JOURNAL OF THE SCIENTIFIC AGRICULTURAL SOCIETY OF FINLAND 197 Maataloustieteellinen A ikakauskirja Vol. 51: 197-209. 1979 Adaptation of silage maize varieties under extreme northern growing condions in Finland Seppo Pulli University of Helsinki, Dept, of Plant Husbandry, 00710 Helsinki 71 P. M. A. Tigerstedt University of Helsinki, Dept, of Plant Breeding, 00710 Helsinki 71 Osmo Kara University of Helsinki, Dept, of Farm Engineering, 00710 Helsinki 71 G. Bruninghaus Wiurila, 24910 Halikko Abstract. Trials with maize varieties from various places in the world were started in 1975. In preliminary trials in 1975, 280 varieties were tested. Between 19 and 23 varieties were selected for ordinary variety tests in 1976 —7B at the University farm in Siuntio. Weather conditions, particularly average daily temperatures in 1975 were better than the long term averages, and in 1976 —7B far below the average growing conditions. Dry matter yields of the seven harvested silage varieties in 1975 varied between 5.8 and 11.5 tons/ha. In 1976 —7B the variation in DM yields was 3.8 —B.O tons/ha among 19—23 varieties. In 1975, 44 varieties out of 280 produced mature seed. Only one variety matured in 1978, but none in 1976 77. The developmental stage of silage maize is primarily determined by ear percentage and secondarily by DM %. In 1975 the average ear % of seven varieties was 49.1 %, in 1978 18.1 % and in 1976 —77 only 4.0—5.7 % in DM. As a result of the variety tests promising varieties from Yugoslavia, France and Germany could be found. It can be concluded from the long term temperature data that with very early hybrid varieties a mature grain yield can be harvested twice in ten years. Good quality silage material can be harvested six times in ten years and a sat- isfactory crop can be obtained eight times in then years. The limiting factor for the growth and development of maize in Finland is the low average temperature of the growing season. Important but less significant is the length of the vegetative period, which is determined by the first killing frost in the fall. The temperature deficit is particularly critical at the beginning of the growing season. Introduction The adaptability of maize varieties to Finnish climatic conditions was first studied in the 1930’5. The most important results were published by A. I. Virtanen. According to Virtanen the fresh weight of the best maize variety https://www.c-info.fi/en/info/?token=1rTLx0a2yXrZEwOv.QEphbaPcB9uBmqlvTN3eUA.0FeSzYHbgjboTcWaKP5LVEUPKsVYW3WC0P1Ae5Nfe7yGHELvPmINI93e7NT38NzzZeNDx61KDhQzT8bl9mADed578k2Fa1RMkdGpSAP-EvAOMgBufHz8XR7IhuNOOroBvfaaRSLS5_AEAfegR6lB5i1z7GUDhBzL5ndLEqtCw0mUbIEG4hjj7QCowi7znBba1Ap7lnlGxPRy2DevP068keCTrYFMiohDKw 198 varied between 64 lO7 tons/ha, the average yield being 72.5 tons/ha (Vir- tanen 1938). At this time silage maize was widely cultivated on private farms. Virtanen’s data, obtained from 131 farms in 1937, summarizes the average fresh yield of maize at 41 tons/ha (Virtanen 1938). At the Plant Breeding Institute of Hankkija in Tammisto maize varieties have been studied since the early 1930’5. In 1953—54 the fresh yield of silage maize varieties varied between 36—80 tons/ha. The average fresh weight of varieties was 54 tons/ha. The dry matter percentage (DM %) was about 11.7—13.6 and the harvested yield about 7.5 tons DM/ha. In 1955 in