental stages of the crop (Wiin- sche 1977, Woolley 1981, Karpenstein and Scheffer 1984). If the rates of growth substances in crop plants could be manipulated at a cer- tain developmental phase, the yield formation could be regulated as desired at the same time (Bruckner and Höfner 1980, Scheffer et al. 1983). The PGRs available for cereal crops in Fin- land are chlormequat chloride (CCC, several products), and ethephon both as such (‘Cerone’) and in a mixture with mepiquat (‘Terpal’). CCC has not been satisfactory in preventing lodging of six-row barley under Finnish conditions. When compounds containing ethephon first came on the market, they were expected to be effective in preventing lodging of barley. The need was great, especially for six-row fodder barley in central and northern Finland, where early cultivars, which always have a tendency to lodging, are important. Lodging is further pro- moted in these areas by the growing conditions, in particular by the high light intensity and high soil moisture content. Synergistic effects of growth regulators in mixtures have been reported in some studies (Scheffer et al. 1983, Jung et al. 1987). Simulta- neous use of two or more PGRs has reinforced theirreducing effect on culm length (Höfner and Kiihn 1982), promoted shoot survival (Scheffer et al. 1983) and significantly increased ears m 2 (Ma and Smith 1991). CCC has usually been one component in the mixtures. By exploiting the synergistic effects of PGRs in mixtures one might be able to cut costs in practical farming, as the effect of a cheaper compound could be enhanced by adding a small amount of a more effective, but more expensive, product. From the economic point of view, the treat- ments should be cost effective for the produc- tion of fodder. Many studies have shown that the profitability of using PGRs on barley depends on the presence of lodging (Woolley 1981, Her- bert 1983, Moes 1990). Since PGRs have to be applied between the shooting and flag-leaf stages of barley, it is important to be able to asses the probability of future lodging and the need for PGR treatments. The objectives of this study were to develop a method for predicting lodging at early stages of barley growth, to examine the effect of PGRs on preventing lodging, and on yield and yield components of early spring barley cultivars in different environments. The profitability of us- ing PGRs in fodder barley production was also evaluated. Some tank mixtures of ethephon and chlor- mequat were also studied to establish the bene- ficial synergistic effects of PGRs in regulating the lodge resistance of culms and the develop- ment of yield components. Material and methods Field trials The study was conducted by the Institute of Plant Protection (KSL) of the Agricultural Research Centre located at Jokioinen in southern Finland. In addition five research stations took part in the investigation. They were Satakunta (SAT) in southern Finland, Laukaa (LAU) and South Os- trobothnia (EPO) in central Finland and Toho- lampi (TKP) and North Ostrobothnia (PPO) in northern Finland. Since growing conditions varied from one site to another, data on soil and nutrition proper- ties in the field trials and on weather conditions at the experimental locations are presented in Tables 1 and 3. Six to ten PGR treatments as listed in Table 2 were studied in field trials at each experimen- 430 AGRICULTURAL SCIENCE IN FINLAND Vol. 4: 429^443. tal site. The plot size was 30 m 2 at Jokioinen (KSL) and 20 m 2 at the other sites. Each treat- ment was accomplished with four replicates. In 1985-87 the trials were arranged in a ran- domized block design with one nitrogen level determined as typical of local farming practice (Table 1). In 1988-89, two levels ofnitrogen fer- tilization were included in the trial programme. The higher level (N 2 ) was typical of local farm- ing practice and the lower level (N,) was half of that (Table 1). The trials were laid out in a split- split-plot design using cultivars as the main plots and nitrogen levels as the sub-plots. The six-row spring barley cultivars Arra and Kilta were cho- sen as the targets of study because of their ten- dency to lodging and widespread use for fodder production