Lavender, Denis P.

Oregon Forest Lands Research Center

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Research NoteeNo. 32Effect of Seed Size onDouglas Fir SeedlingsOregonLForest Lands Research CenterDick Berry, DirectorCorvallis, Oregonanybycam'YipForest Lands Research Center. Its PurposeDevelop the full potential of Oregon's timber resource by:increasing productiveness of forest lands with improved forestpractices.improving timber quality through intensified management and superiortree selection.reducing losses from fire, insects, and diseases-thus saving timberfor products and jobs.Keep development of the forest resource in harmony with development ofother Oregon resources.. .. Its Current ProgramSeed production, collection, extraction, cleaning, storage, and germination.Seedling production, establishment, and survival for new forests.Growth and development of trees, quality of growth, and methods ofthinning and harvesting to grow improved trees.Study of forest fire behavior and fire weather to prevent fires.Insect pests and their control, to save trees.Disease control and prevention in Oregon forests.Mammal damage and the controls to help regrowth.Soils and their relationship to growth.Development of improved forests through selection and breeding.Effect of Seed Size onDouglas Fir Seedlingsby Denis P. LavenderIntroductionIncreased importance of artificial regeneration in Douglas fir (Pseudo-tsuga taxifolia Poir) silviculture and more emphasis upon developing a su-perior planting stock have necessitated an increased understanding of thegrowth habits of Douglas fir seedlings. With nursery space at a premium,the nurseryman must sow his beds with seeds producing maximum quantity andtop-quality growing stock. In tree breeding, successful experiments re-quire elimination of factors that may mask true hereditary effects upongrowth rates of seedlings. One obvious factor possibly affecting seedlingsize and vigor is the size of the seed employed in planting or experimen-tation. Many investigators have studied intensively the effects of seedsize upon resulting agricultural crops but relatively little is known aboutsuch effects upon trees. This is especially true for tree seedlings two ormore years old.Table I summarizes some of the experimental work thus far undertaken.In addition, Baldwin (2) reviews the work of several investigators who foundthat seed size exerted a definite effect upon resultant seedling size duringthe first growing season in several species of Pinaceae. Eliason and Heit(3) found a non-significant relationship between Pious sylvestris seed weightand its green seedling weight after two years, and between E e seed weightand seedling height and diameter after three years. Spurr (8) states that:"The correlation between (seed) weight and shoot weight diminishes as theplant ages, but is still noticeable after three years." (For Pinus strobus.)Table I: Relation of Seed Size to Seedling DevelopmentSpecies Relationship Duration of EffectYearsEuropean chestnut ................. ..Silver fir ........................ +, - 2-4European larch .................... + 1-4Norway maple ...................... + 3+Russian mulberry .................. +Durmast oak ....................... + 2+English oak ....................... + 1+Northern red oak .................. + 1+Austrian pine ..................... + 2-7Chir pine ......................... +Scotch pine ...................:... + 2-6Sal shorea ........................ + 2-6Norway spruce .....................Teak ..............................++,'b.2-7Woody-Plant Seed Manual, USDA Misc. Pub. No. 6541--Collection and Storage of Experimental SeedSeeds for this study were collected in the drainage of the NorthSantiam River at an elevation between 1.000 and 2,000 feet during the fallof 1954. The seeds were stored at 0 until the spring of 1955.Separation of Experimental Seed by DensityIn May of 1955, fifty pounds of seed (approximately 2,000,000 seeds)were fractioned on a South Dakota Blower (plates 1 and 2). This machinedivides seed lots on the basis of the density of each seed. At a givensetting, the velocity of the rising column of air causes removal of theleast dense, but not necessarily the lightest, seeds. Thus, fractions ofincreasingly dense seeds may be segregated as the velocity of the ascend-ing column of air is increased. This procedure provides precise, repro-ducible fractions of any given seed lot.The fifty pounds of seed were divided into three lots with approxi-mately the following number of seeds per pound in each lot: heavy--37,000; medium--42,000; and light--47,000.1 The mean weight of heavy seedswas approximately 28 per cent greater than that of light seeds. Probablythe difference could have been increased by further fractioning of theseed. The heavy fraction represented about 20 per cent of the original lot;the light, 50 per cent. Since this study was designed to provide dataapplicable to large scale nursery operations, it was