Digging for Britain - Netflix
The BBC Two series is presented by Professor Alice Roberts and archaeologist Matt Williams as they present the year's most outstanding archaeology.
Status: To Be Determined
Runtime: 60 minutes
Digging for Britain - Transplanting - Netflix
For botanical organ transplant, see Grafting In agriculture and gardening, transplanting or replanting is the technique of moving a plant from one location to another. Most often this takes the form of starting a plant from seed in optimal conditions, such as in a greenhouse or protected nursery bed, then replanting it in another, usually outdoor, growing location. This is common in market gardening and truck farming, where setting out or planting out are synonymous with transplanting. In the horticulture of some ornamental plants, transplants are used infrequently and carefully because they carry with them a significant risk of killing the plant. Transplanting has a variety of applications, including: Extending the growing season by starting plants indoors, before outdoor conditions are favorable; Protecting young plants from diseases and pests until they are sufficiently established; Avoiding germination problems by setting out seedlings instead of direct seeding. Different species and varieties react differently to transplanting; for some, it is not recommended. In all cases, avoiding transplant shock—the stress or damage received in the process—is the principal concern. Plants raised in protected conditions usually need a period of acclimatization, known as hardening off (see also frost hardiness). Also, root disturbance should be minimized. The stage of growth at which transplanting takes place, the weather conditions during transplanting, and treatment immediately after transplanting are other important factors.
Digging for Britain - Field storage - Netflix
As advocated by Coates et al. (1994), thawed planting stock taken to the field should optimally be kept cool at 1°C to 2°C in relative humidities over 90% (Ronco 1972a). For a few days, storage temperatures around 4.5°C and humidities about 50% can be tolerated. Binder and Fielder (1988) recommended that boxed seedlings retrieved from cold storage should not be exposed to temperatures above 10°C. Refrigerator vans commonly used for transportation and on-site storage normally ‘maintain seedlings at 2°C to 4°C (Mitchell et al. 1980). Ronco (1972a, b) cautioned against using dry ice (solid carbon dioxide) to cool seedlings; he claimed that respiration and water transport in seedlings are disrupted by high concentrations of gaseous carbon dioxide. Coniferous planting stock is often held in frozen storage, mostly at -2°C, for extended periods and then cool-stored (+2°C) to thaw the root plug prior to outplanting. Thawing is necessary if frozen seedlings cannot be separated from one another and has been advocated by some in order to avoid possible loss of contact between plug and soil with shrinkage of the plug with melting of ice in the plug. Physiological activity is also greater under cool rather than frozen storage, but seedlings of interior spruce and Engelmann spruce that were planted while still frozen had only brief and transient physiological effects, including xylem water potential, (Camm et al. 1995, Silem and Guy 1998). After 1 growing season, growth parameters did not differ between seedlings planted frozen and those planted thawed. Studies of storage and planting practices have generally focussed on the effects of duration of frozen storage and the effects of subsequent cool storage (e.g., Ritchie et al. 1985, Chomba et al. 1993, Harper and Camm 1993). Reviews of colds storage techniques have paid little attention to the thawing process (Camm et al. 1994), or have merely noted that the rate of thawing is unlikely to cause damage (McKay 1997). Kooistra and Bakker (2002) noted several lines of evidence suggesting that cool storage can have negative effects on seedling health. The rate of respiration is faster during cool storage than in frozen storage, so depleting carbohydrate reserves more rapidly. Certainly in the absence of light during cool storage, and to an indeterminate extent if seedlings are exposed to light (unusual), carbohydrate reserves are depleted (Wang and Zwiacek 1999). As well, Silem and Guy (1998), for instance, found that interior spruce seedlings had significantly lower total carbohydrate reserves if stored for 2 weeks at 2°C than if thawed rapidly for 24 hours at 15°C. Seedlings can rapidly lose cold hardiness in cool storage through increased respiration and consumption of intracellular sugars that function as cryoprotectants (Ogren 1997). Also, depletion of carbohydrate reserves impairs the ability of seedlings to make root growth. Finally, storage moulds are much more of a problem during cool than frozen storage. Kooistra and Bakker (2002), therefore, tested the hypothesis that such thawing is unnecessary. Seedlings of 3 species including interior spruce were planted with frozen root plugs (frozen seedlings) and with thawed root plugs (thawed seedlings). Thawed root plugs warmed to soil temperature in about 20 minutes; frozen root plugs took about 2 hours, ice in the plug having to melt before the temperature could rise above zero. Size of root plug influenced thawing time. It should be noted that these outplantings were into quite warm soil by boreal standards, and seedlings with frozen plugs might fare differently if outplanted into soil at temperatures more typical of planting sites in spring and at high elevations. Variable fluorescence did not differ between thawed and frozen seedlings. Bud break was no faster among thawed interior spruce seedlings than among frozen. Field performance did not differ between thawed and frozen seedlings.
Digging for Britain - References - Netflix