troughoutFinland. The seeding rate was 500kernels nr2 . The seeds were treated with fungicides against plant diseases. PGR treatments The active ingredients ha' 1 and timing of the PGR treatments are listed in Table 2. The compounds were applied with a gas-powered “van der Weij”- type sprayer, provided with a wind shield and flat nozzles. The water volume was 200 I ha 1 and spraying pressure 300 kPA. The study was started before ethephon-con- taining compounds were approved for market- ing in Finland. The doses of ethephon and CCC used in the first year proved to be unnecessarily high and were lowered in succeeding years (Table 2). The studied doses of ethephon and mepiquat/ethephon correspond to the highest rates currently recommended for easily lodging barley cultivars. Assessments and yield components After the crop had emerged, a sample area of one row metre was marked on each plot. Emerged barley plants in these areas were count- ed and collected before harvest for yield com- ponent analyses. The number and weight of culms and ears, the number and weight of grains per ear, the proportion of green grains in the yield and the harvest index (HI) were determined for the samples. HI is the ratio of grain yield to to- tal dry matter above ground. Table 1.Data on field trials at different locations in 1985-89. Locations: KSL = Institute of Plant Protec- tion and experimental stations SAT = Satakunta, LAU = Laukaa, EPO = South Ostrobothnia, TKP = Toho- lampi, PPO = North Ostrobothnia. KSL SAT LAU EPO TKP PPO Number of trials on different soil types: - coarse mineral soil 0 14 10 8 8 5 -clay 14 0 1 6 0 0 - organic 0 0 0 0 4 2 pH (H20) 5.8-63 5.9-6.2 5.1-6.1 5.4-6.7 5.4-5.9 5.4-6.5 Fertilization kg ha 1 -N," 60 50 53 60-80 50-64 50-58 -N2 " 120 100 96-100 120 100-128 100-117 -P 21 12-24 50-54 23-53 23-35 23-80 18-44 -K 24-48 102-133 44-100 45-65 45-144 35-81 1) 1988-89 N 2 in 1985-87 and 1988-89 2) According tosoil type 431 AGRICULTURAL SCIENCE IN FINLAND Erviö, L.-R. et al: Benefit ofusing plant growth regulators in fodder barley Table 2. Treatments of plant growth regulators in barley 1985- 89, Time I=beginning of tillering (FS 2), ll=l-node stage (FS 6), lll=flag-leaf stage (FS 10) (Large 1954). Treatments Dose a.i Treatment time Nitrogen 1 ha' 1 Feekes Scale level 1985 1986-87 1. Untreated - N 2 2. CCC 0.4 0.2 IFS 2 N 2 3. 1.5 0.5 II FS 6 N 2 4. CCC+mepiquat 1.5+0.4 0 5+0.1 II FS 6 N 2 5. CCC+ethephon 1.5+0.3 0 5+0.1 II FS 6 N 2 6. ethephon 0.7 0.35 II FS 6 N 2 7. mepiquat/ethephon 0.46/0.23 0.46/0.23 II FS 6 N 2 8. CCC+ethephon 1.5+0.3 0.5+0.1 111 FS 10 N 2 9. ethephon 0.7 0.35 111 FS 10 N 2 10. mepiquat/ethephon 0.46/0.23 0.46/0.23 111 FS 10 N 2 1938-89 [.Untreated - - NI.N2 2. CCC 0.2 I FS 2 NI.N2 3. CCC 0.5 II FS 6 NI,N2 7. mepiquat/ethephon 0.46/0.23 II FS 6 NI,N2 9. ethephon 0.35 111 FS 10 NI.N2 10. mepiquat/ethephon 0.46/0.23 111FS 10 NI,N2 Water volume 200 1/ha. The height of the stand was measured at the stage defined as milky rape 11.1 on the Feekes scale (FS) (Large 1954) at five places per plot. The height representing the majority of the culms in the stand was measured from the soil surface to the awn tops. The first date of lodging was recorded. Immediately before harvest, lodging was visually assessed on a scale of 0 - 100% (o=no lodge, 100=completely lodged), taking into account the angle of culms and the lodged area of each plot. The crops were harvested with a combine, when ripe for cutting (FS 11.4), and the grain yield per plot was weighed. Volume weight (kg hi 1), grain moisture at harvest, kernel weight (mg) and grain protein concentration (%) were determined on the harvested yield with standard methods to establish the price of the grain yield. No plant diseases were observed. Weed con- trol was applied if necessary. Predicting lodging To establish which factors predict future lodg- ing of barley, the data on mean temperature, ef- fective temperature sum (ETS) over o°, +2° and +5°C and precipitation (PR) recorded at differ- ent time intervals during the growing period of barley were studied in relation to lodging by regression analysis. Statistically significant (P=0.15) variables were included in the regres- sion equation one by one and the equation was recalculated