JOURNAL OF THE SCIENTIFIC AGRICULTURAL SOCIETY OF FINLAND 477 Maataloustieteellinen Aikakauskirja Vol. !2: 477-494, 1980 Growth factors and management technique in relation to the develop- mental rhythm yield formation pattern of a seeding year lucerne stand SEPPO PULLI University of Helsinki, Department of Plant Husbandry, 00710 Helsinki 71 Abstract. The investigation of seeding year lucerne stand development and yield formation pattern was carried out at the University of Helsinki in Viikki in 1973—74. The management techniques studied were the number of cuttings and the density of stand establishment. The variety used was Danish Isis-Daenfcldt. The maximum DM yield was obtained from a seeding rate of 20 kg/ha. The maximum DM yield produced under the favour- able growing conditions in 1973 was 5. 7 tons/ha and under the less favourable conditions in 1974 3.3 tons- /ha. No more than two cuts in the year of seeding are recommended. The radiation used by lucerne was 0.3 0.5 %of the total radiation reaching the surface. A 10 % decrease in radiation in 1974 resulted in a 50 % decrea- se in photosynthctic activity mainly due to differences in temperature and overabundant precipitation. The opti- mum LAI was obtained from scedingratcs 5 kg/ha. From seeding to emergence a temperature sum of 120 °C is needed and from seeding to flowering a sum of 800°C. From cutting to the next flowering a sum of 600— 700°C is needed. Three cuts provided forage 6.3 % units more digestible than two cuts. Root carbohydrate levels suggest that the last cut should not be made later than mid-August. I Introduction Lucerne is generally accepted as one of the most important forage species for domes- tic animals in those areas where it may be successfully cultivated. The actual range where lucerne is cultivated extends between 30 and 60 degrees latitude in the nor- thern and 20 and 40 degrees latitude in the southern hemisphere (SMITH 1962). Lucerne is well adapted to different temperature regimes as its wide growing area illustrates. Lucerne thrives best in an area where the growing season’s average temperature is 18—20°C. Germination begins already at 4—6°C, but its optimum temperature is 3 1—37°C. The optimum temperature for lucerne nitrogen fixing bac- teria is 1 s—3o°C (BOLTON 1962). A substantial reduction in bacteria activity is observed in temperature ranges of 10—12°C and 35—40°C because the nitrogen fi- xing capability is retarded (BOLTON 1962). After wintering the specie’s spring development begins when temperatures reach B—lo°C. Hardened lucerne can withstand freezing temperatures of up to —2 5°C on bare ground. After the hardening is lost in the spring the root meristematic area may suffer damage if the temperature falls to just ±0 °C (SMITH 1962). Young lucerne shoots are considerably more succeptible to cold spring nights than those of red clo- ver. Nevertheless, the adaptability of lucerne is best illustrated by the fact that it is successfully cultivated in areas where winter temperatures exceed —4O°C. https://www.c-info.fi/en/info/?token=6lj_1jKw0ZYiaSPT.pP1JVCrimmNYh7N6jEKHkQ.ex1welKUsvqg-h2Oboo-YCqGbCwPy4vN6-f4rTrvXef5KMgRgoKW5wQSUy6PORXiPxpcemeM_JM3g_EiVBAJ2ihptRe8Ccd98c8JVpBS5o2HnT4gST06wMAmO2bGLdbpjqug9WBI4sMfS2cdC8F4jYPohk2s6epftQ 478 In areas such as Hungary, where the average annual temperature is 11°C, five harvests of lucerne are possible. Where the average annual temperature ranges from 7.5 to 9°C, as in Germany, 3—4 harvests are common. These average annual tempe- ratures represent temperature sums of 4500—3000°C for growing seasons covering April to October (BOLTON 1962). For flowering (BECKER-DILLINGER 1929) lucerne needs a temperature sum of 850—900°C and the same amount of heat for each of the following cuts. As the average temperature sum in southern Finland is 1900—2100°C, this means that at most two lucerne harvests are obtainable during the growing season. Because of its deep growing (6—9 m) main root lucerne can withstand drought better than any other