Tammisto maize suffered from drought and the fresh yields reached only a level of 9—22 tons/ha. In 1957—5B in Tammisto the yields were between 46—83 tons/ha (Ravantti 1956, 1960). In later research program the average dry matter yields of silage maize varieties varied between 5.4—6.8 tons/ha in 1965—69 and between 5.3—10.6 tons/ha in 1973—74 (Raininko 1970, Juuti and Raininko 1975). At the Agricultural Research Center in Tikkurila maize trials were carried out already in the 1930’s but were interrupted during the war. In 1950 they were resumed in connection with the FAO hybrid maize program. These trials were mainly carried out by the Dept, of Plant Husbandry in Tikkurila and three experimental stations in southern Finland. Yields varied widely in various years and were generally low (Yllö 1962). In 1937 the variety tests showed a yield variation of 17.7—54.1 tons/ha the average yield of all varieties being 31.2 tons/ha. In 1950, 1952 53, 1956 and 1958 the trials failed more or less completely mainly because of cool growing seasons, early autumn frosts and the use of largely nonadapted varieties. Maize variety trials in the 1950’s and in the early 1960’s showed that maize was an uncertain field crop under Finnish conditions. However, it was con- cluded that it can be grown with certain limitations in South Finland, prin- cipally on fertile, warm soils, where there is little danger of autumn frosts (Yllö 1962). As a result of favorable development of hybrid maize breeding in Central Europe during the last ten years, the economic northern limit of maize growing has been moved to northern Germany and Denmark. Due to this development a new start in maize research was made in 1975 in Finland. The new survey of maize production in Finland began with the testing of large collections of breeding material from all over the world. Subsequently this material has been tested under different cultivation conditions. The research was financed by the Cultural Foundation of Finland in 1975—77 and the Ford-Foundation in 1978. Materials and methods The preliminary variety tests were established on the Wiurila farm in Halikko near Salo in 1975. A collection of 280 varieties was tested in one replication. This screening nursery served the purpose of selecting promising material from a world wide collection of potential maize lines and varieties. 199 In subsequent years (1976 78) the experimental desing was a randomized block wTith 4 replications. This was carried out on the Suitia Helsinki Uni- versity farm: Screening nursery Variety trials 1975 1976 1977 1978 Varieties 280 19 20 23 Replications 1 4 4 4 Plot size m 2 16 48 26 16 Fertilization kg/ha (15 —l5 15) 1 000 1 000 1 000 1 000 Seeding date May 5 May 17 May 12 May 17 Plants/m2 10 10 10 10 Row spacing cm 80 80 80 80 Plant spacing cm 12.5 12.5 12.5 12.5 Seeding depth cm 7 7 7 7 Weed control date May 20 June 2 May 20 May 23 Irrigation mm 2 X 25 2 X 25 25 25 Harvest date Oct. 27 Oct. 6 Sept. 24 Sept. 23 A two-unit drill (Kleine Maxicorn) was used as a seeding unit. Fertilizer was applied to both sides and below the seed. The plots were pre-emergence weed-controlled with Gesaprim-50, 3—4.5 1/ha. Insects were controlled with Roxion 0.8 1/ha. The yield data consisted of the fresh weight, dry matter %, and protein content (%) in dry matter. Height measurements were taken once a