until no more significant variables remained. Profitability of treatments The economic return on PGR treatments was measured by the monetary profit obtained from the yield at the price level of spring 1992. The 432 AGRICULTURAL SCIENCE IN FINLAND Vol. 4: 429^43. calculation was based on a yield with 15% mois- ture content using the price of fodder barley, FIM 1.82 kg ', minus a marketing cost of FIM 0.30. The yield price was corrected if necessary, ac- cording to the volume weight. The cost of spray- ing with hired equipment FIM 50 ha' 1 (Työteho- seuran maataloustiedote 1992) and the price of PGRs depending on the compound, were deduct- ed from the yield profit. Because of the step-up scale used for the market prices of PGRs, the cost of treatments fluctuated considerably dur- ing the year. Here the following costs per ha were applied: CCC 0.2 1 ha 1 FIM 29, CCC 0.5 I ha 1 FIM 81, CCC+mepiquat FIM 227, CCC+ethe- phon FIM 129, ethephonFIM 169 and mepiquat/ ethephon FIM 201. The nitrogen level N, cost was FIM 82 and that of N 2 FIM 155 ha 1 . The price of the yield corresponding to 100 kg ha* 1 as trampling losses (Köylijärvi 1985) was de- ducted from the profit of flag-leaf stage treat- ments. Statistical analyses The material showed that the lodging rate in untreated plots of different trials varied widely without any clear connection with the year or the geographical location of the experimental site. To eliminate this kind of variation the data obtained in 1985-87 were classified according to the rate of lodging in untreated plots into the following three groups: 1 = lodging 0-25% 2 = " 26-70% 3= " 71-100% The majority of the trials in 1987 were as- signed to class 3, whereas some trials in other years fell in all classes. Owing to the small size of the data set for 1988- 89, it could not be classified in the same way. The effects ofPGR treatments, nitrogen lev- els and cultivars and their interactions were es- tablished by analysis of variance. The signifi- cance of the differences between the means was tested by Tukey’s test (HSD, P=0.05). Weather conditions in growing seasons 1985-89 Weather conditions varied considerably between sites and years (Table 3), The most unfavourable year was 1987, which as a whole, was cold and rainy. Early May 1985 was rather cool and night frosts occurred. Growing seasons 1986 and 1988 began early and warm weather favoured plant developement. In 1989, the weather was cool at the begin- ning of plant growth. Later on, the growing sea- son turned warmer and, as a whole, was favour- able to the growth of crops. Showers were typical of the whole study pe- riod causing considerable variation in precipita- tion between the experimental sites. Thus the stands suffered drought or excessive wetting, depending on the location of the trial. Results Factors affecting lodging The main growing factors affecting lodging were effective temperature sum (ETS) over 5°C and precipitation (PR, mm) during the time between sowing and beginning oftillering (FS 2). Weather conditions during this time explained 64% (P > 0.0001) of the lodging of Arra according to the equation; Lodging = 992.716 - 10.510 x ETS + O.O2B(ETS)2 + 0.008(PR) 2. 68% (P > 0.0002) of the lodging ofKilta was explained by the equa- tion: Lodging = 1071.853 - 11.567 x ETS + 0.031 (ETS)2 + O.OIO(PR)2 . Thus, 64-68% of the risk of lodging can be predicted by weather conditions during the pe- riod in question. The weather factors of other growing season intervals included in the model did not raise its explanatory level. However, lo- cal showers in late summer increased the lodg- ing of barley and gave a rising trend to the fig- ures (Fig. 1). The highest values for weather fac- tors in the figures are calculatory; being extra- 433 AGRICULTURAL SCIENCE IN FINLAND Erviö, L.-R. et ai: Benefit ofusing plant growth regulators infodder barley Table 3. Effective temperature sum (ETS, base +5°C), cumulative precipitation (PR, mm) and prognosis for lodging of cv. Arra and Kilta in the 1985-89 growing seasons at different locations. The lower N level is omitted. 