forage plant (SCHANTZ and PIEMESEL 1927). On the otherhand abundant ground and surface water are detrimental and one of the major obstacles to successful establishment of lucerne. According to SCHANTZ and PIEMESEL (1927) the evaporation coefficient for lucerne is equivalent to about 180 mm of precipitation per ton of dry matter. For areas where 2—3 cuts are made the precipitation needed ranges from 450—600 mm and in areas where more cuts are possible from 900—1200 mm. Investigations and practical cultivation have shown that 850—1000 mm of precipitation is the upper limit lucerne can tolerate without serious problems. Because of its deeprootedness lucerne requires a growing medium where the sub- soil is permeable. Lucerne is known to thrive also where the lime content of a perme- able subsoil is high (MULTAMÄKI 1965). It requires a soil where the pH is >6.5. In the plough layer lime should be present in a concentration of 12 t/ha. A lucerne harvest of 6 t/ha removes from the soil about 30 kg P/ha, 210 kg K/ha and 150 CaO/ha. At the same time it leaves 5—7 t/ha of organic matter and 300—400 kg N/ha. Lucerne obtains its nitrogen from nutrients in the soil or via its root bacteria which fixes it from the air. The nitrogen fixing capacity of lucerne is 40 and 84 % more efficient than for red clover and peas respectively. Cultivation possibilities for lucerne in Finland have been investigated by HEIKINHEIMO (195 5), TEITTINEN (195 5), RAVANTTI (195 5, I960), MULTAMÄKI (1962, 1965, 1969, 1970), BÖCKELMAN (1967), RAININKO (1970) and PULLI (1973, 1977). All have shown that in areas where lucerne thrives its yield production has surpassed that of red clover and fescue. The factors which most seriously hinder lucerne growth are the low reaction of the soil, low nut- rient content of the soil, too much groundwater, surface water, a poorly suited varie- ty, short growing season, low temperatures and various factors resulting in poor wintering. The purpose of this study was to determine the relationship between growth and growth factors in the early development of lucerne, in respect to the intraspecific compentition and other cultivation intensities. The study was conducted during 1973-74. 2. Materials and methods 2.1. Field arrangements The field trials were established on the University Farm in Viikki in 1973. The plots were organized in the following ways; 479 1973 1974 Experiment] design: Split-plot Main plot Cutting treatments 1. 2-cut 1. 1-cut 2. 3-cut 2. 2-cut Sub-plot Seeding rates 1 kg/ha (40 seeds/m 2 ) 5 " (200 " ) 10 " (400 " ) 20 " (800 " ) 40 " (1600 " ) Replications: 4 The plots were established on May 22 in 1973 and May 14 in 1974. The soil type was fine sand. The lucerne variety was Danish Isis-Dacnfeldt and the seed was inocculatcd prior to seeding. Fertilization and plant production: The experimental field was fertilized with NPK at a rate of 1000 kg/ha (2-17-15). The herbicide Dinoseb was used for weed control at 4.5 1/ha. The plots were irrigated 4 x 30 min in 1973. Cutting and yield procedure: 1973 1974 1-cut system; 6.8 2-cut system: Ist cut 24.7 17.7 2nd cut 1 8.9 2 5.9 3-cut system; Ist cut 9.7 2nd cut 9.8 3 th cut 4.10 Crop growth and yield analyses: For dry matter determinations two 200 samples of chopped forage material per plot were taken and dried for 24 h at 100°C. The 200 g samples intended for in vitro digestibility tests were dried for 24 h at 70°C. The emergence measurements were carried out June 6 in both years. Leaf area index (LAI) measurements were conducted weekly throughout the entire growing season in both tcst years. The LAI sample size per plot was 0.045 m 2. The overall height of the crop was measured daily in 1973. and twice weekly in 1974. The root samples for carbohydrate analysis and forage for in vitro digcstibili- ty tests were collected once a week throughout the entire growing season. Stand density and root yields were measured on Nov. 5 in 1973 and Nov. 21 in 1974. Metcorologic data was obtained from the weather station at nearby Seutula airport. 