week during the growing season. Weather conditions Temperature conditions during the growing seasons 1976—7B were generally below long-term averages for 1931—60 (Table 1). The year 1975 represents an above normal growing season, which resulted in a well matured high grain yield. Especially the warm and long autumn in 1975 boosted the growth and development of the maize plant. During the whole research period the precipitation stayed below the long term average (Table 1). The maize was irrigated every spring after emergence and a second time before flowering in 1975 76. During the growing seasons 1975—7B the last harmful frosts occurred during the time of May 29 June 18 (Table 1). These night frosts were harmful for the growth but did not kill the crop. The autumn frosts (—2° C) in 1976—77 stopped the growth of maize in early September. The growing seasons 1975—7B represent 170—130 growing days from the seeding date to the harvest (Table 2). Calculated degree days show the levels between 2 237° C and 1 667° C. If expressed in effective degree days for maize (t°—lo° C) the levels are between 688° C and 412° C. Calculated corn heat units (CHU) as shown by Brown (1975) 2 259° C and 1625° C do not differ very much from the degree days. 200 Table 1. Weather conditions in the experimental area in 1975 78. Years Avg.Period 1975 1976 1977 1978 1930-60 Avg. daily temperature °C May 1- 30 11.6 10.2 9.4 9.3 9.0 May 30 - June 29 12.9 12.6 13.8 14.2 14.2 June 30 - July 29 17.0 15.0 14.3 14.5 16.8 July 30 - Aug. 28 16.7 13.5 13.8 13.6 14.9 Aug. 29 - Sept. 27 13.6 8.7 8.2 8.8 9.9 Avg. 14.4 12.0 11.9 12.1 13.0 Precipitation mm May 1- 30 40 14 16 6 39 May 31 - June 29 29 51 40 52 46 June 30 - July 29 38 40 94 70 73 July 30 - Aug. 28 40 58 58 82 75 Aug. 29 - Sept. 27 60 68 64 75 65 Total 207 231 272 285 298 Killing frost Spring o.o° C 3/6 10/6 2/6 18/6 (last) -2.0° C 30/5 29/5 1/6 18/6 Autumn o.o° C 9/10 22/8 19/8 14/8 (first) -2.0° C 10/10 8/9 9/9 21/9 Table 2. Growing days, degree days (DD), effective degree days (EDD) and corn heat units (CHU) of growing seasons 1975 —7B in southern Finland. Year 1975 1976 1977 1978 Avg. Growing days 170 143 136 130 145 Degree days (DD) °C 2 237 1 667 1 679 1 714 1 824 Effective degree days (EDD) °C 688 412 433 455 497 Com heat units (CHU) °C 2 259 1 656 1 625 1 699 1 810 DD =Z (Avg daily °C) EDD = Z (Avg daily °C -10 °C) CHU = 2 (Daily Y max + daily Y min) 1) 2 h Y max = 3.33 (T max 10) 0.084 (T max 10)2 Y min = 1.8 (T min 4.44) Results and discussion Yields Under temperature conditions above average, as in 1975, 44 of the studied 280 varieties produced a matured grain. The seven best varieties showed approximate yield levels of 5.8—11.5 tons total dry matter (DM)/ha (Table 3). Total protein yields varied between 580 and 940 kg/ha. The grain yields of the seven varieties varied between 3 279 kg/ha and 5 578 kg/ha. The total DM yields obtained in 1975 in Wiurila are similar to the Danishr esults (Peder- sen 1975). Table 3. Total yields, matured seed yields and dry matter content, protein content in DM and the amount ot cars in the total yield in 1975 in southern Finland. Total yield tons/ha Matured Content % Variety Fresh DM Prot. Grain kg/ha DM! Prot. Ears LG 11 44.9 11.4 .86 5 578 25.5 7.6 53,6 LG 5 41.9 11.5 .83 5 550 27.4 7.3 52.5 LG 672508 39.5 11.0 .94 4 955 28.0 8.6 43.1 LG 775007 