Effects of Seeder Design and 

 Seed Placement on Seedling 

 Size and Cull Rates at Western 

 Forest Nurseries 



John P. Sloan 



INTRODUCTION 



Uniform spacing between seedlings is important 

 to the efficient operation of forest tree nurseries. 

 The value of western conifer seed continues to in- 

 crease due to dwindling amounts of some seed 

 sources, growth of genetically improved seed, and 

 more costly, nondestructive seed collections from 

 high-quality stands and trees. It is becoming more 

 and more costly for nurseries to raise unacceptable 

 seedlings that must later be discarded. Nursery 

 managers would like to make better use of precious 

 seed supplies, reduce the proportion of nonshippable 

 trees, and produce more uniformly sized seedlings 

 through more uniform spacing of trees. Seedlings 

 raised in such conditions might perform better when 

 planted in the field. However, we must place seed 

 more precisely during sowing to obtain more uni- 

 form spacing between seedlings in the nursery bed. 



In seedbed tests at five Forest Service, U.S. De- 

 partment of Agriculture, nurseries during the spring 

 of 1985, the Love/Oyjord seed sower and the Summit 

 Precision Seeder differed in seed placement (Sloan 

 1990). In addition, seed placement using these two 

 seeders and hand thinning were compared in exten- 

 sive study plots to determine the effects on seedling 

 spacing, seedling morphology, and cull rates. We 

 studied 26 different seedlots, including nine species. 



MATERIALS AND METHODS 



The five Forest Service nurseries participating in 

 this study were Coeur d'Alene Nursery, Coeur d'Alene, 

 ID; Lucky Peak Nursery, Boise, ID; J. Herbert Stone 

 Nursery, Central Point, OR; J. W. Toumey Nursery, 

 Watersmeet, MI; and Wind River Nursery, Carson, 

 WA. The study was a cooperative effort between the 

 nurseries, the Forest Service's Missoula Technology 

 and Development Center, and the Forest Service's 

 Intermountain Research Station. 



Both seeders were calibrated to sow at each 

 nursery's target rate, based on species, seedlot ger- 

 mination rate, and a niirsery loss factor. The nursery 



loss factor came from production records. Seeds 

 were covered with aluminum powder before sowing 

 to make them readily visible and facilitate smooth 

 flow through the seeders. 



We rgui the seeders using seed from nine conifer 

 species. Douglas-fir (Pseudotsuga menziesii var. 

 menziesii and var. glauca [Beissn.] Franco) (coastal 

 and inland varieties) was sown at three nurseries. 

 Both Engelmann spruce (Picea engelmannii Parry 

 ex Engelm.) and ponderosa pine {Pinus ponderosa 

 Dougl. ex Laws.) were sown at two nurseries. White 

 spruce {Picea glauca [Moench] Voss), noble fir {Abies 

 procera Rehd.), jack pine {Pinus banksiana Lamb.), 

 lodgepole pine {Pinus contorta var. latifolia Engelm.), 

 red pine {Pinus resinosa Ait.), and western larch 

 {Larix occidentalis Nutt.) each were sown at one 

 nursery (table 1). 



Four species were sown at the Lucky Peak Nurs- 

 ery; three were sown at the Coeur d'Alene Nursery 

 and the J. W. Toumey Nursery; two were sown at 

 the J. Herbert Stone Nursery; and only noble fir 

 was sown at the Wind River Nursery (table 1). 



Each species at a nursery was treated as a sepa- 

 rate test. Within each test, we sowed two seedlots. 

 The first had about a 95 percent germination rate; 

 the second had a 75 to 85 percent germination rate. 

 Within each of three blocks, six plots were arranged 

 randomly. Each of the six plots received one of the 

 three treatments with one of the two seedlots. The 

 treatments were: (1) seed sown using the Summit 

 Precision Seeder calibrated to the target spacing, 

 (2) seed sown using the Oyjord Seeder calibrated to 

 the target spacing, and (3) seed oversown using the 

 Oyjord Seeder and hand thinned to the target spac- 

 ing after seedling emergence. Treatments were 

 randomly arranged in blocks. 



All plots were 6 meters long with a 1-meter buffer 

 separating the plots. Three 0.5-meter sample plots 

 were placed within each plot. After sowdng, a meter- 

 stick was laid alongside each row in a sample plot, 

 and the position of every seed was recorded in milli- 

 meters. As soon as the measurements were made, 

 the seed was covered with sand. 



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