decided that anyfurther refinement would be impracticable.PretreatmentThe seeds were stored in a moist medium at from 34 F to 39 F (strati-fication) for six weeks. Random samples of each lot were secured forcutting tests (200 seeds per test) and laboratory germination test (400seeds per test) (4). The heavy and medium fractions had 100 per cent soundseeds while the light fraction equaled 88 per cent sound. Heavy seed germi-nation was 95 per cent as opposed to 90 per cent for the medium seeds and82 per cent for the light. An even clearer indication of the greater vigorof the heavy seed may be seen by comparing germination rates after one weekin the germinators. At this time the heavy seeds had 89 per cent germi-nation; the medium, 75 per cent; and the light, 59 per cent.Experimental AreaNine adjoining beds, 350 feet long, in the Oregon State Forest Nurserynear Corvallis, Oregon,were designated as the experimental area. The light-seed lot was drilled in four randomly selected beds; the medium, in three;and the heavy, in two. The beds, of eight rows each, were seeded at a rateof 62 seeds per foot on May 20, 1955.1. These figures are based on the weight of seeds only and corres-pond to the following data for seed lots commercially cleaned; i.e. withsome foreign material; 32,000, 41,000, and 44,000.2Plate 1. South Dakota Blower. Ma-chine developed for cleaning agri-cultural seed with an ascending col-umn of air. Separates seed on adensity basis; light, blank seeds aretrapped in cups at the upper end oftube while heavy, sound seeds remainin the lower reservoir.Plate 2. Movable head controls airstream in tube. A uniform seed lotmay be obtained by "blowing" smallincrements at identical time and windsettings.3Sampling and Measurement ProcedureIn November 1955 samples of the one-year seedlings were harvested inthe following manner:1) Twelve randomly located, one-foot lengths of seedbed were se-lected for each treatment. (Bed number, row, and distance infeet from the end of the bed were assigned through use of atable of random numbers. Outside rows in each bed were notused to avoid possible border effects.) Because the beds didnot appear uniformly fertile, half of the samples for eachtreatment were located in the upper end of the beds (StratumI) and half in the lower end (Stratum II).2) All seedlings in each foot of seedbed were dug up for labo-ratory examination.In the laboratory the seedlings were carefully washed and the followingdata recorded:1) Shoot length, length of roots, arid total length of eachseedling.2) Number of living and dead seedlings in each sample.3) Total weight of shoots and total weight of roots for livingseedlings in each sample.The seedlings were then stored for three :aonths at 80 F and weighed atintervals until constant weights were reached. These weights were con-sidered to be the "air-dry" weights of each seedling group and formed thebasis for the data presented in tables in this report.A procedure similar to that outlined above was followed in the fall of1956 to sample and measure the two-year-old seedlings.ResultsData presented in tables II to VI indicate the following facts:1) Size and weight of resulting Douglas fir seedlings are notaffected by the seed weights.2) Heavy seeds produced approximately 50 per cent more livingtwo-year-old seedlings for every seed sown than did the lightseeds.3) There was no correlation between seedling mortality andseedling size.4DiscussionComparison of tables II and IV indicates considerable difference in thenumber of living two-year-old seedlings produced by the light seeds. Inas-much as the data recorded in table II represent the total experimental popu-lation and not just a sample of it, they are obviously accurate. The dis-parity between the actual number of seedlings grown and the number esti-mated may be a sampling error due to the sporadic nature of the stocking ofthe beds sown with light seeds, Clumps of relatively thickly spacedseedlings were interspersed with completely vacant spaces. This stockingpattern was probably due to the seeds not being sown an absolutely uniformdistance beneath the soil surface, and the light seeds (as previouslynoted) were not sufficiently vigorous to emerge from the soil in areas ofdeeper sowing.Plate 3. These two-year-old seedlings aretypical of those produced by the different seedfractions during this study.In addition to a tally of the total number of seedlings produced fromeach seed weight, a tally was also made for each seed weight of allseedlings whose tops exceeded four inches. This showed that 85 per cent ofthe seedlings produced by light seeds were over four inches tall; 83 percent of the seedlings produced by medium seeds were taller than four inches;and 68 per cent of the seedlings produced by heavy seeds were over fourinches in height. Even when samples determining seedling size indicatedthat the light seedlings were under greater competition than correspondingheavy seedlings, seedlings