Wet and Waxy Shoots in Radiata Pine Micropropagation

A novel system for in vitro shoot production has been developed whereby shoot hedges are maintained in one vessel. Monthly crops of shoots are produced for rooting. Radiata pine shoot hedges were maintained on Lepoivre (LP) nutrient agar medium for 18 months using a weekly liquid-nutrient replenishment system. In a separate experiment liquid-LP-nutrient replenishment of shoots twice weekly without transfers (D) resulted in better shoot growth and health than monthly transfers to fresh agar medium (B), monthly transfers to fresh agar medium plus aeration twice weekly (C), or no transfers and no liquid nutrient addition (A). Liquid nutrient replenishment twice weekly was better than 2 weekly or 4 weekly replenishment. The percentage of normal waxy (abundant tubular epicuticular wax) shoots harvested monthly increased significantly over the culture period from 41% at the first harvest to 93% at the eight harvest, and remained high at 97% from the ninth to twelfth harvest. The percentage of wet (no tubular epicuticular wax, small amounts of globular epicuticular wax) shoots harvested showed a corresponding decline --from 59%, to 7% at the eighth harvest. Shoots were harvested at a rate of 672/h (I. 19 cents/shoot at a labour cost of NZ$8.00/h) and approximately 1100 shoots were produced per square metre of agar surface per month. Initial problems of contamination and crowding were overcome. These results will greatly facilitate progress towards automation of shoot production and reduction of costs of micropropagated trees. An automated system used in combination with other cost-saving techniques or robotics could potentially result in a substantial reduction in costs. This is the first report of a method of culturing shoots as hedges for a period of up to 18 months without manual subculturing.

Section: Discussionmentioning

confidence: 59%

Section: Discussionmentioning

confidence: 99%

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Towards automation: Radiata pine shoot hedges in vitro

Aitken-Christie

Jones

1987

“…Shoot height was significant in Douglas fir [20] and radiata pine [133], where 4 cm for fir and 2.4-2.7 cm for pine were best for rooting. 'Vitrification' [79] or 'translucence' [3,152] has resulted in lower rooting in sitka spruce [79], Norway spruce [152] and radiata pine [3], and was also associated with poor survival during acclimatization. Vitrification has many causes but can often be prevented by high gel concentration and low BA in the medium [110,154].…”

Section: Other Factors Which Affect Rootingmentioning

confidence: 99%

Root production and plantlet development in tissue-cultured conifers

Mohammed¹,

Vidaver

1988

Rooting and acclimatization procedures for micropropagated conifers are reviewed, with emphasis on their effects on root quality and plantlet performance in the nursery and field. Major influences on root production include auxin concentration and mode of application, shoot quality, donor age, clone and temperature. The development of a fibrous, well-branched root system has been a problem that may be solved by using rooting substrates that are better-aerated than agar. Further development of the root system may be enhanced by early air-pruning and ectomycorrhizal associations. During acclimatization, high humidity is required for conifers. However, conifers have an advantage over non-coniferous plantlets with respect to water loss because of a better development of the needle cuticles prior to transfer to in vivo conditions. In greenhouse and field comparisons with seedlings, plantlets were similar in survival and growth rate, but root systems were less fibrous. Also, features of early maturation have been observed for plantlets, the cause of which is uncertain. Pertinent research with rooted cuttings and seedlings of conifers has been cited to gain a better understanding of the factors involved in root production and development.

“…comm.) and loblolly pine (Pinus taeda L.) [11], shoot quality [23] and root system morphology [2,13] for loblolly pine and white spruce [20], and the presence of roots for Norway spruce (Picea abies (L.) Karst) [22]. No reports are available for Douglas fir which is a species of considerable economic interest in the Pacific Northwest.…”

Section: Introductionmentioning

confidence: 99%

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

Mohammed¹,

Vidaver

1990

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.