2.2. Laboratory analyses Leaf area was measured with an optical leaf planimeter (Model Kl) designed and built by the Technical University of Helsinki. Forage in vitro degestibility was determined according to the procedure of TILLEY and TERRY (1963). The reducing sugars of lucerne roots were measured with the calorimetric methods of NELSON (1944) and SOMOGYE (19 52) as applied by SMITH (1969). The dry matter energy content of forage was determined with a PHILLIPSON oxygen microbomb calorimeter according to PHILLIPSON’S (1964) procedure. 480 3. Weather conditions The weather conditions of the 1973 and 1974 growing seasons differed consi- derably from each other. Summer 1973 was warm and dry while summer 1974 was chilly and rainy (Tables 1,2, 3). When comparing the temperature conditions in degree days (Table 4), the temperature sum of the 1974 growing season on Aug. 8 was one month late compared to that of 1973. Also radiation conditions were more favourable in 1973 than in 1974. Because of the weather conditions prevailing in 1973 several irrigation treatments were needed in order to meet the plant’s water re- quirements. 4. Results and discussion 4.1. Yields and stand characteristics Yields The seeding-year yields (Table 5) during the favourable 1973 growing season va- ried in the 2-cut system at different seeding rates from 1.1 —5.7 tons DM/ha and in the 3-cut system between 1.0 and 5.7 tons DM/ha. In 1974, which was a less fa- vourable season for lucerne, the 1-cut system yielded 1.2 tons DM/ha and the 2-cut system 3.3 tons DM/ha. The yields of 5.7 and 3.3 tons DM/ha represent 70 and 30 % respectively of the average lucerne yield level in Finland (MULTAMÄKI 1969). According to TESAR and JACKOBS (1972), in the northern United States seeding-year lucerne yields average 4—5.8 tons DM/ha and represent 40—60 % of the yields from older stands. Under unfavourable conditions the seeding-year yield may be even less. Of the seeding rates tested 20 kg/ha proved to be sufficient to obtain the maxi- mum yield (Fig. 1,2). These results represent a 5 10 kg less performance level than MULTAMÄKI’s (1965) results but considerably higher seeding-year results than those reported by BOLTON (1962), TESAR (1972) and PULLI (1973) in the United States. The tests showed that an above normal seeding rate did not increase the yield significantly but because of the increased interplant competition the roots remained smaller and wintering ability weakened. It was also found that in sparse stands the competition between lucerne and weeds reduced lucerne’s growth vigor particularly when a low cutting frequency was used. On the basis of this finding two cuts is the optimum cutting frequency under favourable growing conditions. Stand characteristics: In both of the growing seasons (Table 6) lucerne required a temperature sum of about 120°C from seeding to emergence. The average temperature sum needed from seeding to flowering was 860°C. The sum required from the first cutting to flowe- ring and the second cutting to flowering was about 610—650°C. These require- Table 1. Average monthly temperatures and the deviation from the long term average in 1973 and 1974 in Helsinki. 1973 1974 Month Avg. Deviation Avg. Deviation temp.°C from avg, temp.°C from avg. May 9.9 +0.6 7.6 -1,7 June 16,8 +2.3 14.7 +0.2 July 20,2 +2.4 16.2 -1.6 Aug 15.6 -0.9 14.9 -1.9 Sept 8.4 -3.3 13.3 +1.6 Table 2. Number of rainy days (prcc 1 mm) and amount of precipitation (mm) and deviation of precipita- tion from long term average in Helsinki in 1973 and 1974. 1973 1974 Rainy Free. Dev.Month Rainy Free. Dev. days mm days mmmm May 7 34 - 3 6 34 - 3 June 4 22 -25 8 48 + 1 July 5 24 -38 14 52 -10 Aug 7 33 -33 12 49 -17 Sept 14 117 +5l 17 145 +79 Z 37 2 30 57 328 Table 3. Relative humidity (%) and solar radiation cal/cm2 in Helsinki in 1973 and 1974. Avg. Solar radiation cal/cm 2Month rel. hum. % 1973 1974 1973 1974 May 71 63 June 6 5 68 July 66 78 Aug 74 82 Sept 80 84 13690 16973 16903 11691 4825 14176 1 5267 11613 11334 5678 Avg 71 75 64082 58068 Table 4. The temperature seen in degree days and deviation from the long term average during growing seasons 1973-74. 