Physiological Characteristics and Carbohydrate Contents of Spring-lifted Picea glauca Bareroot Seedlings Following Low-temperature Storage

This study examined the effects of low-temperature storage of white spruce [ Picea glauca (Moench) Voss] bareroot seedlings to determine whether the time between lifting and planting of spring-lifted seedlings could be extended. Seedlings were lifted from the nursery beds on May 4, 1994, and stored at- 2C (frozen storage) and 4C (cold storage) for 3, 5 and 7 weeks. Frozen storage of spring-lifted seedlings resulted in an increase in sugar levels in roots and needles that progressed with storage duration. Seedlings stored in cold storage maintained a relatively constant sugar content. Needle starch content decreased with storage duration in both frozen and cold storage. In the roots of cold-stored seedlings, starch content remained relatively constant during storage; however, in the frozen-stored seedlings, root starch levels sharply declined during the initial 3 weeks of storage. The levels of total non-structural carbohydrates (starch and sugars) decreased in both types of storage in needles, but not in roots. However, the decrease was more pronounced in the cold-stored than in the frozen-stored seedlings. Gas exchange, root growth potential and number of days to bud break were similar in frozen- and cold-stored seedlings planted in the greenhouse. However, following planting in the forest, cold-stored seedlings flushed buds earlier than did frozen-stored seedlings. The results indicate that tree nurseries could consider frozen storage of spring-lifted white spruce seedlings to facilitate lifting and planting schedules.     

Development of a molecular test to determine the vitality status of Norway spruce (Picea abies) seedlings during frozen storage

In boreal forest regions, a great portion of forest tree seedlings are stored indoors in late autumn to prevent seedlings from outdoor winter damage. For seedlings to be able to survive in storage it is crucial that they store well and can cope with the dark and cold storage environment. The aim of this study was to search for genes that can determine the vitality status of Norway spruce (Picea abies (L.) Karst.) seedlings during frozen storage. Furthermore, the sensitivity of the ColdNSure? test, a gene activity test that predicts storability was assessed. The storability of seedlings was tested biweekly by evaluating damage with the gene activity test and the electrolyte leakage test after freezing seedlings to ?25?°C (the SEL_diff-25 method). In parallel, seedlings were frozen stored at ?3?°C. According to both methods, seedlings were considered storable from week 41. This also corresponded to the post storage results determined at the end of the storage period. In order to identify vitality indicators, Next Generation Sequencing (NGS) was performed on bud samples collected during storage. Comparing physiological post storage data to gene analysis data revealed numerous vitality related genes. To validate the results, a second trial was performed. In this trial, gene activity was better in predicting seedling storability than the conventional freezing test; this indicates a high sensitivity level of this molecular assay. For multiple indicators a clear switch between damaged and vital seedlings was observed. A collection of indicators will be used in the future development of a commercial vitality test.     

沙地沙棘苗冷藏造林技术研究

为了提高半干旱区沙漠化土地的造林成活率与保存率,文章对一年生沙棘苗进行了冷藏处理和造林抚育试验。试验发现:冷藏可以延长苗木的保存期,使造林得以在春季干旱多风季节之后进行,避开了干旱与大风对苗木的危害,有效地提高造林的成活率,同时也降低了造林与抚育的成本。与常规造林相比,冷藏苗造林可以节省约50%左右的费用。试验还发现沙棘苗木在冷藏过程中,适度的温度控制以及冷藏后与造林前的常态恢复训练与苗木冷藏处理后质量的好坏有着密切的联系。训练过程中要注意保持一定的湿度,训练应该选择在阴天或阴凉处进行,避免光线直射。人工开沟深坑造林技术也是提高冷藏苗造林成活率的重要技术之一。     

Effectiveness of freezer storage in fulfilling the chilling requirement of fall-lifted ponderosa pine seedlings

The degree to which freezer storage fulfilled the chilling requirement of ponderosa pine (Pinus ponderosa Dougl. ex Laws.) seedlings of two sources was determined by monitoring their development after potting or planting. The seedlings were lifted in September, October, November, or March and subjected to storage before outplanting. The fulfillment of chilling was assessed by measuring days to budbreak, cumulative percentage of seedlings flushing, foliated shoot length, and rate of bud abortion. The effect of freezer storage depended on stage of seedling development at lifting, length of storage, and seed source. Storage did not totally replace winter conditions, especially for seedlings lifted in September and October. Those from a high-elevation seed source flushed sooner than those from a low-elevation source. Delayed budbreak after planting of early lifted seedlings from the high-elevation source disappeared in the second year, but those from the low-elevation source continued to show effects. Seedlings lifted and stored in November had patterns of budbreak that were similar to those of seedlings that had overwintered in beds.     

