Amino-acids in the root and bleeding sap of tomato plants

SUMMARY 1. In experiments with tomato plants the relationship between the amino-acids of root and bleeding sap were studied. 2. The amino-acid content of the root is variable and shows a daily periodicity with a minimum in the daytime. 3. A positive correlation exists between the amino-acid content of the root and the amino-acid concentration of the bleeding sap, but the amino-acid and the sugar content of the root are negatively correlated. 4. Succinic acid given to the root, may act not only as an amino-acid precursor but also as an energy source and as such it may, if sugar is limiting, increase the bleeding rate. 5. The nitrogen source of the nutrient solution is important; ammonium increases the amino-acid content of the root more than nitrate does. 6. Both the transpiration stream and the phloem stream influence the amino-acid content of the root; the transpiration stream by transporting amino-acids out of the root and the phloem stream by supplying sugars to the root. 7. Fruiting decreases vegetative growth; the amino-acid and sugar content of the root is decreased in fruiting plants and these facts influence in their turn the amino-acids, transported in the bleeding sap. 8. Environmental conditions, such as the amount of light, given to the shoot, the composition and the amount of nutrient solution, influence the sugar and keto-acid content of the root and, consequently, the amino-acid content. ... Zie: Summary