The effect of cultivation technique on root and shoot biomass production by young Sitka spruce (Picea sitchensis (Bong.) Carr.) trees on surface water gley soils

In Ireland much of the land available for plantation establishment requires some degree of soil cultivation and drainage to improve its suitability for tree growth. The method of cultivation and drainage normally varies depending upon the soil type and its drainage characteristics. Little research has been carried out on the impact of practices such as mounding and mole drainage upon rooting and biomass production in young crops. The research reported in this paper was carried out on four sites where the general soil type was surface water gley. Three of the sites studied were afforestations on old farmland, while the fourth site was a reforestation of a windblown stand. The cultivation methods investigated included mounding, mole drainage with mounds, mole drainage only and ripping. Sitka spruce trees ranging in age from five to thirty years were excavated from these experimental sites to describe the impact of different soil cultivation techniques upon root architecture and above and below ground biomass production. The results showed that while the effect of mound drainage upon water table level varied from site to site, the establishment of trees on mounds led to an increase in above and below ground biomass production. Mole drainage of these sites without mounds, did not lead to any increase in root or shoot development when compared with trees growing on uncultivated/undrained ground. This revised version was published online in June 2006 with corrections to the Cover Date.     

A set of microsatellite markers for use in Sitka spruce (Picea sitchensis) developed from Picea glauca ESTs

Few microsatellite markers have been specifically developed for Picea sitchensis. In January 2004 the appearance of over 10 000 sequences of expressed regions of DNA from P. glauca in GenBank presented an opportunity for the development of additional microsatellite markers in Sitka spruce. Mono‐ and dinucleotide repeat sequences were located in these sequences and primers were designed around these regions. Amplification was attempted in Sitka material from a broad geographical range and the level of polymorphism was assessed. Primers were also tested in progeny of a controlled cross. Nine polymorphic loci that demonstrated Mendelian inheritance in Sitka were discovered in this study.     

The effects of SO2 and O3 on the foliar nutrition of Scots pine, Norway spruce and Sitka spruce in the Liphook open-air fumigation experiment

Foliar elements were analysed in Scots pine, Sitka spruce and Norway spruce over a 6 year period before and during continuous exposure to SO₂ and O₃ in an open-air fumigation experiment. Sulphur dioxide treatment elevated foliar sulphur concentration in all species, and there were increases in foliar nitrogen in the two spruce species but not in pine. The concentrations of cations were frequently increased by SO₂ treatment, but there was no correlation between the sulphur concentration of needles and their total cation charge. SO₂-related elevations of foliar magnesium were correlated with the concentration of this element in soil solution, but the mechanism by which other cations were enhanced remains unclear. The only consistent effects on nutrient ratios were for SO₂ treatments to increase sulphur/cation ratios.     

Variation of Microfibril Angle Between Four Provenances of Sitka Spruce (Picea sitchensis [Bong.] Carr.)

Abstract: The mean microfibril angle (MFA) of tracheids in Sitka spruce ( Picea sitchensis [Bong.] Carr.) from four provenances was determined by X-ray diffraction. Seeds were from four locations in North America: California, Oregon, Queen Charlotte Islands and Washington. Transplants were planted in 1976 and grown in Ireland (Shillelagh Forest). The mean MFA close to the pith was ca. 22° and decreased to ca. 11° in the outer rings. It was found that the MFA varies strongly not only as a function of the annual ring and the distance from pith but also as a function of the seed origin. Trees of California and Queen Charlotte Islands provenance had a larger mean MFA in general than trees of Washington and Oregon provenance. Also, the shapes of the cell cross sections were determined to some extent from the diffraction patterns. For samples of California and Washington provenance the average thickness of the cellulose crystallites was determined to be about 3.0 nm.     