First-year growth response of cold-stored,nursery-grown aspen planting stock

This research examined the first year growth characteristics of cold stored and transplanted nursery-produced aspen (Populus tremuloides) seedlings (container and bareroot (BR)) and compared it to the growth of seedlings that had not been transplanted (established from germinants in the field) and therefore had an unrestricted root system (UR). Prior to planting, nursery-produced seedlings were placed in cold storage (−3°C) and root growth potential (RGP) and total non-structural carbohydrate (TNC) root reserves were tested at 0, 10, 75 and after 150 (container) and 190 days (BR) of storage. Both container and BR stock had much lower root to shoot ratios (RSRs) and root carbohydrate reserves compared to UR seedlings after 170 days. During storage, root reserves in container stock declined faster than in the BR and UR seedlings. RGP in all nursery stock was the highest after 75 days of storage, while longer storage resulted in shoot dieback and reduced root growth. After the first growing season, UR seedlings were one tenth the size of the nursery stock; however, in the second growing season they had no stem dieback and grew twice the height and stem diameter. The higher RSRs and root reserves in the UR seedlings was likely caused by early bud set in its first year of growth. This suggests that inducing bud set earlier in the growing regime might allow seedlings to increase root mass and carbohydrate reserves.     

刺槐裸根苗冷藏处理造林试验初报

通过对刺槐冷藏苗和非冷藏苗开展造林试验,观测和分析造林当年和次年苗木成活率、萌芽成枝力、新梢生长量、基径和苗高,研究了刺槐经冷藏处理的裸根苗造林效果。结果表明:刺槐苗木经冷藏处理后造林,能非常显著地提高成活率、萌芽成枝力、新梢生长量、基径和苗高等指标。     

Temporal variations in cold sensitivity of root growth in cold-stored white spruce seedlings

We examined effects of soil temperature on the number of roots produced by white spruce (Picea glauca (Moench.) Voss) seedlings during the first month of growth following 0-30 weeks of storage in darkness at -2 degrees C. After storage, seedlings were planted in pots and placed in a controlled-environment chamber with a constant air temperature of 11 degrees C and a 16-h photoperiod. Water baths were used to keep soil temperature at 3, 7 or 11 degrees C. The number of long roots (> 10 mm) produced was strongly dependent on soil temperature. At soil temperatures of 3 or 7 degrees C, the number of long roots produced was only 11 to 30% that at 11 degrees C. Seedlings that had been stored for 14 weeks and then planted in soil at 11 degrees C produced the greatest number of long roots. For seedlings planted in soil at 11 degrees C, the number of long roots increased with time of storage up to 14-18 weeks and then declined progressively with length of storage. No increase in number of long roots with length of storage up to 18 weeks was evident in seedlings planted in soil at 3 or 7 degrees C. The maximum number of short roots (5-10 mm) was observed in seedlings that had been stored for 17 weeks and then planted in soil at 7 or 11 degrees C.     

Effects of Previous High N Addition on Nutrient Conditions in Above-ground Biomass of a Picea abies Stand in Sweden

The effect of different thawing procedures on seedling quality in Norway spruce (Picea abies) was evaluated. Freezer-stored seedlings were thawed rapidly for 20 h by immersion in water with an initial water temperature of 8°C or thawed more slowly by gradually increasing the temperature in storage over a period of 8 weeks. Seedlings from these treatments were also compared with seedlings thawed rapidly overnight at 15°C. Frost tolerance, carbohydrate content and the time of bud break were used as indicators of the vitality of the seedlings. Seedlings thawed rapidly in water or air showed significantly better frost tolerance after storage than slowly thawed seedlings. The contents of sucrose and raffinose in seedlings thawed rapidly were also significantly higher than in seedlings thawed more slowly. Bud break occurred later in seedlings thawed rapidly than in slowly thawed seedlings. Rapid thawing in water may be a good method to ensure the delivery of high-quality thawed seedlings throughout the planting season.     

