Nutritional control of the correlative inhibition between lateral shoots in the flax seedling (Linum usitatissimum)

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Abstract
When the epicotyl of the flax seedling is decapitated one of the two shoots produced at the cotyledonary node tends to inhibit and may completely suppress the growth of the other. By growing the seedlings in sand culture with a controlled mineral nutrient supply it was shown that (a) the inhibiting influence of the dominant shoot was inversely related to the nitrogen level; (b) the inhibited shoot could be released from inhibition by increasing the nitrogen supply; (c) the removal of the dominant shoot was followed within 12 h by an increase in the total nitrogen content of the inhibited shoot; (d) a similar control of inhibition could be obtained by varying the phosphorus supply. These results are consistent with the hypothesis that this form of correlative inhibition is due primarily to competition between the shoots for a limited mineral nutrient supply.When one of the cotyledons was either covered or removed its axillary bud was inhibited by the shoot in the axil of the untreated cotyledon. The degree of inhibition was inversely related to the nitrogen supply. It is suggested as a working hypothesis that the cotyledons provide a factor(s) which promotes the growth of their axillary buds and thus determines their ability to compete for mineral nutrients.