1 = time interval between sowing date and first PGR treatment of the crop, 2 = interval from beginning of growing season to 1 September, when 70% of the trials were harvested. + =risk based on ETS or PR, ++ = risk based on combination of ETS and PR, - = no risk. Locations: KSL = Institute of Plant Protection and experimental stations SAT= Satakunta, LAU = Laukaa, EPO = South Ostrobothnia, TKP = Toholampi, PPO = North Ostrobothnia. Site and year ETS °C/PR mm Prognosis of lodging Occurred lodging % 1 2 Arra Kilta Arra Kilta KSL 1985 162/45 1027/238 ++ ++ 0 0 1986 173/40 1138/244 ++ - 0 0 1987 160/73 831/269 ++ ++ 69 47 1988 217/27 1268/275 ++ + 8 0 1989 162/30 1146/277 ++ + 56 0 SAT 1985 138/30 1037/202 ++ + 91 89 1986 142/12 1128/195 + + 55 46 1987 136/74 824/320 ++ ++ 97 96 1988 157/83 1238/320 ++ ++ 45 71 1989 176/83 1153/257 + + 65 85 LAU 1985 196/45 987/266 + - 0 0 1986 213/43 1074/311 ++ 1) 25 1) 1987 180/96 775/371 + 1) 79 1) 1988 186/55 1162/338 + + 0 0 1989 197/56 1098/307 + + 58 II EPO 1985 190/51 982/189 + + 26 0 1986 169/34 1066/242 ++ - 6 15 1987 141/58 766/166 ++ ++ 90 93 1988 174/60 1168/297 ++ + 62 75 1989 183/76 1116/274 + + 34 45 TKP 1985 181/39 931/231 + - 22 2 1986 235/11 1030/259 + + 71 69 1987 1) 770/306 1) 1) 1) 1) 1988 144/37 1103/347 + + 23 14 1989 156/82 1042/492 ++ + 88 65 PPO 1985 172/31 886/228 ++ 1) 31 1) 1986 178/71 956/275 + 1) 65 1) 1987 158/66 728/305 ++ 1) 94 1) 1988 133/19 1072/223 + 1) 56 1) 1989 160/84 1000/324 ++ 1) 66 1) 1) No trial polated from the equations they cannot be con- sidered realistic. According to the model, the risk of lodging in Kilta was generally lowest (0-5%) when the ETS was 165°-215°C and precipitation below 45 mm. Arra has a persistent tendency to lodg- ing. The lowest rates of lodge (0-5%) can be ex- pected between ETS 175° and 200°C when the precipitation is below 25 mm. The combination of ETS and PR during the risky period (Table 3) indicated a risk of lodge for either cultivar every year at KSL, and in 1987 at SAT, EPO and PPO; 1988 was risky at SAT and EPO, and 1989 at TKP and PPO. On the basis 434 Vol. 4: 429^43. of temperature or precipitation lodging could be expected in several years at different locations. Most of the observed occurrences of lodging matched the prognosis; only 11 out of 51 assess- ments (i.e. 22%) failed. Effect of variety and treatments In terms of lodging and yield properties the in- teractions between cultivars and treatments were not significant. Kilta had a higher kernel weight and harvest index than Arra; it also produced a higher yield and had more grains per ear than Arra. However, withincultivars each PGR treat- ment had a similar effect on these properties. In consequence, the data on the effect oftreatments were pooled across the cultivars separately for 1985-87 and 1988-89. Height and lodging The treatments with mepiquat/ethephon and ethephon alone or in mixtures decreased culm height in all classes from 5 to 14 cm in 1985-87 (Fig. 2). Applications at flag-leaf stage were most effective. The effect of CCC on culm length was not significant. Considerable lodging (> 25%) occurred in 62% ofall trials, and 26% of the cases were se- verely (> 70%) lodged. On the basis of classifi- cation 1 -3, lodging was most severe in the third group in 1985-87. The late applications of mepi- quat/ethephon and ethephon, which significant- ly shortened the culm height were the most ef- fective in preventing lodge. However, not even they could prevent lodge adequately in the worst cases. At different N levels, all applications except the earliest CCC treatment shortened barley in 1988-89 (Fig. 3). Lodging was prevented most effectively with late applications of mepiquat/ ethephon, ethephon and the CCC+ethephon mix- ture at both nitrogen levels. Grain yield, weight and protein concentration In 1985-87 significant differences between treat- ments in the yield of barley were observed only in class 3, in which the latest applications of mepiquat/ethephon and ethephon increased the yield by 350 and 480 kg ha 1 , respectively (Fig. 4). Fig. 1. Lodging prognosis for cvs. a) Arra and b) Kilta based on the effective temperature sum and precipitation between sowing date and beginning of tillering (FS 2) ofbarley. 435 AGRICULTURAL SCIENCE IN FINLAND Erviö, L.