1973 Date 1974 E 5°C Dev. E 5°C Dcv. 11l + 11 25/5 65 - 35 271 + 60 9/6 147 - 65 351 + 45 19/6 257 - 49 594 +125 4/7 415 - 55 834 +192 19/7 584 - 58 962 +205 29/7 682 - 76 1092 +224 8/8 762 -107 1216 +243 18/8 861 -112 1277 +207 28/8 955 -111 1336 +l9l 7/9 1062 - 82 1350 +147 17/9 1122 - 82 1359 +ll4 27/9 1184 - 60 1391 +llB 7/10 1237 - 35 481 Table 5. Dry matter yields of seeding year lucerne stand at different seeding densities and cutting schedules in 1973-74. Seeding rates Cuts tons/ha kg/ha Cut I Cut 2 Cut 3 Total 1974 1 -cut system 1 0.09 a 0.09 a 5 0.47 ab 0.47 ab 10 0.80 b 0.80 b 20 1.07 b 1.07 b 40 1.22 b 1.22 b Avg 0.73 0.73 A 2-cut system 1 0.06 a 1.23 1,29 aa 5 0,14 a 2,32 b 2.46 b 10 0.29 ab 2.58 be 2.87 e 20 0.28 ab 2.82 be 3.10 cd 40 0.36 b 2.95 3.31 dc Avg 0.23 2.38 2.61 B LSD qj— Level 1973 2-cut system 1 0.44 a 0.67 1.11 aa 5 1.26 a 2.28 b 3.54 b 10 1.63 ab 2.63 be 4.26 b 20 2.16 b 2.89 be 5.05 be 40 2.49 b 3.21 c 5.70 c Avg 1.60 2.34 3.93 A 3-cut system 1 0.12 a 0.34 a 0.50 a 0,96 a 5 0.47 a 1.14 b 1.68 b 3.29 b 10 0.88 ab 1.43 b 1,67 b 3,98 b 20 1.23 b 2.28 c 2,09 c 5.60 c 40 1.44 b 2.22 c 2.03 be 5.69 c Avg 0.83 1.48 1.59 3.90 A LSD 05— l^vcl Table 6. Time and temperature requirements of lucerne stand in the seeding year growth and development in 1973-74. Growth stage Growing days Avg. daily temp.0 1973 1974 Temp. O°C 1973 19741973 1974 Sceding-cncrgencc 8 13 14.9 9.1 120 118 Sceding-flowering 47 66 17.7 13.4 839 883 1 st cut-flowering 28 50 21.1 14.0 592 702 2 -cut-flowering 59 10.4 610 482 483 ments were somewhat less than those reported by BECKER-DILLINGER (1929), first in regard to variety development and second as to whether the basis for obser- vation is the onset of flowering or full flowering. The population development of lucerne was studied very closely in 1973. Ac- cording to the results of BROWN and STAFFORD (1970) the seedling development could be considered excellent. Thinning of the stand which occurred by the autumn of the seeding-year was gre- atest at high seeding rates as shown earlier by PULLI (1973). The substantial thinning which occurred at the lowest seeding rate (1 kg/ha) was due to the severe competition with weeds in the spring. The shooting of the stand (Table 7) at different seeding densities was clearly si- milar to results obtained in earlier studies, for example CLEMENTS et al. (1929) and COWETT and SPRAGUE (1962). Shoot formation on an individual basis was 3.9 9.3, depending on the seeding rate and cutting frequency. Fig. 1. Seeding year yields DM tons/ha in 1973 with different seeding rates cut two and three times during the first growing season Fig. 2 Seeding year yields, DM tons/ha in 1974 with different seeding rates cut once and two times during the first growing season 484 Table 7. Population density development during the seeding year 1973 and number of shoots per plant in the autumn of the seeding year under different management practices. Seeding % from seeding density Number of shoots in the autumn rate kg/ha Emergence Autumn Ist year 2-cut 3-cut Avg. 1 80 65 9.3 8.2 8.7 5 78 88 6.8 5.8 6.3 10 74 80 5.7 4.7 5.2 20 73 64 6.6 5.2 5.9 40 67 49 5.4 3.9 4.7 Avg 74 69 6.8 5.6 6.2 The primary development of the yield was strongest at the high seeding rates and weakest in the sparse stands, despite the fact that shooting increased at the same time, as also DAVIDSON and DONALD (1958) have shown. No LAI differences (Fig. 4) were observed in the final autumn cuttings of stands having seed amounts of 5 kg/ha or more and the yield differences were minor (Table 5). This supports PULLI’s observations (1973) in the USA. 4.2. Photosynthetic efficiency Lucerne used an average of 0.5 % and 0.3 % of the total radiation in 1973 and 1974 respectively for yield formation (Fig. 3). There were few differences between the cutting systems. The energy