Technical resource bulletin. TRB-007, Effects of extended cold storage on the survival and performance of container grown longleaf seedlings

Technical Resource Bulletin TRB-007 January 2012 Effects of Extended Cold Storage on the Survival and Performance of Container Grown Longleaf Seedlings Bill Pickens. NC Forest Service, Raleigh NC Abstract: - This study evaluates the effects of extended cold storage on the survival and growth performance of container grown longleaf seedlings. The seedlings were lifted on four different dates in October and November, stored, and out-planted every two weeks up to a 10 week storage length. Seedlings were measured for: l ) Survival at age one, 2) number out-of-grass stage at age two, 3) height at age two, and 4) height and DBH (diameter at breast height) at age eight. The study shows that length of storage affects the survival and performance of container grown longleaf pine. Sur¬ vival was significantly lower for seedlings stored longer than six weeks. Storage for more than two weeks reduced the number of seedlings that initiated height growth and height of those seedlings tat age two. Affects of storage length on growth are still present at age eight. At age eight, seedlings stored two weeks or less have significant¬ ly better height and DBH. A significantly higher number of seedlings not stored, or stored for only two weeks, initi¬ ated height growth at the end of two years than those stored longer than four weeks. The date seedlings are lift¬ ed had no apparent affect on survival, but did affect early growth. Significantly more seedlings lifted on October 2 or October 16 initiated height growth at age two than those lifted October 30th and November 1 3th. However, lift date affects on height and DBH were not retained and were not present at age eight. Planting date affected seed¬ ling survival and out-planting performance. Seedlings planted before mid-November are taller and have a higher percentage of seedlings out-of-the grass stage at age two. Study data suggest that for best survival and perfonnance container grown longleaf seedlings should not be stored longer than two weeks. While not a part of this study re¬ sults support the recommendation that fall planting im¬ proves early growth but does not necessarily improve sur¬ vival. Introduction Research has documented the survival of bareroot long¬ leaf pine (Pirns palustris) is significantly reduced by ex¬ tended cold storage '. Similar research for container grown longleaf seedlings has not been conducted 2. An increase in the demand for containerized seedlings has occurred across the Southeast over the last decade. In re¬ sponse nursery production increased to its current level of thirty million seedlings annually3. To meet the needs of its customers, the nursery manager must store an increasing number of container longleaf seedlings for extended peri¬ ods. Without storage, inventory losses to seedlings left on the benches exposed to extended periods of freezing tem¬ peratures are possible. Extended storage allows the nurse¬ ry manager to utilize lifting and packing crews efficiently. Nursery managers need to know how long container long¬ leaf seedlings can be stored without affecting out-planting survival. With this information decisions concerning lift¬ ing schedules, inventory control, and protecting the seed¬ lings from freezing temperatures can be made. Methods The test was initiated in the fall of 2001 on a site at the Bladen Lakes State Forest in southeastern North Carolina. 1 20 container grown longleaf seedlings were lift¬ ed at the N.C. Divi¬ sion of Forest Re¬ sources Claridge Nursery on four different dates; Oc¬ tober 5th, October I6,h, October 30th, and November I3lh. The 480 total seed¬ lings lifted were boxed and stored at 35 degree Fahren¬ heit for periods of zero storage, two week, four week, six week, eight week, and Ю week. The 24 treatments