38.0 10.0 .89 4 828 26.4 8.9 46.0 LG 7 37.5 10.2 .76 4 659 27.2 7.5 50.2 CP 170 37.2 8.7 .76 3 930 23.3 8.8 Flash 22.0 5.8 .58 3 279 26.3 10.0 Avg. 37.3 9.8 .80 4 683 26.3 8.4 49.1 In 1976 under clearly unfavorable growing conditions the average total fresh and DM yields of 19 varieties were 34 tons/ha and 5.7 tons/ha (Table 4). The variation in fresh yields of all varieties was 23.8—44.8 tons/ha and in dry matter yields 3.9—7.4 tons/ha. Protein yields of all varieties averaged 630 kg/ha. Table 4. Fresh weight, dry matter (DM) and protein yields and DM, protein and ear content {%) of silage corn varieties in southern Finland in 1976. Yields tons/ha Content % Variety Fresh wt DM Prot. DM Prot. Ears LG 11 44.8“ 7.4“ HIT 40.3»“ 6.9»“ Hansa 39.1»“ 6.7»“ LG 9 38.2»“ 6.6»“ LG 7 38.3»“ 6.3»“ Rubis 9 35.8» 6.2»“ Prior 40.2»“ 6.1»“ CP 170 33.3 » 6.0»“ LG 5 33.8» 5.8»“ ACG 200 36.9»“ 5.8» Zelder 75-102 33.6» 5.6» Flash 34.3» 5.6» EDO 30.6“» 5.4“» Velox 33.4» 5.3“» ACG 188 32.5» 5.0“» Jacques Cartieur 27.5“» 4.7“» Zelder 75-104 25.9“» 4.4“» ETA-IPHO 182 23.2“ 4.2ab Zelder 75-103 23.8a 3.9 a .81“ .75»“ .75»“ .74»“ .68»“ .64»“ .69»“ .68»“ .66»“ .65»“ .62» .61“» .64»° .56“» .60“» .54“» .44“ .48“» 49 ab 16.6“» 10.94.0 17.1“» 10.97.0 17.0“» 11.38.7 17.4“» 11.23.0 16.3“» 10.86.7 17.6“» 10.33.6 15.2“ 11.42.1 18,0» 11.43.3 17.2“» 11.42.6 15.7“» 11.33.2 17.0“» 11.07.6 16.4“» 10.96.0 17.4“» 11.98.8 15.9“» 10.63.8 15.6“» 12.03.2 17.4“» 11.54.2 17.0ab 9.92.4 18.6» 11.32.9 16.4“» 12.66.1 Avg. 34.0 5.7 .63 16.8 11.24.8 LSD .05 8.41.6 .17 2.5 201 202 The fresh yields, dry matter yields and protein yields in 1977 equalled the ones obtained in 1976, although the growing conditions were even poorer than those in 1976 (Table 5). In 1978 (Table 6) the average yield of 23 va- rieties was 43.3 (35.4 50.9) tons/ha fresh yield, 6.6 (4.9—8.0) tons/ha DM yield and 430 (340—500) kg/ha protein yield. The yields of silage maize on 1976—7B equal those obtained by Andersson and Lööf (1959) in Sweden. Quality of the yield The percentage of ears of the total dry matter yield is a good indicator of the growing factors available to maize in any growing season. In a very favorable years in 1975 the percentage of ears of all varieties was 49.1 %, in 1978 18.1 % and in the very unfavorable years 1976—77 only 4.0 —5.7 %. The same trend, although not so clear, can be found in the dry matter content of the yield. The season 1975 represents a level of 23.3 % and the years 1976 78 a level of 15.1 16.8 % (Tables 3, 4, 5, 6). The protein content of all va- rieties over all years is between 4.7 % and 12.7 %. The figures equal those obtained in Sweden (Nordfelt 1959) Varieties The varieties common to yield trials of the years 1976—78 were LG 5, LG 7, LG 9, LG 11, CP 170, Rubis 9, Flash and AGG 200 from France, Edo Table 5. Fresh weight, dry matter (DM) and protein yields and DM, protein and ear content (%) of silage corn varieties in southern Finland in 1977. Yields tons/ha Content % Variety Fresh wt DM Prot. DM Prot. Ears CP 170 45.2» 6.90» .72» 15.3»» 10.54.1 Prior 46.3» 6.79» .75» 14.6»» 11.03.4 LG 9 40.2»» 6.21»» .65» 15.5»» 10.42.0 LG 7 40.7»» 6.13»» .61» 15.1»» 10.05.1 Rubis 9 36.2» 6.11»» .66» 16.9»» 10.87.1 Blizzard 41.5»» 5.94»» .69» 14,2» 11.55.5 ACG 200 41.7»» 5.94»» .65» 14,2» 11.04.8 Flash 37.2» 5.84»» .58» 15.7a» 10.06.4 LG 11 39.6»° 5.82»» .59» 14.9a» 