Morphological and water-stress characteristics of three Douglas-fir stocktypes in relation to seedling performance under different soil moisture conditions

✍ Scribed by R. Rose; J. F. Gleason; M. Atkinson

• Publisher: Springer Netherlands
• Year: 1993
• Tongue: English
• Weight: 868 KB
• Volume: 7
• Category: Article
• ISSN: 0169-4286
• DOI: 10.1007/bf00037468

✦ Synopsis

This one-time greenhouse study examined the phenology, morphology, frost hardiness and response to moisture stress of three Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) stocktypes from the same seed lot. The types were mini-plug TM transplants (MPT), 1 + 1 bareroot transplants (1 + 1), and 2 + 0 barefoot seedlings (2 + 0). In late summer and fall before lifting, 2 + 0 seedlings set bud before 1 + 1 seedlings, 1 + 1 seedlings before MPT seedlings, The 2 + 0 seedlings appeared slowest to acquire frost hardiness in fall and seemed to deharden most rapidly in spring. Although the 2 + 0 seedlings were taller than the MPT stocktype, MPT and 2 + 0 seedlings were relatively similar in other morphological respects, but 1 + 1 seedlings were much larger. All stocktypes were potted on January 20, 1989, placed in a greenhouse, and subjected to 39%, 18%, 16%, or 6% soil water content (% dry weight) until the end of the experiment in mid-July 1990. The largest decrease in pre-dawn xylem water potential occurred with 16% and 6% soil water content; pre-dawn xylem water potential averaged over the three stocktypes generally declined 219% from low to high soil moisture stress. The 1 + 1 seedlings used more water than the other two stocktypes, and at maximum soil moisture stress, plant moisture stress increased in the order: MPT < 2 + (I < 1 + 1. During the 6-month greenhouse experiment, the larger 1 + 1 stocktype showed the most absolute growth, but the smaller stocktypes grew more on a relative scale. Growth of the stocktypes appeared to be related to differences in morphology and water-use patterns as the seedlings competed for available water within each pot. The results show that MPT seedlings, a new stocktype, performed as well as the more traditionally used 2 + 0 and 1 3-1 seedlings and that stocktype selection is important in reforestation efforts.

Application.Seedlings of three different stocktypes (mini-plug ~ ~ transplants, 2 + 1) bareroot, and 1 3-1 transplants) responded differently to various levels of soil moisture content. Results indicate that mini-plug TM seedlings, a new stocktype, may be an excellent alternative to more traditionally used 2 + 0 and 1 + 1 stocktypes.