grown from the light seeds were larger thanthose grown from heavy seeds. It must therefore be concluded that thegreater number of seedlings in beds sown with heavy seed did not cause theirrelatively inferior size.ConclusionsData presented in this report show that nurserymen cannot expect toproduce larger seedlings merely by using the heaviest fraction of a givenlot of Douglas fir seed. It is possible, however, to utilize the nurseryarea more completely by seeding the beds with seeds of the highest possiblegerminative vigor. A relatively small decrease in germinative vigor asmeasured by laboratory tests can mean a substantial reduction in cropseedlings in the nursery.5Table II: Total Nursery Tally of TEro-year-old Seedlings Lifted,from Experimental BedsSeed Total numberTotal numberof feetMean number- of seedlings perweight of seedlings of seedbed foot of seedbed.Light .......... 226,000 11,200 20.18Medium......... 182,000 8,400 21.67Heavy .......... 172,000 5,600 30.71Mean........... ----- ---- 23.02YTable III: Seedling Mortality"MortalitySeedweight 1955 1956 , . TotalLight .......... 3.2 9.8 13.0Medium ......... 4.8 12.1 17.9Heavy .......... 2.9 8.5 11.4Table IV: Number of Living Seedlings per Sample UnitOne-year-old seedlingsSeed weight Number of seedlingsStratum Average1 2Light ........ 24.0 22.0 23.0Medium....... 33.0 27.0 30.0Heavy........ 40.0 32.0 36.0Two-year-old seedlingsSeed weight Number of seedlingsStratum Average1 2Light ........ 35.0 28.0 31.0Medium....... 27.0 23.0 25.0Heavy........ 32.0 25.0 28.04:Table V: Total Seedling Weight (Root and Top)One-year-old seedlingsSeed weight Seedling weight1Stratum2AverageLight......... 0.27Grams0.19Grams0.23Medium........ 0.26 0.25 0.26Heavy......... 0.34 0.22 0.28Two-year-old seedlingsSeed weight Seedling weight1Stratum2AverageLight......... 1.05Grams0.98Grams1.02Medium........ 1.30 1.11 1.22Heavy......... 0.89 0.98 0.93Table VI: Total Seedling Length (Root and Top)One-year-old seedlingsSeed weight Seedling lengthStratum2AverageInches InchesLight .......... .8.3 6.9 7.6Medium......... 8.5 8.4 8.5Heavy.......... 9.0 7.3 8.3Two-year-old seedlingsSeed weight Seedling lengthStratum Average1 2Inches InchesLight .......... 12.3 12.4 12.4Medium.........13.2 12.6 12.9Heavy .......... 11.7 12.1 11.97BIBLIOGRAPHY1. Aldrich-Blake, R. N. The plasticity of the root system of Corsican pinein early life. Oxford Forestry Mem. 64 p. 1930.,2. Baldwin Henry Ives. Forest tree seed of the north temperate regions.1942.3. Eliason, E. J. and C. E. Heit. The size of Scotch pine cones as relatedto seed size and yield. Journal of Forestry. Vol. 38 No. 1.1940.4. Lavender, Denis P. and Wilbur H. Engstrom. The viability of seeds Pramsquirrel-out Douglas fir cones. Salem, March 1956. (Oregon StateBoard of Forestry. Research Note No. 27)-5. Mitchell, Harold L. Pot culture tests of forest soil fertility. BlackRock Forest. Bulletin No. 5. 138 p. 1934.6. The growth and nutrition of white pine (Pinusstrobus L.T seedlings in cultures with varying nitrogen, osphoruspotassium, and calcium with observations on the relation of seedweight to seedling yield. Black Rock Forest Bulletin No. 9. 135 P-1939.7. Righter, F. I. Pinus: The relationship of seed size and seedling sizeto inherent vigor. Journal of Forestry 43:131-137. 1941-8. Spurr, Stephen H. Effect of seed weight and seed origin on the earlydevelopment of eastern white pine. Journal Arnold Arboretum25:467-480. 1944.9- Woody-plant seed manual. Washington, GovernmentPrinting Office. (U. S. Department of Agriculture. Misc. Pub.No. 654).THE OREGON FOREST LANDS RESEARCH CENTER program is guided byrepresentatives of public and private land owners who are interested in the bestuse of Oregon's forest land resources,The following men constitute current membership:NAT GIUSTINA, Principal . .DAVE BURWELL, AlternateGENE KNUDSON, Principal . .WILLIAM D. HAGENSTEIN, AlternateT. J. ORR, Principal . .A. W. MOLTKE, AlternateB. SAM TAYLOR, PrincipalROBERT KLINE, AlternateJOSEPH W. MCCRACKEN, PrincipalSAM R. KONNIE, AlternateR. W. COWWLINRUSSEL GETTYGEORGE H. BARNES .. .. , s c>D. L. PIIIPPsWillamette Valley Lumbermen'sAssociationIndustrial Forestry Association. Western Pine AssociationSouthern Oregon Conservation andTree Farm AssociationWestern Forest IndustriesAssociationPacific Northwest Forest andRange Experiment StationBureau of Land ManagementSchool of ForestryState ForesterThe Forest Protection and Conservation Committee, established in 1953,administers research funds and approves research projects. Present members are:SIDNEY LEIKENA. C. ROLL . .WALTER F. MCCULLOCIIELIOT JENKINS .FREEMAN SCHULTZ .Western Forest Industries Association. . . . . Member at LargeSchool of ForestryWest Coast Lumbermen's Association. . . Western Pine Association. . ..

Effect of seed size on Douglas Fir seedlings

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Effect of seed size on Douglas Fir seedlings

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