Cold hardiness and transplant response of Juglans nigra seedlings subjected to alternative storage regimes

? Effects of overwinter storage regimes on seedling cold hardiness and physiological vigor are relatively unexplored, particularly for temperate deciduous forest tree species.

? We evaluated influence of storage duration (0, 66, 119, or 175 d) on electrolyte leakage of stem and root collar tissues following exposure to a series of freeze-test temperatures in black walnut (Juglans nigra L.) seedlings sampled from cold (3 °C) or freezer (?2 °C) storage. Seedlings were subsequently transplanted into a controlled growth chamber environment for two months.

? Regardless of storage temperature, mean LT₅₀ was lowest for seedlings stored for 66 d (≤ ?34 °C) and increased dramatically after 119 d (≥ ?13 °C).

? Root collar tissue had lower LT₅₀ than stem tissue after 119 d for cold-stored seedlings, reflecting importance of evaluative tissue type. Days to bud break shortened with increasing storage duration up to 119 d and stabilized thereafter for both storage regimes. Root growth potential was maximized after 119 d of storage, and subsequently declined for cold-stored seedlings. Height growth increased following storage, regardless of duration.

? To promote stress resistance and transplant growth response, we recommend that black walnut seedlings from this genetic source be outplanted after approximately 66–119 d of storage.

     

凹叶厚朴种子保存方法及幼苗生长规律

对凹叶厚朴的种子保存方式及相应的播种苗的发芽情况、幼苗生长规律进行统计分析。结果表明:冷藏处理的凹叶厚朴种子发芽慢、发芽持续时间长;播种苗株高生长呈"S"型的慢—快—慢的规律,地径与叶幅生长表现出快—慢—快—慢的规律;株高、地径、叶幅三者之间的生长呈极显著正相关;种子经沙藏的凹叶厚朴发芽时间、出苗速度及发芽率均优于冷藏处理,而且,沙藏处理的苗高、地径、叶幅的累积生长量相应地大于冷藏处理。     

Use of short-day treatment in the production of Norway spruce mini-plug seedlings under plant factory conditions

Mini-plug transplant seedlings of Norway spruce have been cultivated in closed growth systems, so-called plant factories, for few years. The aim of the experiment was to define a short-day treatment (SD) that harden seedlings to sustain 3 months of cold storage, but does not have adverse effects on growth, morphology, and vitality. The seedlings were subjected to one of the following treatments: (1) 12?h photoperiod + 3 weeks duration; (2) 8?h photoperiod + 3?wk duration; (3) 12?h photoperiod + 5?wk duration; and (4) 8?h photoperiod + 5?wk SD. All the SD treatments yielded healthy seedlings that grew well after the cold storage. The frost hardiness of the seedlings improved when the photoperiod was reduced from 12 to 8?h, and when the SD duration was increased from 3 weeks to 5 weeks, but reducing the photoperiod from 12?h to 8?h caused growth reductions. The root and shoot regrowth after cold storage was highest in seedlings that had received 12?h photoperiod and 5?wk duration. However, 12?h photoperiod and 3?wk duration may be an adequate practice for nurseries that treat multiple crops in their SD facilities.     

Effect of nursery storage and site preparation techniques on field performance of high-elevation Pinus contorta seedlings

After five years of growth at high-elevations (∼3000 m) in Utah, container lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) seedlings survived well (80–95%) and grew to similar heights regardless of nursery storage method and site preparation technique. Seedlings received one of three storage treatments: (1) spring-sown in the nursery, overwintered in cooler storage and outplanted in July; (2) spring-sown, overwintered in freezer storage, and outplanted in July; or (3) winter-sown, no storage, and hot-planted in late August. We outplanted seedlings at two locations that were clearcut and had received two treatments of surface organic matter (coarse wood, logging slash, and forest floor) removal: surface organic matter (OM) piled with a bulldozer and burned or surface OM remaining in situ. Compared to adjacent uncut stands, both site preparation treatments increased total soil bulk density, but retaining surface OM in situ maintained soil OM, carbon, and nitrogen levels. After one growing season, seedlings planted where surface OM had been bulldozed were taller and had more biomass, although survival was similar (≥96%) across site preparation treatments. The height growth advantage disappeared after five growing seasons and although overall survival was good, survival was highest where site preparation involved removal of surface OM and freezer-stored seedlings were planted. Total non-structural carbohydrates tended to be higher in roots than in shoots and were also higher in hot-planted seedlings than in stored seedlings. Our results indicate that nursery and forest managers have several options for successful nursery production and outplanting of container lodgepole pine seedlings in the central Rocky Mountains. Using hot-planted seedlings allows for a faster turnaround time (from seed to plantable seedling) and maintaining surface OM may be a cost-effective alternative to dozer piling and burning.     