-R. et al.: Benefit ofusing plant growth regulators infodder barley Fig 2. Effect of PGR treatments on height and lodging of barley in 1985-87. a) class I, b) class 2, c) class 3. Means of treatments followed by the same superscript letter in each class are not significantly different at level P = 0.05. Treatments: 1 = untreated, 2 = CCC, time I, 3 = CCC 11, 4 = CCC+mepiquat 11, 5 = CCC+ethephon 11, 6 = ethephon 11, 7 = mepiquat/ethephon 11, 8 = CCC+ethephon 111, 9 = ethephon 111, 10 =mepiquat/ethephon 111. 436 AGRICULTURAL SCIENCE IN FINLAND Vol. 4. 429^443. Fig. 3. Effect of PGR treatments on height and lodging of barley at different N levels in 1988-89, Means of treat- ments followed by the same superscript letter at each N level are not significantly different at level P = 0.05. Treatments: 1 = untreated, 2 = CCC time 1,3 = CCC 11, 7 = mepiquat/ethephon 11, 9 = ethephon 111, 10 = mepiquat/ ethephon 111. The average grain protein concentration was 14.8%. Only early application of ethephon low- ered it significantly in classes 1 (14.2%) and 3 (13.4%). Treatments did not affect the yield of barley at either nitrogen level in 1988-89. Compared with untreated plots early mepiquat/ethephon ap- plication decreased the volume weight, the ker- nel weight, and the grain protein concentration at both nitrogen levels (data not given). Grain volume weight and kernel weight were influenced by the treatments in different ways, depending on the lodging classification (Fig. 5). In the event ofsevere lodging (class 3), late treat- ments with ethephon compounds increased the volume weight, which was important for the price of the yield. Yield components and grain moisture In 1985-87, late application of ethephon de- creased the weight of ears in class 1. In class 3, treatments usually raised the HI and grain number per ear (data not given). The treatments had no effect on the other yield components measured or on the proportion of green grains. Fig. 4. Effect of PGR treatments on yield of barley in class 3 in 1985-87. Means of treatments followed by the same superscript letter are not significantly different at level P = 0.05. Treatments: 1 = untreated, 2 = CCC, time I, 3 = CCC 11, 4 = CCC+mepiquat 11, 5 = CCC+ethephon 11, 6 = ethephon 11, 7 = mepiquat/ethephon 11, 8 = CCC+ethephon 111, 9 = ethephon 111, 10=mepiquat/ethephon 111. 437 AGRICULTURAL SCIENCE IN FINLAND Erviö, L-R. et al.: Benefit of using plant growth regulators infodder barley Fig. 5. Effect of PGR treatments on volume weightand kernel weight ofbarley in 1985-87. a) class 1 , b)class 2, c) class 3, Means of treatments followed by the same superscript letter in each class are not significantly different at level P = 0.05. Treatments: 1 = untreated, 2 = CCC, time I, 3 = CCC 11, 4 = CCC+mepiquat 11, 5 = CCC+ethephon 11, 6 = ethephon 11, 7 = mepiquat/ethephon 11, 8 = CCC+ethephon 111, 9 = ethephon 111, 10 = mepiquat/ethephon 111. 438 AGRICULTURAL SCIENCE IN FINLAND Vol. 4: 429-443. Grain moisture varied from one class to an- other, usually being lowest in group 1 and high- est in group 3 (data not shown). Significant mois- ture differencesbetween treatments could not be reliably tested because of the low number of observations in each group. According to the field assesments ethephon delayed the ripening of barley by about one day. In 1988-89, small differences between treat- ments occurred in the number of ear-bearing culms, grains per ear and HI but they were not significant when compared with untreated plants at either nitrogen level (data not given). Profitability of treatments The use of PGRs was not profitable under the conditions existing in class 1 (Fig. 6). Only the early application of chlormequat gave a favour- able result. In class 2, with variable lodging, the PGR treatments resulted in a profit or loss depending on the compound used. The best result was achieved with a mixture of CCC+ethephon ap- plied at the 1-node stage (FS 6). Treatment with ethephon at the flag-leaf stage (FS 10) was the least profitable. Fig. 6. Profitability of PGR treatments in different classes in 1985-87.a) class 1, comprises 11 trials, b)class 2, 6 trials, c) class 3, 11 trials. Treatments: 1 = untreated, 2 = CCC, time I, 3 = CCC 11, 4 = CCC+mepiquat 11, 5 = CCC+ethephon 11, 6 = ethephon 11, 7 = mepiquat/ethephon 11, 8 = CCC + ethephon 111, 9 = ethephon 111, 10 = mepiquat/ethephon 111. 