Seasonal changes in the distribution of green spruce aphid Elatobium abietinum (Walker) (Homoptera: Aphididae) in the canopy of Sitka spruce

1 Seasonal changes in the distribution of green spruce aphid Elatobium abietinum (Walker) within the canopy of 20–25‐year‐old Sitka spruce are described based on data from two low‐altitude sites (310–420 m above sea‐level), two mid‐altitude sites (500–550 m a.s.l) and one high‐altitude site (610 m a.s.l). 2 Aphids were counted throughout the canopy on shoots representative of all needle age‐classes present at each whorl of branches. Counts were made during the middle week of each month from September to July for 4 years (1999–2003), and mean E. abietinum densities at each canopy position were calculated separately for each month and for the low‐, mid‐ and high‐altitude sites. 3 During September to November, the highest densities of E. abietinum occurred on 3–4‐year‐old needles on branches low in the canopy. Over the winter and spring, the centre of the aphid’s distribution shifted outward and upward, so that by June of the next year the highest aphid densities occurred on current and 1‐year‐old needles on branches near the top of the tree. 4 The aphid distribution was re‐set each year during July, at the time when the nutrient quality of the host was in decline and E. abietinum populations were decreasing. Aphid densities decreased less on 3–4‐year‐old needles than on current and 1‐year‐old needles, suggesting that older needles were a superior food resource at this time of year and in the autumn. However, other factors, such as higher temperatures in the upper canopy during the summer or differential mortality caused by natural enemies, could also have contributed to the change in distribution. 5 The outward and upward shift in the aphid distribution over the winter period provided no evidence that aphids at positions lower and deeper in the canopy were better insulated from freezing temperatures and had higher over‐winter survival rates. Mean air temperatures at the top and bottom of the canopy during the winter were also found to differ by only 0.1–0.2 °C. 6 The percentage of the total aphids per tree that occurred on current or 1‐year‐old needles varied widely between seasons and between sites. Consequently, sampling programmes designed to estimate total population numbers of E. abietinum have little option but to sample needles throughout the canopy, and at regular intervals during the period when the aphid is abundant.     

Metabolism of tritiated and deuterated gibberellins A1, A4 and A9 in Sitka spruce (Picea sitchensis) shoots during the period of cone-bud differentiation

A mixture of tritiated and deuterated gibberellins (GAs) was injected into elongating shoots of Sitka spruce [ Picea sitchensis (Bong.) Carr.] grafts grown under environmental conditions that were either inductive (heat and drought, HD) or non-inductive (cool and wet, CW) for flowering. The metabolites were purified by high performance liquid chromatography (HPLC), detected by liquid scintillation counting of aliquots of collected fractions and identified by gas chromatography–mass spectrometry (GC-MS). Deuterated GA₉ was converted to deuterated GA₄, deuterated GA₃₄, and deuterated GA₁ in both treatments. Deuterated GA₄ was metabolized to deuterated GA₃₄ and deuterated GA₁ in the CW material, but only deuterated GA₁ was detected in the HD material. The amount of detected metabolites was higher in the HD material, caused by a higher rate of metabolism and/or smaller losses of the metabolites during sample purification. GA₁ was converted to a polar unidentified metabolite in both treatments, but to a higher degree in the CW treatment.     

Growth of coniferous trees exposed to SO2 and O3 using an open-air fumigation system

Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.) and Sitka spruce (Picea sitchensis Bong. Carr.) were planted as 2-year-old seedlings in an open-air fumigation facility at Liphook in southern England in March 1985. The soil was a humoferric podzol of pH 4. SO₂ fumigation began in May 1987 and continued until December 1990. Long-term mean SO₂ concentrations were 4,13 and 22 nmol mo^?1. Three plots, one at each SO₂ level, were also exposed to O₃ at an average of 1–3.times the ambient level. O₃ fumigation ran from March to December 1988, May to December 1989 and February to December 1990. Each species reacted differently to treatment. Scots pine showed no growth response to either pollutant, although other work on the site demonstrated a number of deleterious effects of SO₂ on this species, including increased leaf loss and foliar injury. Stem basal diameter growth of Norway spruce was depressed in SO₂-treated plots. In contrast, extension growth of shoots of Sitka spruce increased in SO₂-treated plots, in apparent response to codeposition of NH₃-N. However, diameter growth of Sitka spruce main stems did not increase. No effects of O₃ on growth were recorded for any species.     

