Cold-requiring plants

Figure 1. Effect of gibberellin on flowering in carrot (variety Early French Forcing), a cold-requiring plant (24)...

In cold-requiring plants an increased level of cytokinins is usually found in response to a chilling treatment [see 5, 10, 14]. A similar situation was reported for buds and shoots of Firms and Douglas fir during transition to reproductive growth [13, 17, 22]. In Douglas fir the increase was mostly in an iP-like fraction and was correlated with enhanced female flowering [13]. 

Induction of Flower Formation. In the case of long day plants and a number of cold-requiring plants gibberellins can induce the formation of flowers under conditions under which this does not normally occur. We shall discuss this phenomenon later (page 304). 

Most cold-dependent plants also possess a long-day requirement. The gibberellin treatment of these plants was usually conducted under long-day conditions, so that only the temperature-controlled block to flower formation was present. If the treatment was given under short-day conditions, only stem elongation was obtained it is evidently difficult to overcome the simultaneous presence of two blocks to flower formation. 

Michniewicz M, Lang A (1962) Effect of nine different gibberellins on stem elongation and flower formation in cold requiring and photoperiodic plants grown under non-inductive conditions. Planta (Berl) 58 549-563 Milborrow BV (1974) The chemistry and physiology of abscisic acid. Annu Rev Plant Physiol 25 259-307... 

The first Base-Load LNG-Plantwas put into operation in Algeria in 1964. From today s point of view, the early plants disposed of a low liquefaction capacity of below one million tons of LNG per year (< 1.0 mtpa LNG). The cold required for the liquefaction was usually generated in a series arrangement of pure component refrigeration cycles (pure component cascade) or in one single mixed refrigerant cycle. 

If after cold treatment plants still require long days then usually treatment with gibberellins can only substitute for the effect of cold and not for that of the long day. 

The impact of cold GR-S was quite pronounced. The U.S. government edicted that all of the emulsion SBR plants switch to the cold process. This required addition of refrigeration capacity in these plants as well as other significant changes, such as insulation of reactors, improved vacuum to reduce oxygen that retards polymerization, and the heating of latex in blowdown tanks to aid in the disengagement of butadiene when transferred to the flash tanks. 

Weather data for a number of years should be assembled for each community being studied. Particular attention should be given to such natural disasters as hurricanes, earthquakes, and floods, which often can be predicted from meteorological data. In certain locations these catastrophic events must be assumed to be probable and this increases construction costs. E.xtremely cold weather often hampers process plant operation and requires special construction features to protect equipment from freezing. Predominantly warm weather permits cheaper construction but may also reduce the efllcicncy of the labor force. 

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