439 AGRICULTURAL SCIENCE IN FINLAND Erviö, L.-R. etal: Benefit ofusing plant growth regulators infodder barley Under the growth conditions represented by class 3, which resulted in heavy lodging, the PGRs containing ethephon contributed to an eco- nomic return. In this class the volume weight of the yield generally remained low. Consequent- ly, with the exception of the applications at flag- leaf stage (FS 10), the quality of the yield was below the requirements for marketing, and the calculatedprofit (Fig. 6) on other treatments was not realistic. The profit achieved with different ethephon compounds at flag leaf stage varied from FIM 70 to 390 per ha. In 1988-89, a small profit was achieved at the lower N level only with the earliest CCC treatment (FS 2) (Fig. 7). At the higher N level, PGR treatments to the 1-node stage (FS 6) of barley were profitable. Despite the better pre- ventive effect on lodging, later use of ethephon and mepiquat/ethephon resulted in financial loss. Discussion Lodging The results obtained with PGRs depended to a considerable extent on local growing conditions and in particular on the presence of lodging risk. This has been shown by several other workers, too (Woolley 1981, Caldwell et al. 1988, Her- bert 1983,Simmons et al. 1988, Ma et al. 1992). In the absence of lodging the use ofPGRs, ethe- phon compounds in particular, might even have an adverse effect on barley. Thus some Cana- dian results suggest that ethephon should only be used when there is a high risk of severe lodg- ing (Moes 1990, Moes and Stobbe 1991). Of plant growth regulating factors temper- ature and precipitation data are readily availa- ble to farmers. These were therefore chosen as factors which could be used to forecast the fu- ture lodging ofbarley and the need for PGR treat- ments. The most important factors for future lodg- ing turned out to be ETS over +5°C and the PR between sowing date and the beginning of till- ering (FS 2) of the crop. By influencing the growth intensity and development of the crop stand they affect its tendency to lodge. ETS cor- responds to the mean temperature of the time interval measured(Lallukka et al. 1978) and thus the prevailing temperature level. Weather conditions affecting lodging after the flag-leaf stage and the last treatment are not pre- dictable. Heavy local showers from late July to harvesting are typical ofFinnish conditions and cause uncertainty in prognose. This was seen in the explanatory levels of the equations, 64% for Arra and 68% for Kilta. In our study, the predicting future lodging by weather factors (Fig. 1) during early crop development matched well the reality in these limits (Table 3). Yield and yield components Early CCC application was not observed to in- crease tillering in this study, even at the higher nitrogen level used with success in some inves- tigations (Höfner and Kilhn 1982,Scheffer et al. 1983).On the other hand, the inefficacy of early CCC treatments has also been reported (Wad- dington and Cartwright 1986, Steen and Wiin- sche 1990). The lack ofincreased tillering in our Fig. 7. Profitability ofPGR treatments at different N levels in 1988-89. ■ N,, comprises 22 trials, ■ N 2, 22 trials. Treatments: 1 = untreated, 2 =CCC time I, 3 =CCC II, 7 = mepiquat/ethephon 11, 9 = ethephon 111, 10 = mepiquat/ ethephon 111. 440 AGRICULTURAL SCIENCE IN FINLAND Vol. 4: 429^43. study might be attributed to the rapid develop- ment of plants under Finnish conditions. Owing to the long day, tillering lasts for about two weeks, which is probably too short for the crop plant to produce several tillers (Kivi 1967). In general, no particular yield component was seen to clearly contribute to yield development. Consequently, the yield increase achieved with late applications of ethephon and mepiquat/ ethephon in group 3 may have been due to the prevention of lodge. Our results are supported by other studies in which the effect of PGRs on yield components varied between years and cul- tivars, hampering the identification of a single component as the major consistent factor (Ma and Smith 1991a, Ma et al. 1992). The synergistic effect of PGR mixtures on the yield or yield components ofbarley reported in some studies (Karpenstein and Scheffer 1984, Ma and Smith 1991a) was not significant in our experiments (Fig. 4). This was in accordance with the investigations of Caldwell et al.