10.23.2 Velox ■ 38.9b0 5,72»» .64» 14.7ab 11.26.1 LG 5 37.8»» 5.68»° .61» 15.1ab 10.75.0 HIT 36.0b 5.39b .61» 15.0ab 11.56.4 Hansa 28.7 ab 5.04ab ,54ab 17.5» 10.85.7 EDO 30.9ab 5.01 5b ,52ab 16.1»» 10.48.9 Nibak 30.1 ab 4.81ab .55 ab 16.0b 11.58.6 Kentala 31.4»» 4.60»» .58»» 14.7 ab 12.79.5 ACG 188 28.4a 4.35»» ,51 al> 15.1»» 11.63.6 ML 06 27.7 a 4.03a .46a 14.5a 11.48.3 ETA-Ipho 182 25.5 a 4.00a ,45 a 15.1at> 11.34.6 Jacques Cartieur 26.4» 3.77a .44a 14.4a 11.65.3 Avg. 35.55.40 .59 15.211.0 5.7 LSD .05 7.41.3 .14 1.4 203 Table 6. Fresh weight, dry mater (DM) and protein yields and DM, protein and ear content (%) °f silage corn varieties in southern Finland in 1978. Yields tons/ha Content % Variety Fresh wt DM Prot. DM Prot. Ears ACG 201 50.9»» 8.04» .38»» 15.8»» 4.7 12.9 Forla 47.4»» 7.78»» .49»» 16.4» 6.3 25.0 LG 11 47.2»» 7.51»» .50»» 15.9»» 6.7 8.4 CP 170 48.5»» 7.28»» .47»» 15.0» 6.4 16.4 ACG 185 47.6»» 7.28»» .48»» 15.6»» 6.6 16.2 LG 9 46.9»» 7.15»» .47»» 15.3»» 6.5 10.3 Rubis 9 43.5 ab 6.86»» ,38a » 15.7»» 5.6 19.3 ACG 189 45.8a» 6.77»» .47»» 14.8» 6.9 19.3 ACG 167 45.8a » 6.69»» .54» 14.6ab 8.1 19.9 Hansa 41.7a » 6.65»» ,35ab 16.8cP.95 %<_ 27/9-16/10 22/9- 9/10 16/9-10/10 30/9-13/10 V % 62.178.5 137.862.5 A satisfactory silage crop can be reached at DD 1800 with no fatal frost earlier than Sept. 20. Along the Finnish coastline (and on the Aland islands) one can expect such conditions eight times in ten years. Although we have Table 11. The distribution of growing seasons of years 1963 1978 according to the degree days into six temperature classes in four locations of southern Finland and the average degree days between May 11 Sept. 27 of sixteen years. Degree Number of years Days °C Turku Jokioinen Tikkurila Lappeenranta >2lOl 1-22 2001-2100 3 2 3 2 1901-2000 7 2 5 3 1801-1900 4 7 5 6 1701-1800 1 4 1 3 1601-1700 - 1 - - Avg. °C 1942 1845 1952 1920 no particular experience of growing maize on the Aland islands it would seem that some areas, where sugarbeets are now grown particularly well, should also be well suited for maize. Summarizing from Tables 1, 10 and 11 one may conclude that maize pro- duction in such extremely northerly areas as southern Finland is limited ba- sically due to the occurrence of fatal low temperatures during the vegetative period, which otherwise would be long enough under normal years. This temperature deficit is particularly hazardous at the beginning of the growing season. In particular, resistance to occasional low temperatures should thus, be emphasized in maize breeding programs for extremely northern locations. Fig. 1. The relationship between the crop height and cumulative temperature sum °C during the growing season expressed in degree days (DD), in effective degree days (EDD) and in corn heat units (CHU) in variety tests in 1976 78. 207 208 REFERENCES Andersson, G. & Look, G. 1959. Försöks- och förädlingsarbeten med ensilagemajs vid Sveriges Utsädesförening. Växtodling 11: 109—125. Brown, D. M. 1975. Heat units for corn in Southern Ontario. Ministry of Agriculture and Food. Factsheet N:o 75 077. 4 p. Juuri, T. & Raininko, K. 1975. Lisärehukasvit. Hankkijan Siemenjulkaisu 1975: 100 110. Nordfelt, Sam 1959. Ensilage av grönfodermajs. Växtodling 11: 65 76. Pedersen, K. E. 1975. Sorter af majs til grönhöst 1972 74. Stat. Fors. virks. Pl.kultur. Medd. 1237. 