Fall Acclimation and the Lift/Store Pathway: Effect on Reforestation

Abstract

This review compares fall acclimation patterns and lift/store practices for Pseudotsuga menziesii var. menziesii, Picea glauca (Moench) Voss x P. engelmannii Parry ex engelm and Pinus taeda L. seedlings. Spruce seedlings achieve budset and an endodormant state in late summer, coastal Douglas-fir in early fall, while loblolly pine achieves a less endodormant state with a limited amount of mitotic activity. Natural chilling during the fall reduces days to budbreak (DBB) and increases freezing tolerance, with northern species achieving greater freezing tolerance. Although root growth potential (RGP) in some years may increase from early fall to midwinter , this trend does not always occur. Chilling hours and/or freezing tolerance status is used to initiate storage of Douglas-fir and spruce seedlings but there is no proven attribute to make the lifting decision for loblolly pine. When properly hardened, all species can be cooler stored to meet lift/store requirements of a few months, though fall lifted interior spruce seedlings are typically freezer stored for up to six months. Lengthy storage can cause declines in DBB, freezing tolerance, RGP, and carbohydrate reserves. Douglas-fir and interior spruce seedlings require an appropriate length of fall acclimation, typically including chilling, to develop a level of hardiness for lengthy storage and high survival after outplanting. Loblolly pine seedlings benefit from chilling, though non-chilled, hardened seedlings may exhibit high survival after four weeks of cooler storage. Each species has a unique fall acclimation pattern making it difficult to define universal culture practices across all regional forest regeneration programs.

The role of stored carbohydrates and nitrogen in the growth and stress tolerance of planted forest trees

“…For instance, seedlings stored in darkness in refrigerated systems may have lower outplanting performance if not adequately hardened or stored for extended periods of time (Grossnickle and South 2014). Poor field performance of cold stored plants has been attributed in part to strong reduction in NSC levels (Ritchie 1982, Table 5).…”

“…Seedling quality is strongly influenced by nursery cultivation practices such as irrigation, fertilization, hardening, cold storage, and lifting/store or handling (van den Driessche 1991b;McKay 1997;Wilson and Jacobs 2006;Islam et al 2009;Grossnickle 2012;Grossnickle and South 2014). These manipulations may result in changes in seedling size, root/shoot biomass allocation, cold hardiness, dormancy development, stress tolerance and storage reserves that affect subsequent seedling outplanting performance (Grossnickle 2012).…”

Forecasting the field performance of Austrian pine seedlings using morphological attributes

“…Stock types should be tested in field trials for a number of years to ensure a representative assessment of field performance (Pinto et al 2011a). Between lifting and planting, seedlings are potentially exposed to numerous stresses (McKay 1997, Grossnickle & South 2014. Moreover, environmental conditions differ between sites and even between single planting spots (Grossnickle 2000).…”

Seedling Quality: History, Application, and Plant Attributes

“…However, root electrolyte leakage is measured during crop development if there is a concern about damage. Furthermore, measuring chlorophyll fluorescence, electrolyte leakage, or whole-plant freezing during crop development in the autumn provides an assessment of freezing tolerance, with the goal of determining the proper lift/store date to develop sufficient stress resistance so high quality seedlings are stored (reviewed by [109,132,133]). Finally, at lifting, various morphological attributes, together with the physiological attributes of plant water relations, freezing tolerance, mineral nutrient status, root growth potential, and root electrolyte leakage are commonly assessed (See Section 3.2).…”