value of the yield ranged from 3.9—4.7 keal/g in in- dividual cuts at different seeding rates (Table 8), but differed very little for complete cutting systems. These results were very similar to those PULLI (1980) obtained with a mixed clover-grass stand. The total radiation for 1974 was about 10 % less than in 1973 (Table 3), whe- reas stand radiation utilization in 1974 was almost 50 % less than in 1973 (Fig. 3). This is an indication that at Finnish latitudes radiation is not a limiting factor for lu- cerne photosynthesis, but that temperature and excess precipitation are, as CHANG (1968) reported. The measured photosynthetic efficiencies were representative of those that NODDACK and KOMOR (1937), MAXIMOV (1938), RABINOWITCH (1945), WASSINK (1948), KAMEL (1959) and PULLI (1980) have found for other different plants. 4.3. LAI and Plant Height Relationships Yields and LAI The large temperature differences between 1973 and 1974 resulted in noticea- bly slower lucerne development in 1974. September of 1974, however, was excepti- onally warm. The largest LAI value measured in 1973 was 4.3 and in 1974 5.2 485 (Fig. 4,5). At high seeding amounts maximum LAI was reached faster than in hin- ner stands. This tendency weakened with the arrival of autumn and in the last au- tumn cut at the end of the growing season all stands with seeding rates > 5 kg/ha had developed nearly equal LAIs. This phenomenon was even more pronounced the more often the stands were cut (Fig. 4). The dry matter yields developed in very much the same way as LAI. This result differed from that of FUESS and TESAR (1968) where LAI reached its peak rather quickly after which the old leaves drop- ped off but the dry matter yield still increased. In Viikki lucerne’s growth potential was obviously less and its growth rhythm slower and the maximum LAI values were Fig. 3. Photosynthctic efficiency of a lucerne stand with different seeding rates cut 1—3 times in 1973—74 486 Table 8. Energy-value of lucerne stand keal/g DM in invidual cuts at different seeding rates in 1973—74. Seeding rate Cuts keal/g DM kg/ha Cut I Cut 2 Cut 3 Avg. 1974 1-cut system 1 4.504 4.504 5 4.511 4.511 10 4.447 4.447 20 4.380 4.380 40 4.417 4.417 Avg 4.451 4.451 2-cut system 1 4.616 4.481 4.549 5 4.288 4.564 4.426 10 4.437 4.594 4.516 20 4.452 4.376 4.414 40 4.181 4.638 4.410 Avg 4.395 4.531 4.463 1973 2-cut system 1 4.345 4.733 4.539 5 4.363 4.624 4.494 10 3.904 4.573 4.239 20 4.588 4.611 4.600 40 4.349a.522 4.436 Avg 4.310 4.613 4.462 3-cut system j 1 4.663 4.567 4.726 4.652 5 4.731 4.674 4.802 4.736 10 4.604 4.579 4.705 4.629 20 4.662 4.577 4.576 4.605 40 4.626 4.743 4.776 4.715 Avg. 4.657 4,628 4.717 4.667 not reached. According the FUESS andTESAR (1968) the maximum LAI for lucerne is 5—6. In all cuts of the different cutting systems for both 1973 and 1974 the fol- lowing linear relationship was obtained between dry matter yield (x) and LAI (y): Y = 0.57 + 1.26 X (r = .915 XXX) Plant height relationships: The daily increase in plant height (Fig. 6), average temperature and the radia- tion amount followed each other well. Temperature alone accounted for 70—7 5 % of the increase as the following indicate; x = avg. daily temp (°C), y = daily height increment (cm): 5 Fig. 4. Seeding year LAI development and yields tons/ha DM in individual cuts with different seeding rates in 1973 Fig. 5. Seeding year LAI development and yields tons/ha DM in individual cuts with different seeding rates 488 Spring growth: y = —1.33 + 0.135 x (r = .85xxx ) Summer growth: y - —4.43 + 0.331 x (r = .S? 10™) Autumn growth: y = —1.47 + 0.197 x (r = ,84 xxx) These results agree with those of HARI and LEIKOLA (1974). Fig. 6. Average daily temperatures and radiation and lucerne stand height increments during the seeding year development in 1973 According to the calculated linear relationships the border temperatures for spring, summer and autumn growth are + 10°C, +l3°C and +B°C respectively. Of these the summer temperature value can be questioned. The high