Potato tuberization in hydroponics
Creators: name: Yang, Simon Shengyuan
Publisher: name: University Of Tasmania
Year: 2023

description: The project investigated potato tuber initiation in hydroponics and was initiated by Sunrise Seed Potatoes Pty Ltd, a company specialising in potato minituber production in Tasmania, Australia. The initial focus of the project was to describe in detail the rate and timing of stolon and tuber development in nutrient film technique (NFf) hydroponics. A developmental scale consisting of five stages, each based on characteristic morphological changes, was developed to enable quantitative evaluation of the effects of experimental treatments on tuberization. Nutrient uptake rate at plant development stages was studied in different seasons. Uptake rate of water and nutrient elements generally displayed a decline from early to late stage regardless of season. Uptake rate of H+ displayed significant variation between seasons and did not follow the characteristic decline. A novel system for frequent and accurate non-destructive assessment of stolon and tuber growth using webcams and image analysis software was developed and validated. Stolon and tubers displayed a diurnal growth pattern with rapid elongation commencing mid to late afternoon and ceasing early morning, followed by a period of slower growth rate often leading to cessation of growth or shrinkage at around midday. Growth rate varied under different seasonal and environmental conditions and between stolons of the same plant. The initiation of stolon tip swelling always occurred in the late afternoon or early evening. This was the first report of the precise timing of the commencement of stolon swelling in potatoes. The timing of swelling initiation coincided with the timing of the rapid growth of stolons and tubers in the diurnal cycle. Tissue turgor in swelling tips was always higher than in elongating stolons measured during the rapid plant growth period. Under inductive conditions, stolon turgor at midday was found to be higher than under non-inductive conditions. This provided evidence that turgor may be part of the stimulus for potato tuber initiation. Further evidence supporting this theory was gained in an experiment where stolon water potential was altered over a short period when initiation of swelling had just commenced in a hydroponic crop. Stolon turgor at the period of rapid elongation was decreased by adding polyethylene glycol (PEG) to the nutrient solution or increased by replacing the nutrient solution with distilled water. Rate of tuber initiation was decreased in the PEG treatment and increased in the distilled water treatment compared with standard nutrient solution. This study demonstrated that NFT hydroponics is a valuable system for the whole plant study of potato tuber initiation. The system facilitated non-destructive assessment of stolon and tuber development and also the compact size of the experimental system enabled treatments such as photoperiod and temperature to be applied. Characteristic stolon diurnal growth patterns were documented for the first time using the NFT hydroponic system, and this permitted the identification of the timing of swelling of stolon tips. Turgor potential was proposed as part of the stimulus for tuber initiation, with implications for potato crop management as manipulation of turgor may be used to influence tuber initiation. Further investigation of water relations under different inductive and non-inductive treatments will improve our understanding in this exciting new area of study in potato tuberization.