Carbohydrate reserve accumulation and depletion in Engelmann spruce (Picea engelmannii Parry): effects of cold storage and pre-storage CO(2) enrichment

The effects of pre-storage CO(2) enrichment on growth, non-structural carbohydrates and post-storage root growth potential of Engelmann spruce (Picea engelmannii Parry) seedlings were studied. Seedlings were grown from seed for 202 days in growth chambers with ambient (340 micro l l(-1)) or CO(2) enriched (1000 micro l l(-1)) air. Some seedlings were transferred between CO(2) treatments at 60 and 120 days. Photoperiod was reduced at 100 days to induce bud set and temperature was reduced at 180 days to promote frost hardiness development for storage at -5 degrees C for 2 or 4 months. Stored seedlings were planted in a growth chamber after thawing for one week at +5 degrees C. At 80, 120, 140 and 202 days, and at each planting time after storage, seedlings were harvested for growth measurements and analysis of starch and soluble sugar concentrations. Planted seedlings were assessed for bud break every two days and new roots > 5 mm long were counted after four weeks. Carbon dioxide enrichment increased root collar diameter and almost doubled seedling biomass, with the most obvious effects occurring after bud set. Stem height was affected only slightly and shoot/root ratios were not affected at all. Carbon dioxide enrichment increased the rate of reserve carbohydrate accumulation, but did not influence the final concentration attained before storage (accounting for 32% of seedling dry weight). Needles were the major storage organ for soluble sugars, whereas roots were the major storage organ for starch. Soluble sugars were not strongly affected by two or four months of storage, but starch was reduced by more than 50% in all plant parts. None of the CO(2) treatments had an impact on bud break or root growth potential.     

Evaluating methods for storability assessment and determination of vitality status of container grown Norway spruce transplants after frozen storage

ABSTRACT

Autumn sown small seedlings for later transplanting into large containers have been introduced in Swedish forest tree nurseries. Containerized transplants of Norway spruce (Picea abies (L.) Karst.) from three Swedish nurseries were frozen stored during the autumn of 2014 to find out storability and post-storage vitality. Seedling storability was determined by measuring electrolyte leakage after freezing shoots to ?25°C (SE L _diff?25), by measurements of dry matter content (DMC) of seedling shoots and by the commercial molecular test ColdNSure?. Vitality of seedlings after storage was determined by measuring the leakage of electrolytes from shoots (SEL), and seedlings were also tested in regrowth tests. All three methods for storability assessment gave similar predictions, except in one case where DMC showed “not storable” for successfully stored seedlings. Our results indicated that young transplants can be successfully short term stored before reaching the target levels for safe long-term storage of conventional seedlings. Early storage of young transplants resulted in low post-storage survival and vitality expressed as root growth capacity and shoot electrolyte leakage (SEL). A prolonged duration in storage generally resulted in lower survival as well as lower root growth capacity and higher levels of SEL, especially for seedlings stored at earlier dates.     

Effects of cold storage and water stress on water relations and gas exchange of white spruce (Picea glauca) seedlings

To determine the effects of lifting time and storage on water-stress resistance of nursery-grown white spruce (Picea glauca (Moench) Voss) seedlings, we compared gas exchange, water relations and mortality of 3-year-old seedlings lifted in October 1991 and stored at -2 degrees C for 3 months with seedlings lifted in January 1992. The seedlings were placed in nutrient solution and subjected to -1.1 or -2.7 MPa water stress induced by polyethylene glycol 3350 for 9 days. Water stress, but not lifting time, had a significant effect on seedling net assimilation, symplastic volume and turgor loss point. In a second experiment, seedlings lifted in October 1991 were stored at -2 degrees C for 7 months and compared with seedlings lifted in May 1992. The seedlings were planted in pots, and their gas exchange and water relation parameters measured in response to gradual water stress. The results suggest that prolonged cold storage retards photosynthetic recovery of seedlings after planting. Higher rates of net assimilation in seedlings lifted in May were not directly related to their water status. Nonstomatal limitations were the primary factor influencing photosynthetic rate. We conclude that the inferior ability of cold-stored seedlings to tolerate water stress was due to poor osmotic adjustment and a lag in recovery of photosynthesis.     

