Determination of assimilate partitioning at different growth stages of potato plant under water stress conditions

Timing of water stress relative to tuber initiation is critical in determining patterns of assimilate partitioning. Water stress early in the season (during stolon formation) reduces the number of stolons and subsequent initiation of tubers.Thus, severe and prolonged stress from early in the season constrains tuber formation causing assimilate to be partitioned to other organs. However, water stress imposed after stolon formation i.e. at the time of tuber initiation stage promoted the tuber initiation due to enhanced assimilate partitioning, consequently the number of tubers were increased at tuber initiation stage. It is also found that root and shoot growths are strongly affected by partitioning of dry matter to tubers during an early phase of tuber bulking [2]. An interesting finding was observed in number of tubers at different growth stages. Water stress imposed at tuber initiation stage (T2) caused 50% to 80% increase in number of tubers whereas tuber number was reduced when water stress was imposed at tuber enlargement and tuber maturity stages. Increase in number of tubers due to water stress at tuber initiation stage can be explained on the basis of assimilate partitioning to tubers.