Physiological responses to reduced water availability in potato (Solanum tuberosum) crops

Huntenburg, Katharina and Dodd, Ian (2022) Physiological responses to reduced water availability in potato (Solanum tuberosum) crops. PhD thesis, Lancaster University.

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Irrigation is an important factor in potato crop management to maximise yield. Summers in the UK will be hotter and drier in the future due to climate change. To maintain crop productivity and use ground water resources sustainably, it is important to determine how potatoes regulate their water use and yield under reduced soil water availability. To better understand root-to-shoot signalling and water fluxes above and below-ground in potato under water-limiting conditions, this thesis presents data from the field and plants at specific phenological stages grown in controlled environments. Potatoes were grown in the field in a factorial combination of soil compaction and deficit irrigation for an entire season, to understand responses to limited plant water availability. Although physiological parameters (stomatal conductance, photosynthesis rates, leaf tissue ABA) did not differ between treatments throughout the season, plant growth (ground cover, leaf length and number) and yield were reduced under both stresses. Shoot biomass mid-season was correlated with final tuber yield across all treatments. A possible role of the tuber in regulating plant water relations has been little investigated. Magnetic resonance imaging (MRI) was used as a novel technology to monitor tuber volume growth and water content in vivo in well-watered plants and plants from which water was withheld for two days and then re-watered. Plant physiological parameters indicated drought stress prior to re-watering. Tuber volume growth varied diurnally with most growth occurring at night in well-watered plants. However, nocturnal tuber growth ceased immediately after withholding water. Re-watering on Day 3 recovered tuber volume of drought stressed plants to well-watered values. Strigolactones (SL) have recently been identified as root-to-shoot signal under drought stress, inducing stomatal closure. However, stomatal conductance and leaf water potential of three transgenic lines of potato impaired in SL biosynthesis or signalling or hypersensitive to SL (ccd8, d14 and d53 respectively) were similar to the wildtype as the soil dried. Contrary to previous findings in tomato and Lotus, stomatal density was lower in the SL insensitive and SL deficient line and higher in the SL overexpressing line, but these differences did not alter water use. In summary, this thesis employs a novel technique (MRI) and previously undescribed transgenic lines (d14, d53) in potato to better understand how drying soil affects physiological processes. While irrigation of the potato crop is important in early development and at tuber bulking stage, there may be scope to decrease irrigation at the tuber initiation and maturity stages. Further research is needed to understand the genotype x environment interactions of SL signalling in drying soil.

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Thesis (PhD)
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08 Mar 2022 12:45
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11 Jun 2024 23:32