种子贮藏和播种方式对红椆发芽及苗木生长的影响

以红椆种子为试验材料,进行贮藏和播种方式对红椆种子发芽和苗木生长的影响试验。结果表明:不同贮藏方式对红椆种子发芽率有极显著影响;不同播种方式对红椆种子发芽率和苗木地径生长无显著影响,但对苗木成活率和苗木高生长影响极显著。     

Storability measures of Norway spruce and Scots pine seedlings and assessment of post-storage vitality by measuring shoot electrolyte leakage

As indoor frozen storage is increasing in forest tree nurseries it is important to have accurate methods for assessing seedling storability in autumn and methods to determine post-storage vitality. Storability of spruce (Picea abies (L.) Karst.) and pine (Pinus sylvestris L.) seedlings can be based on determination of dry matter content (DMC) of seedling shoots or by freezing shoots at –25°C and thereafter measure electrolyte leakage (SEL_diff–25). To compare these two methods we stored 1-year-old spruce and pine seedlings at different occasions during the autumn. To test if leakage of electrolytes from shoots (SEL) could indicate deteriorated vitality, we measured SEL at the end of storage. After storage seedling viability was determined in a three-week growth test, measuring shoot and root growth capacity (RGC). Determination of freezing tolerance (SEL_diff–25) before storage had a better ability to predict the outcome of storage compared to the DMC test. Measuring SEL at the end of the frozen storage period accurately indicated seedling vitality. Seedlings with SEL of 0–5% had a high survival rate whereas SEL over 10% indicated low survival and growth capacity after storage. The SEL method has a potential to become a screening test for identifying batches of seedlings that have been damaged during storage in the nursery.     

东北红豆杉有性繁殖播种育苗

东北红豆杉,又名紫杉,是第三纪孑遗的珍贵树种。红豆杉资源的保存和种苗的快速繁育,是解决紫杉醇用材林的基础,大面积营造红豆杉人工林是解决紫杉醇原料的关键。用红豆杉种子繁殖苗木时,要注意种子的储存方式,要沙种混藏或控温处理,这对越冬后出芽和打破休眠习性,具有很好的效果。播种前要搓伤种皮、温水浸种、药剂素处理。     

Effects of different overwinter storage regimes on shoot growth and net photosynthetic capacity in Pinus Sylvestris Seedlings

Seedlings of Pinus sylvestris were cold‐stored for three or six months at ‐4°C or 2°C or overwintered outdoors. Dry weight development and net photosynthetic capacity were then measured during a 60‐day cultivation period in a controlled environment. In all storage regimes the longer storage period gave a faster growth initiation. Photosynthetic recovery was faster for seedlings stored at 2°C than at ‐4°C, due to better recovery of stomatal conductance. The results suggest that there is little difference in seedling development between storage temperatures of ‐4°C and 2°C whereas outdoor storage might cause certain negative effects on subsequent growth of seedlings. This result is discussed with regard to the present winter climate.     

Bareroot versus container stocktypes: a performance comparison

This review examines the published work on bareroot and container stocktypes in forest restoration programs. The objective was to define overall trends between these two stocktypes and describe what they mean in terms of available information on their nursery and field performance. Stock quality assessments show bareroot seedlings have larger shoot systems because they are typically grown at lower densities, and in many instances longer timeframes, than container seedlings. Container systems typically produce seedlings having a lower shoot to root ratio and a greater root growth potential, conferring greater drought avoidance potential. However, assessments of stress resistance and nutrition found no conclusive evidence that either stocktype has a performance advantage, other than the container plug acting as a source of water and nutrient storage available for outplanting performance. Bareroot seedlings are more sensitive to handling practices of lifting, storage, transport and planting and these practices can negatively affect their performance. Container seedlings can have a higher level of field survival which is related, in part, to their greater drought avoidance potential, thereby overcoming planting stress. Bareroot and container seedlings have comparable survival rates on sites with minimal planting stress. Once seedlings are established, bareroot and container seedlings can have comparable field performance. In many instances where plant competition is the main limiting site variable, larger sized bareroot and container stocktypes have the best chance for successful stand establishment. The lack of a natural root form and root distribution for both stocktypes is a debated mechanical stability issue, though risks of windthrow have not been consistently demonstrated for either stocktype.