ALBERT

Description: 1. Under normal English storage conditions, the heat production of mature potatoes drops rapidly from a value of probably about 150 b.th.u./ton/hr. immediately after harvest to about 30–50 b.th.u./ton/hr. Sprouting is accompanied by an increase in the rate of heat production. The initial heat production of immature potatoes may be of the order of 250 b.th.u./ton/hr.2. As a result of the production of heat, the temperatures in stacks of potatoes will tend to rise to levels above that of the outside air which are just sufficient to cause the convection and conduction necessary to remove the metabolic heat as fast as it is produced.3. The difference in temperature between the potatoes and the ambient air is a function of the heat production of the potatoes and of the height of the stack, and is practically independent of its other dimensions if these exceed twice the height. Under average conditions during the middle of the storage season, and for heights of storage of from about 6 to 12 ft. it may be taken as a rough practical guide that the average and maximum temperatures of the potatoes will tend to exceed the average temperature of the store air by about 2/3 and 1° F. respectively for every foot of height.4. Overheating is possible at both the beginning and end of the storage season, when heat production is high and the outside temperatures also possibly high. In general it is safe to store unventilated potatoes to a height of about 6 ft. if they are mature, though if they are harvested with a great deal of earth late storage should not be attempted. If there is no intention of storing late, and the potatoes are fairly clean, storage to aheight of 12 ft. may be permissible. Immature potatoes should not be stored to a height of more than 3 ft.

Description: SUMMARYAdapting in vitro transgenic carrots to soil is the most crucial step preceding the field investigation of transgenic carrots. A low proportion of plants, around 0·20, acclimatize to soil (Hardegger & Sturm 1998) and thus prohibit the generation of high-expression carrot lines. In the present paper, a protocol for an efficient soil transfer is presented and the impact of carrot cultivar, soil substrate, tissue culture, and transformation process on transfer process is analysed. Somatic embryo germinants of Daucus carota cv. Rote Riesen 2 and Lobbericher Gelbe Futtermoehre showed a tremendous survival proportion – up to 1·00 – when transferred to their optimal soil substrate: sandy and loamy soil, with low content of macro and micro elements and a pH of 5·8. By optimizing the conditions described here, the proportion of soil acclimatized transgenic carrot plants of D. carota Lobbericher Gelbe Futtermoehre was increased from 0·1 to 0·87, and for the cultivar Rote Riesen from 0·09 to 0·67.

Description: Permanent buildings of a variety of designs have been in widespread use for many years as potato stores on the Continent of Europe and in the United States of America. (For a summary of recent literature, with references, see Rose & Cook, 1949.) There are examples of buildings being used as potato stores in this country (e.g. Keith, 1941), but the bulk of the crop is stored in clamps. Because the climates of the U.S.A. and the Continent of Europe differ markedly from that of Great Britain, it is not possible to use the types of store developed in those regions as models for British stores. Over much North America and the Continent of Europe the stores are designed to withstand severe winter frosts, and the main problem is to keep the temperature of the tubers high enough to prevent freezing, the metabolic heat being readily removed if necessary by a small amount of controlled ventilation. Under British conditions the mean daily temperature for most of the storage season, above the optimum for potato storage (40·42° F.), and therefore the main problem is that of keeping the tubers cool. This could, of course, be achieved by using a cold store, but cold storage is considered too expensive. To design a store, information is required about the temperatures attained by stacks of potatoes at different times of the year, the effectiveness ventilation in controlling the temperature, the relation of temperature in different parts of the stack to dimensions of the stack, and to the insulation both of the bin and of the building. To obtain this data a programme of work was initiated, and the results of the first year's work in a building of very low insulating capacity are described in this paper. The climatic conditions during this year, i.e. 1946–7, were very abnormal, a very cold winter followed by a hot spell in the spring which provided an abnormally severe test of an uninsulated store. Later papers will consider storage in an insulated building with adequate ventilation.