( 1988) who found that suchresults depended on the year and on the sensitivity ofbarley cultivars to PGRs. Profitability of using PGRs The profitability of growth regulator treatments depended on the amount, quality and price of the grain yield and the price of the PGR used. For example in classes 1 and 2, CCC treatment alone and, in class 2, CCC plus one tank mixture showed a slight profit due to their low costs (Fig. 6) since no significant yield differences existed between treatments. The same was noted in the trials at different N levels (Fig. 7). Under stress- ing growing conditions with heavy lodging all the treatments seemed to be more or less profit- able. In reality, though, only three treatments, those with ethephon compounds and a mixture at flag- leaf stage, were profitable as the quality of the yield was poor with the other treatments. Our study indicated that there is no financial gain to be obtained from using expensive PGRs in fodder barley unless the risk of lodging is really heavy. Profit was obtained with PGRs only when lodging was prevented or delayed. The same has been found in many previous studies (Woolley 1981, Herbert 1983, Simmons et al. 1988, Moes 1990). Ethephon treatments of fod- derbarley have given both profitable and unprof- itable results in other experiments carried out by the experimental stations of the Agricultural Research Centre ofFinland (Kangas 1993). The wide variation in the performance of PGRs is thus well recorded. Acknowledgements. We thank the heads of the regional experimental stations of the Agricultural Research Centre, Ms. Sirkka-Liisa Hiivola, Mr. Aulis Järvi and Mr. Heikki Talvitie for participating in this study and for putting both their expertise and their facilities at our disposal. References Bruckner, U. & Höfner, W. 1980. Increased shortening and yield increase by combined application of the growth regulators CCC and ancymidol to springwheat. Zeitschrift fur Acker- und Pflanzenbau 149: 251-257. Caldwell, C. 8., Mellish, D. R. & Norrie, J. 1988. A comparison of ethephon alone and in combination with CCC or DPC applied to spring barley. Canadian Journal of Plant Science 68: 941-946, Höfner, W. & Kiihn, H. 1982. Effect of growth regulator combinations on ear development assimilate transloca- tion and yield in cereal crops. Proceeding of Easter School in Agricultural Science 33: 375-390. Herbert, C. D. 1983. Interactions between nitrogen fer- tilizers and growth retardants in practical cereal produc- tion. British Plant Growth Regulator Group, Monograph 1983, 9: 87-95. Jung, J., Luib, M., Sauter, H., Zeeh, B. & Rademacher, W. 1987. Growth regulation in crop plants with new types of triazole compounds. Journal of Agronomy and Crop Science 158: 324-332. Kangas, A. 1993. Kokemuksia kasvunsääteidenkäytöstä Etelä- Pohjanmaalla. Kasvinsuojeluseuran kasvinsuoje- lupäivät 1993, p. 30-33, Karpenstein, M. von & Scheffer, K. 1984. Die ertrags- 441 AGRICULTURAL SCIENCE IN FINLAND Erviö, L.-R. et al: Benefit ofusing plant growth regulators infodder barley und wachstumsbeeinflussenden Wirkungen eines Wach- stumsregulators auf der Basis von Mepiquatchlorid und etephon auf zwei Sommergerstensorten bei differenzi- erter N-Dungung. Landwirtschaftliche Forschung 37: 3- 4. Kivi, E. 1967. Ilmastotekijäin vaikutus mallasohrasadon määrään ja laatuun. Mallasjuomat 1967: 295-317. Köylijärvi, J. 1985. Ruiskutusten tallaustappiotviljakas- vustoissa. Koetominta ja Käytäntö 42: 32. Lallukka, U., Rantanen, O. & Mukula, J. 1978. The tem- perature sum requirements of barley varieties in Finland. Annales Agriculturae Fenniae 17: 185-191, Large, E. C. 1954. Growth stages in cereals. Illustrations of the Feekes scale. Plant Pathology 3: 128-129. Ma, B. & Smith, D. 1991a.The effects of ethephon,chlor- mequat chloride and mixtures of ethephon and chlorme- quat chloride applied at the beginning of stem elonga- tion on spike-bearing shoots and other yield components of spring barley (Hordeum vulgäre L.). Journal of Agro- nomy and Crop Science 166: 