The influence of acclimatization treatment and plantlet morphology on early greenhouse-performance of tissue-cultured Douglas fir [Pseudotsuga menziesii (Mirb.) Franco]

Abstract

The objective of this investigation was to test for the possible effects of plantlet morphology and environmental stress on survival and growth during the acclimatization of tissue-cultured Douglas fir [Pseudotsuga menziesii (Mirb.) Franco]. Under a high-stress environmental regime of 40-70% relative humidity and 22-28°C, survival was 33%, compared to 89% under a low-stress regime of 80-90% RH and 15-20°C. Shoot elongation under low stress was twice as great as that under high stress. Certain morphological features were associated with improved survival under high stress, and they included a large (10+) root number, tall (40 + mm) shoots, and upright needles. Plantlets with 10 + roots had 52% survival, compared to 25% or 31% for those with 1-3 or 4-10 roots, respectively. Also, plantlets with an initial shoot height of 41-60 mm had a 53% survival rate compared to 20% or 37% for those with 21-30mm or 31-40ram shoots. Tall plantlets and those with 10+ roots also underwent the greatest shoot elongation during the 7 week observation period. However, plagiotropism was frequent on tall shoots.

Elongation, rooting and acclimatization of micropropagated shoots from mature material of hybrid larch

“…Although in vitro shoots of Larix species were rooted before as short shoots and elongation occurred after acclimatization (Bonga &von Aderkas, 1988;Lalibert6 & Lalonde, 1988), rooting and acclimatization are generally more successful with longer shoots. With L. decidua the shoots had to attain a length of 10 mm (Diner, 1990) and those of Pseudotsuga menziesii, a length of 30 mm before they would root (Mapes et al, 1981) with an initial height of 41-60 mm giving the best percentage of plantlet survival in the latter (Mohammed & Vidaver, 1990).…”

Adventitious rooting of conifers: influence of physical and chemical factors

“…In vitro rooting of conifer microshoots usually occurs in gelled nutrient media (mostly agar-and gellan-gum based) as substrate. This ensures the consistent distribution of PGRs, macro-and micronutrients, and also provides a better contact between shoots and substrate, resulting in more synchronous rooting (Mohammed and Vidaver 1990). However, the quality of produced roots is not always satisfactory.…”

“…An efficient rooting treatment can lead to a high percentage of rooting and a higher quality of the root system (De Klerk et al 1997). Quality involves root number and length, and the absence of callus at the base of a shoot, all of which influence the performance of the plants after transfer to soil (Mohammed and Vidaver 1990). Many factors, during the rooting phases, can cause poor quality of the shoots at the time of planting, thus affecting growth (De Klerk et al 1999;Hartmann et al 2002;Mohammed and Vidaver 1990).…”

Estímulo do comportamento fotoautotrófico durante o enraizamento in vitro de Annona glabra L. , II. Aspectos da anatomia da folha antes da aclimatização

“…Um eficiente sistema de enraizamento deve apresentar alta porcentagem de brotos enraizados e sistema radicular de alta qualidade com a formação de número e comprimento de raízes adequadas e a ausência da formação de calo (KLERK et al, 1997;MOHAMMED & VIVALDER, 1990).…”