Growth response of branches of Picea sitchensis to four years exposure to elevated atmospheric carbon dioxide concentration

Branch bags were used to expose branches on mature Sitka spruce trees to either ambient [CO₂] (A) or elevated [CO₂] (E) for 4 yr. This paper reports the effects of this treatment on the growth, development and phenology of the branches, including shoot expansion, shoot numbers, needle dimensions, needle numbers and stomatal density. The effect of elevated [CO₂] on the relationship between leaf area and sapwood area was investigated. Exposure to elevated [CO₂] doubled photosynthetic rates in current-year shoots and, despite some down-regulation, 1-yr-old E shoots also had higher rates of photosynthesis than their A counterparts. Thus, the amount of assimilate fixed by E branches was substantially more than that fixed by A branches; however, this increase in the local production of assimilate did not lead to an increase in non-structural carbohydrate or stimulate growth or meristematic activity within the E branches. There was a very consistent relationship between leaf area and stem cross-sectional area that was not influenced by [CO₂]. However, unbagged branches had thicker stems than bagged branches, resulting in a slightly lower ratio of leaf area to cross-sectional area. The implications of the results for the modelling of growth and allocation and the potential utility of the branch bag technique are discussed.     

The role of extracellular free-calcium gradients in gravitropic signalling in maize roots

Gravitropism in roots has been proposed to depend on a downward redistribution of calcium across the root cap. However, because of the many calcium-binding sites in the apoplast, redistribution might not result in a physiologically effective change in the apoplasmic calcium activity. To test whether there is such a change, we measured the effect of gravistimulation on the calcium activity of statocyte cell walls with calcium-specific microelectrodes. Such a measurement must be made on a tissue with gravity sensing cells at the surface. To obtain such a tissue, decapped maize roots (Zea mays L. cv. Golden Cross Bantam) were grown for 31 h to regenerate gravitropic sensitivity, but not root caps. The calcium activity in the apoplasm surrounding the gravity-sensing cells could then be measured. The initial pCa was 2.60 ± 0.28 (approx 2.5 mM). The calcium activity on the upper side of the root tip remained constant for 10 min after gravistimulation, then decreased 1.7-fold. On the lower side, after a similar lag the calcium activity increased 1.6-fold. Control roots, which were decapped but measured before recovering gravisensitivity (19 h), showed no change in calcium activity. To test whether this gradient is necessary for gravitropic curvature, we eliminated the calcium activity gradient during gravitropism by applying a mobile calcium-binding site (di-nitro-BAPTA; 1,2-bis(2-amino-5-nitro-phenoxy)ethane-N,N,N,N-tetraacetic acid) to the root cap; this treatment eliminated gravicurvature. A calcium gradient may be formed by proton-induced calcium desorption if there is a proton gradient. Preventing the formation of apoplastic pH gradients, using 10 and 50 mM 2-(N-morpholino)ethanesulfonic acid (Mes) buffer or 10 mM fusicoccin to stimulate proton excretion maximally, did not inhibit curvature; therefore the calcium gradient is not a secondary effect of a proton gradient. We have found a distinct and rapid differential in the apoplasmic calcium activity between the upper and lower sides of gravistimulated maize root tips which is necessary for gravitropism.Abbreviations BAPTA 1,2-bis(2-aminophenoxy)ethane-N,N,N,N-tetraacetic acid - FC fusicoccin - Mes 2-(N-morpholino)ethanesulfonic acid The authors thank Phyllis Woolwine for drawing Fig. 1, Dr. Sarbjit Virk for assistance with total calcium measurements, Dr. Paul Sampson for statistical advice, and Michael Newton for developing the EM algorithm to analyze the time-series data. This work was supported by NASA grant NAGW-1394 and by a NASA Research Associateship to T.B. through NASA grant NAGW-70.     

Detection and identification of gibberellins in Sitka spruce (Picea sitchensis) of different ages and coning ability by bioassay, radioimmunoassay and gas chromatography – mass spectrometry

Gibberellins Al (GA₁), GA₃, GA₄, GA₉, and after enzymatic hydrolysis of GA-conjugate-like fractions, GA₉ and GA₁₅, were identified in shoots of Sitka spruce [ Picea sitchensis (Bong.) Carr.] of different ages by combined gas chromatography-mass spectrometry (GC-MS). The purification and separation of the GAs involved the use of reverse phase and normal phase high performance liquid chromatography (HPLC). The Tan-ginbozu dwarf rice bioassay and binding to antibodies raised against GA₁, GA₄ and GA₉ were used for detection of GA-like substances. The qualitative differences between the three ages of plant material were the presence of GA₃ and GA₁ in the 48-year-old material and the absence of detectable amounts of GA₄ in the same material. This indicates a difference in GA metabolism which may reflect the difference in ability to form reproductive buds.