activation value most likely is a result of the abundant irrigation and relatively high daily temperatu- res in 1973. Strong midsummer height growth can also be seen in Table 9. Under favourable conditions height growth in the 2-cut system is steady throughout the en- tire growing season. From Fig. 7 it can be seen that temperature exerted a strong influence into the autumn despite the fact that illumination had somewhat weakened. These results support those reported by PULLI (1980) for meadow fescue and a mixed clover- grass stand. Tabic 9. Daily height increment (cm/day) in different cutting systems during the time 12.6—31.8 in 1973—74. Cutting 1973 1974 periods 2-cut 3-cut 1-cut 2-cut I 1.26 1.26 1.13 0.93 II 1.24 1.59 1.10 111 0.90 Avg 1.25 1.25 1.13 1.02 Avg. cuts 1.25 1.08 Fig, 7. Temperature sum in degree days ( O°C) and radiation sum (cal/cm 2/min) development compared to the height development of a seeding-year lucerne stand cut two and three times in 1973 489 4.4. Stand quality development As part of this investigation the in vitro digestibility of lucerne was monitored weekly during the period 25.6.—4.10. The reduction in digestibility occurred even- ly in the 2-cut system (Table 10), being less than 0.5 % in each cut. In the 3-cut sys- tem as the development progressed toward the autumn so too did the rate of change in digestibility, as the values of 0.20, 0.30 and 0.75 % for 1973 indicate. These di- gestibility changes agree with those observed by REID et al. (1959) and PULLI (1973) for lucerne and by countless others in studies of forage, for example HUOKUNA (1973), RAININKO (1973), SYRJÄLÄ et al. (1978). The large changes in digestibility during the early autumn were influenced by the strong growth poten- tial of the stand combined with the favourable growing conditions. The 3-cut system produced fodder about 6.3% units more digestible than the 2- cut system (Table 11). Because the final cut of the 3-cut system was made on Oct. 4, abundant shoot development in September increased the digestibility of this final cut significantly. At the same time there was a loss of terminal shoot dominance. 4J. Carbohydrate reserves in lucerne roots GRANFIELD (1935) found that a substantial reserve nutrient level is a prerequisite for the successful wintering of lucerne in northern cultivation areas. In lucerne the carbohydrates available for growth should be about 35 % of the dry weight of the roots in order to assure satisfactory wintering (SMITH 1962). Carbohydrate reserves vary with the cuttings (GRABER et al. 1927) and too many cuttings during the growing season may result in a too low reserve nutrient level in the autumn and winter (SMITH 1962). In the lucerne study at Viikki the reserve nutrient level of lucerne roots dropped by about 10 % of the total dry matter content following cutting (Fig- 8) in the fa- vourable 1973 season, but then rose to a level exceeding 30 %. The rate of increase was slower in the 3-cut system than the 2-cut system. During the rainy and cool gro- wing season of 1974 carbohydrate reserves were not used much for yield formation Table 10. Changes in in vitro digestibility of lucerne stand % per day when cut two or three times during the growing season. Cutting Changes in in vitro digestibility % per day system 25/6-9/7 25/6-23/7 23/7-10/8 6/8-3/9 20/8-3/9 2-cut -0.45 -0.48 3-cut -0.21 -0.30 -0.75 Table 11. Invitro digestibility (%) of lucerne stand in 1973 cut two and three times during the growing season. Cutting system Cuttings Cut 1 Cut 2 Cut 3 Avg. 2-cut 62,1 68.8 65.4 3-cut 71.4 67.3 74.7 71.7 490 491 and as a result the reserve level remained high throughout the entire growing season (Fig. 9). The carbohydrate level in lucerne roots in the Viikki test should have ensu- red good wintering. As satisfactory wintering did not occur the reasons are many. Good wintering always requires favourable growing conditions. In addition, ma- king the last cut at the latest by mid-August appears to assure good wintering of lu- cerne. Having