Source–Sink Relationships in Potato Plants

Аннотация

Using the method of labeled atoms, we investigated the operation of the source–sink system in potato plants grown at the northern border of the cultivation zone. The label was introduced photosynthetically by means of exposing individual leaves or the whole above-ground part of plants to air containing ¹⁴СО₂ in different stages of their growth and development. It was shown that the export of assimilates from the leaves depended on their age, position on the stem, and the stage of ontogenesis. Young leaves of the lower layers became donors early and exported the products of current photosynthesis to the stems and roots maintaining their own growth with the substrates from the parental tuber. The stems attracted two times more ¹⁴С-assimilates than the roots. The leaves of the middle layers had the greatest area, exported ¹⁴С directly to the tubers, and spent up to 40% of assimilated carbon on their own needs. Apical leaves emerging by the end of the vegetation period accumulated approximately 10% of ¹⁴С-products of photosynthesis, and the rest of them were exported directly to the tubers. Exposure to a short-day length stimulated partitioning of carbon to the tubers in potato species notable for an obligate short-day response of tuberization (Solanum andigenum Juz. et Buk.), whereas reduction in the daily duration of photosynthesis suppressed accumulation of biomass of tops and tubers in commercially grown potato with a neutral response (Solanum tuberosum L.). In the course of tuber formation, respiration consumed 35% of initially assimilated ¹⁴С, which points to a high efficiency of storage of carbohydrate polymers in the form of starch. The obtained data broaden the knowledge about organization and operation of source–sink relationships and provide a basis for elaboration of the methods of governing potato plant’s source–sink system in an effort to improve productivity of this major crop.