127-135. - & Smith D. 1991b. Apical Development of spring bar- ley in relation to chlormequat and ethephon. Agronomy Journal 83: 270- 274. Leibovitch, S., Maloba, W. E. & Smith, D. L. 1992. Spring barley responses to nitrogen fertilizer and ethe- phon in regions with short crop growing season. Journal of Agronomy and Crop Science 169: 151-160. Moes, J. 1990. Assimilate partitioning, tillering and yield components in barley treated with ethephon. Disserta- tion Abstracts International B, Sciences and Engineering 51, 3: 1049- B. - & Stobbe, E. H. 1991. Barley treated with ethephon. I. Yield components and net grain yield. Agronomy Jour- nal 83: 86-90. Scheffer, K., Dippel.V., Hartung,E. G. & Karpenstein, M. 1983. Der Einfluss eines Wachstumregulators auf Ertrag und Ertragskomponenten bei Sommergerste un- ter Ausschaltung von Lager. Zeitschrift fur Acker- und Pflanzenbau 152: 284-292. Simmons, S. R., Oelke, E. A., Wiersma, J. V., Lueschen, W. E. & Warnes, D. D. 1988. Spring wheat and barley responses to ethephon.Agronomy Journal 80: 829-834. Steen, E. & Wunsche, U. 1990. Root growth dynamics of barley and wheat in field trials after CCC application. Swedish Journal of Agricultural Research 20; 57-62. Työtehoseura 1992. Maatalouskoneiden vuokrasuo- situkset 1992. Työtehoseuran maataloustiedote 8/1992. 8 p. Waddington, S. R. & Cartwright, P. 1986. Modification of yield components and stem length in spring barley by the application of growth retardants prior to main shoot stem elongation. Journal of Agricultural Science 107: 367-375. Woolley, E. W. 1981. Performance of Current growth regulators in cereals. British Plant Growth Regulator Group, Monograph 7: 44- 50, Wunsche, U. 1977. Influence of growth retarding sub- stances on cereals. 3. Field experiments with CCC, DPM and CEPA on wheat, rye, barley and oats. Zeitschrift fur Acker- und Pflanzenbau 145: 238-253. 442 AGRICULTURAL SCIENCE IN FINLAND Vol. 4: 429-443. SELOSTUS Kasvunsääteiden käyttökelpoisuus ohralla Leila-Riitta Erviö, Heikki Jalli, Markku Kontturi, Heikki Hakkola, Arjo Kangas ja Paavo Simojoki Maatalouden tutkimuskeskus Kasvunsääteiden vaikutusta ohran laon estämiseen ja sadonmuodostukseen erilaisissa kasvuoloissa tutkit- tiin vuosina 1985-89 kuudella koepaikalla Maatalou- den tutkimuskeskuksessa. Tutkitut kasvunsääteet oli- vat klormekvatti ja etefoni yksinään sekä seoksina keskenään tai mepikvatin kanssa. Niillä käsiteltiin heikkokortiset Arra- ja Kilta-lajikkeet kolmena eri ajankohtana. Vuosina 1988-89 tutkimukseen sisältyi myös kaksi typpilannoitustasoa. Viljan lakoontuminen vaihteli koekohtaisesti, ei- vätkä esiintyneet erot olleet yksiselitteisesti sidoksis- sa koepaikan maantieteelliseen sijaintiin tai tutkimus- vuoteen. Tutkimus osoitti, että kalliita kasvunsääteitä ei kannata käyttää rehuohrassa, ellei huomattavaa lako- riskiä ole olemassa. Lakoriskin muodostumiselle tär- keimpiä tekijöitä olivat tehoisa lämpötilasumma ja sademäärä ohran kylvön ja pensomisen alkuvaiheen (Feekes 2) välisenä aikana. Nämä tekijät selittivät 64 % Arran ja 68 % Killan lakoontumisesta. Niiden perusteella arvioitu lakoontuminen toteutui tässä tut- kimuksessa ennusteen puitteissa. Tutkituista kasvunsääteistä etefoni ja mepikvat- ti/etefoni lyhensivät kortta ja ehkäisivät lakoontumis- ta tehokkaimmin, mutta eivät estäneet lakoa riittävästi epäedullisimmissa kasvuoloissa. Näiden valmisteiden käyttö ohran lippulehtiasteella lisäsi satoa ja voimak- kaan lakoontumisen esiintyessä säilytti hehtolitrapai- non kauppakelpoisuusrajan yläpuolella. Ohran sadonmuodostusta sääteleviin tekijöihin kasvunsäädekäsittelyjen vaikutus jäi vähäiseksi. Var- hainen klormekvattikäsittely ei lisännyt ohran versou- tuvuutta. Paikalliset kasvuolot ja laon esiintyminen osoit- tautuivat tärkeimmiksi tekijöiksi kasvunsäädekäsitte- lyjen kannattavuudelle. Ellei lakoa esiintynyt, käsit- telyt eivät tuottaneet taloudellista hyötyä tai olivat suorastaan tappiollisia. Epäedullisissa kasvuoloissa, joissa lakoontuminen oli voimakasta, erityisesti ete- fonia sisältävät valmisteet auttoivat taloudellisen tu- loksen saavuttamisessa. Niiden käyttö ohran lippuleh- tiasteella tuotti voittoa, joka vaihteli 70-390 mk/ha käsittelyjen mukaan. 443 AGRICULTURAL SCIENCE IN FINLAND