Tomato plants were grown in sand culture at 8 levels of K ranging from 0 to 10 meq per liter of nutrient solution. Fully ripened fruit were picked and rated internally and externally for abnormal pigmentation. Total carotenoids were analyzed and the extract fractionated into 3 groups: hydrocarbon, monohydroxy and polyhydroxy. The hydrocarbon fraction was further separated chromatographically into 6 individual pigments. Most of the carotenoids, lycopene in particular, generally increased with increasing K concn. A notable exception to this pattern was β-carotene which decreased with increasing K concn. Possible modes of action of K are discussed.
Floral induction of broccoli (Brassica oleracea italica) ‘Waltham 29’ at low temp (5°C) was associated with increasing levels of starch and sugar in the shoot tip. This same relationship was found in experiments concerning plant age, duration of cold treatment, leaf removal before and during cold treatment, and treatment with succinic acid 2,2-dimethylhydrazide (SADH) or gibberellic acid (GA3).
Greenhouse experiments with plants grown continuously at 16-21°C or 21-27°C indicated that high carbohydrate levels are not necessarily associated with flowering. Flowering was delayed at the higher temp with little difference in carbohydrate level.
The distribution of l4C-assimilates was examined in pot-grown ‘Redkote’ and ‘Michelite-62’ bean plants in which a lower or upper leaf was dosed with 14CO2 at flowering, pod expansion, or pod maturation. Assimilates from the leaf at node 4 moved primarily to the roots at flowering, but were translocated to actively growing pods at later stages. Dosing of the terminal trifoliate of ‘Redkote’ resulted in radiocarbon transfer exclusively to the subtending pods during pod expansion and maturation. Distribution from leaves on branches of both varieties was restricted to pods on the branch. When the main-stem node-7 leaf of ‘Michelite-62’ was dosed, 51% of the activity was recovered from node-7 axillary pods, and less from pods at nearby nodes. Thus middle and lower main-stem leaves of beans generally supply assimilates to several centers of active growth, while distribution from upper mainstem and branch leaves is more restricted.