Translocation of photosynthetic assimilates in wheat

When ¹⁴CO₂ was supplied to three varieties of wheat in the field translocation of carbohydrates took place freely throughout young plants, but after the stems elongated the tillers became autotrophic. The efficiency with which carbohydrate was translocated to the grain increased during the first 4 weeks after anthesis and then fell. Translocation from the glumes and flag leaves was almost entirely towards the grain; that from the second and third leaves was partly towards the grain and partly downward, with evidence of varietal differences in behaviour.