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1982. Dynamics of extractable carbohydrates in Pisum sativum. I. Carbohydrate and nitrogen content in pea plants and cuttings grown at two different irradiances. -Physiol. Plant. 55: 167-173.When pea plants (Pisum sativum L. cv. Alaska) were grown in controlled environment rooms, a stock plant irradiance of 38 W m~^ decreased the rooting ability ofthe cuttings compared to 16 W m"^. Also the origin of the seeds was of importance. The experiments were done in 1976 (1975 seed lot) and 1979/80 (1978 seed lot). At 38 W m~^ the 1975 seed lot produced 7.2 roots, whereas the 1978 seeds produced 20.7 roots per cutting. The eontent of fructose, glucose, inositol and sucrose was determined from an ethanol extract, and extractable starch from a perehlorie acid extract. The irradiance treatment regulated the carbohydrate content ofthe plants at the time they were made into cuttings. Cuttings from 16 or 38 W m~^ contained initially 6.8 and 8.5% carbohydrate on a dry weight basis respectively. If the plants were not excised to cuttings, a stable level of carbohydrates was maintained throughout the growing period, whereas in the cuttings, the carbohydrate content increased five fold during the rooting period. The content of extractable carbohydrates did not show any correlation to the root initiation process, but might be of importance for the further growth of the new roots. The C/N-ratio of the plants at the time they were made into cuttings reflected the pre-growth condition and was not related to the rooting ability of the cuttings.Additional key-words -C/N-ratio, cuttings, relative growth, root formation, starch, stock plants, sugars. B. Veierskov (present address),the ability of the cuttings to fonn roots. Suggestions n ro u on 1^^.^^ \xsx\ made that a high endogenous ievel of nit-In the process of progagating cuttings, not only the rogen enhances shoot growth, which then diverts the rooting environment, but also the growing condition of carbohydrates and other metabolites from the bases of the stock plant strongly influence the rooting ability of the cuttings, resulting in a reduced ability of the cuttings the cuttings. The first findings of a correlation between to form adventitious roots (Mclntyre 1971, Raid 1924, carbohydrate content and rooting ability in cuttings Starring 1923. Starring (1923) concluded, however, were made by Kraus and Kraybill (1918), and have that it was not the ratio but the actual concentration of lately been reviewed by Haissig (1974). It is not only carbohydrate and nitrogen which was of importance for the carbohydrate content, btit also the ratio between the rooting ability of the cuttings. Haissig (1974) carbohydrate and nitrogen which has been related to suggested, that the difference in C/N-ratio in poorly and

Sucrose was supplied to stock plants of Pisum sativum L. cv. Alaska grown at different levels of irradiance. There was no significant effect on the rooting of the cuttings by sucrose supply to intact plants regardless of the irradiance. However, an increase in the number of roots per cutting was obtained at increasing concentrations of sucrose when the stock plants had been grown at 4 W m−2 and their cotyledons had been removed two days before the cuttings were excised. Cotyledons were removed from stock plants at different times before the excision of cuttings with the intent to regulate the endogenous supply of carbohydrate. The number of roots per cutting was reduced by removal of the cotyledons and this reduction was correlated to the number of days the stock plants had grown without cotyledons as well as to the irradiance pre‐treatment. A greater reduction occurred in cuttings from plants grown under 4 W m−2 than from those grown under 38 W m−2. The growth of the stock plants and the subsequent stem growth of the cuttings was determined by the irradiance to the stock plants and by the time of removal of the cotyledons. Exogenous supply of sucrose had no effect on the stem growth of the cuttings.