the last cut in mid-August means making only two cuts during the growing season. Fig. 8. Root carbohydrate levels of a lucerne stand cut two and three times during the seeding year 1973 Fig. 9. Root carbohydrate levels of a lucerne stand cut once and two times during the seeding year 1974 492 5. Summary and conclusions At the university farm in Viikki a test series was conducted during 1973—74 on the growth and development of lucerne during the seeding-ycar. The variety used was the Danish Isis-Daenfeldt lucerne. On the basis of the results the following con- elusions can be made: 1.) The maximum dry matter yield was obtained from a seeding rate of 20 kg/ha. By the autumn of the seeding year the stand density was 60 % of the seeding density. 2.) For good wintering lucerne may be cut at most twice during the growing sea- son. The last cut should be made by mid-August in order that 4 weeks of growth following the cut may be reached before the first frost. 3.) The radiation used by lucerne was 0.3—0.5 %of the total radiation reaching the surface. Differences in the utilization amounts of radiation are due to temperatu- re differences. 4.) In both study years the optimum LAI was obtained from seeding rates > 5 kg- /ha. The greatest measured LAI values were 4.3 and 5.2 in 1973 and 1974 respectively. LAI and the yield as well as LAI and height growth were closely correlated to each other. 5.) From seeding to emergence a temperature sum of 120°C is needed, and from seeding to flowering a sum of 800°C. From cutting to the next flowering a sum of 600—700°C is needed. 6.) Three cuts provided forage 6.3 % units more digestible than two cuts. 7.) Satisfactory wintering of lucerne requires high reserves of carbohydrates in the roots as well as good root development. References BECKER-DILLINGER, J. 1929. Hulscnfruchtcnbau und Futterbau. Handbuch des gesamten Pflanzcnbaus 111. 670 p. Berlin. BOLTON, J.L. 1962. Alfalfa. Botany, Cultivation and Utilization. World Crops Book. 474 p. New York. BROWN, C.S. & STAFFORD, R.F. 1970. Get top yields from alfalfa sccdings. Better crops with Plant Food 54(1): 16—18. BÖCKELMAN, P-O. 1967. Sinimailaskokcct Ahvenanmaalla 1952—66. Maatal. ja Koctoim. 21:71—75 CHANG, J. 1968. Climate and agriculture. An ecological survey. 304 p. Aldinc Chicago. CLEMENTS, F.E., WEAWER, J.F. & HAWSON, H. 1929. Plant competition. Carnagic Inst, of Was- hington, Pubi. 398. COWETT. R.R. & SPRAGUE, M.A. 1962. Factors affecting tillering in alfalfa. Agron. J. 54: 294-297. DAVIDSON, J.L. & DONALD, C.M. 195 8. The growth ofswards of subterranean clover with particular re- ference to leaf area. Austr. J. Agric. Res. 9: 53—72. FUESS, F. & M.B. TESAR. 1968. Photosynthetic efficiency, yields and leaf loss in alfalfa. Crop Sei. 8: 159 163. GRABER, L.F., NELSON, N T., LUEKEL, W.A. & ALBERT, W.B. 1927.Organic Food Reserves in Re- lation to the Growth of Alfalfa and Other Perennial Hcrbacous Plants. Wis. Agr. Exp. Sta. Res. Bull. 80. GRANFIELD, C.O. 1935. The Trend of Organic Food Reserves as Affected by Cutting Practises. J. Agr. Res. 50: 697-709. 493 HEIKINHEIMO, A. 195 5. Sinimailasen ja puna-apilan vertailua. Hankkijan Kasvinjalostuslaitos. Sicmenjul- kaisu 1955: 1 51-179. HUOKUNA, E. 1973. Valkuaisen tuotanto nurmilla. 1. Viljelytutkimukset. Koetoim. ja Käyt. 30: 12. KAMEL, M S. 1959. A physiological study of shading and density effects on the growth and efficiency of so- lar energy conversation in some field crops. Medel. Landbouwhogesch. Wagcningcn 59: 1 101, MAXIMOV, N. 1938. Plant physiology. 473 p. (Ed. R. Harvey and Murneek). Mc Gaw-Hill Brok Co. New York. MULTAMÄKI, K. 1962. Sinimailasen lajikekoe Jokioisissa. Koetoim. ja Käyt. 19, 1: 1. 1965. Sinimailasen viljelystä. Koetoim. ja Käyt. 22, I—2: 1. 1969. Sinimailasen sadosta ja sadon laadusta Suomessa. Ann. Agr. Fcnn. Voi. 8: 205—207. 