Source-sink relationships in radish plant

Abstract

The problem of source-sink relationships in di- and tetraploidal radish plants grown in. hydroponic cultures was investigated in two stages of their development: with intensively growing swollen hypocotyl and in the period of actively accumulating nutrients in the storage organ. It was found, that the proportion, between the mass of organs, their RGR and NAR was very similar in di- and tetraploidal populations, probably owing to a similar rate of photosynthesis and pattern of assimilates distribution. The high variability of swollen hypocotyls size is slightly correlated with the size of the whole aerial part and is not correlated with the rate of photosynthesis in leaves. Partial defoliation of radish plants did not affect the rate of photosynthesis of the remaining leaves. Only in the cotyledones the oldest donors of 14C-assimilates, a slight compensation of photosynthesis was reported. It may suggest, that the rate of photosynthesis in radish plants is not under the control of sink activity. The size of the storage organ have determined in some extent its attractive force and influenced the amount of 14C-assimilates exported from their donors. Translocation of photosynthates from the young, still growing leaves was conditioned mainly by their retention power. Therefore, in young radish plants cotyledons were the main donor of ¹⁴C-assimilates.