2 p. Raininko, K. 1970. Lisärehukasvit. Hankkijan Kasvinjalostuslaitos. Siemenjulkaisu 1970: 111-125. Ravantti, S. 1956. Rehumaissin viljelemisestä Ruotsissa ja Suomessa. Karjatalous: 98 99. 1960. Lisärehukasvit. Hankkijan Kasvinjalostuslaitos. Siemen julkaisu 1960: 156 175. Shawn, R. 1955. Climatic requirement. Corn and corn improvement. Agronomy. Yol. 5. ed. G. F. Sprague. 315 341. New York: Acad. Press. Inc. Wallace, H. A. & Bressman, E. N. 1937. Corn and corn growing. 431 p. John Wiley & Sons, New York. Virtanen, A. I. 1938. Kokemuksia maissin ja maissi-peluskin viljelyksestä maassamme. Karjatalous: 14: 243 253. 1940. Maissin viljelyksestä ensi kesänä. Karjatalous 8: Erip. 7 p. Äkerberg, E. & Torsselle, B. 1959. Förädlingsmetodiska undersökningar med ensilagemajs. Växtodling 11: 65-107. Yllö, L. 1962. Maissin viljelykokeista Suomessa. Maatal. ja Koetoim. 16: 101 110. Ms received May 3, 1979. Fig. 2. The relationship between the dry matter production of maize and the cumulative tem- perature sum °C expressed in degree days (DD), in effective degree days (EDD) and in corn heat units (CHU). 209 SELOSTUS Maissilajikkeiden sopeutumisesta Suomen kasvuoloihin Seppo Pulli Helsingin yliopisto, Kasvinviljelytieteen laitos, 00710 Helsinki 71 R. M. A. Tigerstedt Helsingin yliopisto, Kasvinjalostustieteen laitos, 00710 Helsinki 71 Osmo Kara Helsingin yliopisto, Maatalousteknologian laitos, 00710 Helsinki 71 G. Bruninghaus Wiurila, 24910 Halikko Maissin lajikekokeet Suomen Kulttuurirahaston tuella käynnistettiin Wiurilassa, Salossa vuonna 1975. Vuoden 1975 alustavissa kokeissa oli 280 lajiketta. Näistä 19 —23 valittiin lopullisiin lajikekokeisiin Yliopiston koetilalle Siuntioon vuosiksi 1976 78. Sääolosuhteet vuonna 1975 olivat keskimääräistä paremmat, vuosina 1976 —7B keskimääräistä huomattavasti heikommat. Kuiva-ainesadot 1975 olivat 5.8 11.5 tn/ha. Vuosina 1976—7B vaihtelut kuiva-ainesadoissa heikoimman ja parhaimman lajikkeen välillä olivat 3.8 —B.O tn/ha. Suotuisana kasvukautena 1975 kovan, kypsän siemenen tuotti 44 lajiketta. Vuonna 1976 —77 kypsää siementä ei tuotta- nut yksikään lajike, vuonna 1978 yksi lajike. Säilörehuasteisen, kellertävän tai keltaisen sie- menen tuotti vuonna 1977 kahdeksan lajiketta, vuonna 1978 yhdeksän lajiketta ja vuonna 1976 ei yhtään lajiketta. Lajikekokeissa löydettiin muutamia lupaavia hybridejä Ranskasta, Saksasta ja Jugosla- viasta. Pitkäaikaisiin lämpötilatietoihin perustuen voidaan todeta, että aikaisista hybrideistä saadaan nykyisillä lajikkeilla kasvuoloissamme kypsä jyväsato kahdesti kymmenessä vuo- dessa, hyvä säilörehusato kuudesti kymmenessä vuodessa ja tyydyttävä säilörehusato kahdek- san kertaa kymmenessä vuodessa. Maissin kasvun ja kehityksen tärkein rajoittava tekijä kasvuoloissamme on alhainen vuoro- kautinen lämpötila koko kasvukaudella. Alhaisesta keskilämpötilasta johtuen lämpötilasumma jää useasti alle 1900° C, jota on pidettävä kannattavan säilörehumaissin viljelyn alarajana. Toinen merkittävä tekijä on ensimmäisen tappavan syyshallan ajoittuminen useasti syyskuun alkupuolelle, mikä oleellisesti vähentää maissin kasvuaikaa. Kevään ja alkukesän usein al- haiset lämpötilat hidastavat maissin alkukehitystä. Tästä syystä maissilla nopean kasvun vaihe saavutetaan vasta elokuun vaihteessa, jolloin lämpöoloissa, ja varsinkin säteilymäärissä on tapahtunut merkittävä vähentyminen.