1970. Hivenaineet ja sinimailasen viljely. Sason Uutiset 12, 4: 10—11. NELSON, N. 1944. A photometric Adaptation of the Somogyi Method for Determination of Glucose. J. Biol. Chem. 1 53: 375-379. NODDACK, W. & KOMOR, J. 1937. Über die Ausniitzung des Sonnenlichtes beim Wachstum der griinen Pflanzcn untcr natiirlichen Bcdingungen. Angcw. Chem. 50: 271—277. PHILLIPSON, J. 1964. A miniature Bomb Calorimeter for small biological Samples. OIKOS 15:1 Copen- hagen. PULLI, S. 1973. Yields, root development, carbohydrate reserves and in vitro dry matter disappearance of spring-seeded alfalfa, treated with herbicides and harvested in the year of seeding. Thesis MSU. 100 p. 1977. Sinimailasen kasvu, kehitys ja viljelytekniikka. Sinimailasen viljely ja käyttö. Hcls. Yliop. Kas- vinviljelytiet. lait. Julk. 2, 38—50. 1980. Tärkeimpien kasvutekijöiden ja käytetyn viljelytekniikan suhteet nurmen kasvurytmiin ja sa- donmääritykseen. J. Scient. Agric. Soc. Eini. 52: 185 330. RABINOWITCH, E. 1945. Photosynthesis and Related processes. 599 p. Voi. 1 Intcrscicncc pub. Inc. New York. RAININKO, K. 1973. Onko kasvinjalostuksella mahdollisuuksia parantaa nurmikasvien laatua? Karjatalous 5: 8-9. RAVANTTI, S. 195 5. Nurmikasvilajicmmc satoisuudesta. Koetoim. ja Käyt. 9: 112—118. 1965. Nurmikasvit. Hankkijan kasvinjalostuslaitos. Siemen julkaisu 1965: 142—149. REID, J.T., KENNEDY, W.K., TURK, K.L., SLACK., S.T., TRIMBERGER, G.W. & MURPHY, R.P. 1959. Effect of growth stage, chemical composition and physical properties upon the nutritive value of forages. J. Dairy Sci. 42; 567—571. SHANTZ, H.L. & PIEMESEL, L.N. 1927. The Water Requirement of Crops at Acron, Colorado. J. Agric. Res. 34: 1093-190. SMITH, D. 1962. Forage Management in the North. W.M.C. Brown Book Co. 219 p. Dubuque, lowa. 1969. Removing and analyzing Total Nonstructural Carbohydrates from Plant Tissue. Wisconsin Agr. Exp. Sta. Res. Rep. 41. 11 p. SOMOGYI, M. 1952. Notes on Sugar Determination. Journal of Biol. Chem. 195: 19—23. SYRJÄLÄ, L., SUVITIE, M. & SEPPÄLÄ, J. 1978. Timoteinurmen sato, koostumus ja sulavuus kasvukau- den eri aikoina. Kehittyvä Maat. 39: 27—35. TEITTINEN, P. 195 5. Näkökohtia sinimailasen viljelyssä. Karjatalous 9: 237. TESAR, MB. 1972. Effect of alfalfa seeding rates on yields in a 3-year period. NCR-31 Committee. Forage management and Physiology. & JACKOBS, J.A. 1972. Establishing the Stand. In C.H. Hansen (cd.), Alfalfa Science and Technolo- gy, ASA monograph, N:o 15, Amer. Soc. Agr. Madison, Wisconsin, p. 391—435. TILLEY, J.M.A. and R.A. TERRY. 1963. A two-stage technique for the in vitro digestion of forage crops. J. Brit. Grassl. Soc. 10: 104—111. WASSINK, E. 1948. Light as a factor in photosynthesis and its relation to other environmental factors. Me- ded. Dir. Tuinbouw 1 1: 503—513. Me received September 18, 1980. 494 SELOSTUS Viljelytoimenpiteiden ja kasvutekijöiden vaikutus kylvövuoden sinimailasen kasvuun Seppo Pulli Helsingin yliopisto, kasvinviljelytieteen laitos, 00710 Helsinki 71 Helsingin yliopiston kasvinviljelytieteen laitoksella tutkittiin vuosina 1973—74 niittojen ja kylvötiheydcn vaikutusta sinimailasen kylvövuoden sadonmuodostukseen sekä kasvun ja kehityksen suhdetta tärkeimpiin kasvu- tekijöihin kasvukauden eri ajankohtina. Tutkimuksesta voidaan vetää scuraavat johtopäätökset. Korkein kuiva-ainesato saatiin kylvösicmcnmäärällä 20 kg/ha. Suotuisan kasvukauden 1973 kylvövuoden kuiva-ainesato oli 5.7 tn/ha, kolean ja sateisen kasvukauden 1974 3.3 tn/ha. Sinimailasnurmcn yhteyttämiste- hokkuus oli 0.3—0.5 % pinta-alalle tulleesta kokonaissäteilystä. Pilvisenä kesänä 1974 saatiin 10 % vähemmän säteilyä kuin 1973. Kun yhteyttämistehokkuus oli v. 1974 lähes 50 % vähemmän kuin 1973, sadonmenetys on täytynyt johtua ensisijassa alemmista keskilämpötiloista ja haitallisen suurista sademääristä. Tehokas yhteyttämis- pinta saavutettiin siemcnmäärällä 5 kg/ha kylvövuoden syksyllä. Kylvöstä taimettumiseen tarvittiin 120°C ja kylvöstä kukkimiseen 800°C. Niitosta kukkimiseen tarvittiin 600—700°C lämpösumma. Kylvövuoden sinimailasen juuriston vararavintovarat osoittavat, että sinimailanen voidaan niittää vain kah- desti, viimeisen niiton tapahtuessa elokuun puolivälissä.