THE EFFECT OF COTYLEDON EXCISION ON THE GROWTH OF PEA SEEDLINGS

Pea plants grown under controlled conditions for 28 days were sampled nine times during this growth period. On each sampling day 80 plants were harvested. Cotyledons were excised from 40 plants and the root‐shoot axis allowed to continue growth. The other 40 plants were divided into roots, shoots, and cotyledons; the dry weights of alcohol‐water extracts and residues from these organs were determined. Shoot lengths, numbers of nodes, buds, flowers, and fruits of 28‐day‐old plants, whose cotyledons were excised at different times, were determined. These data indicate that cotyledon excision after the 13th day has no apparent effect on seedling growth, whereas excision before the 13th day reduces growth. Glucose‐U‐C 14 supplied to attached cotyledons of 6‐ and 16‐day‐old seedlings resulted in no major difference in the distribution pattern of recovered label throughout the plant even though 16‐day‐old cotyledons were depleted of their normal endogenous food reserve.