To overcome the reduced extension growth of the coleoptile which occurs when oats are grown in air enriched with 5 per cent. CO1, plants have been provided with nutrients via the roots. 2 per cent, sucrose, glucose or mannitol so applied further promoted the mesocotyl and further depressed the coleoptile. Root growth was also depressed. To induce promotion of coleoptile growth by externally applied sucrose, seedlings were heated in darkness at 40° C. for 3 hours so restricting selectively the growth of the mesocotyl. Promotion of the coleoptile, however, was not observed. Application of mixed Na and K nitrates occasioned an immediate growth promotion of doleoptile and leaves in both the presence and absence of CO2, and also a.much less pronounced promotion of the mesocotyl in CO2; there was no effect in air. This enhanced growth of the coleoptile and leaves was coupled with a correspondingly greater dry weight and also with an increased outflow of reserves from the endosperm into the plumule. Thus, while externally applied sugars seemed not to reach the coleoptile, those made available from the endosperm as a result of improved nitrogen supply were rapidly translocated to it. Simultaneous provision to the roots of nitrate and sucrose did not improve the absorption and translocation of sugar. An analysis of covariance has been computed using the mesocotyl and coleoptile length data together with the outflow from the endosperm and the conclusions so derived are discussed in relation to the problem of growth integration in etiolated oat seedlings.
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C. Mer (1959) studied this question.