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University of Tsukuba (2020)

Potato Plants under Drought, Heat, and Combined Drought-Heat Stress : Morpho-Physiological and Molecular Responses

Handayani, Tri

Titre : Potato Plants under Drought, Heat, and Combined Drought-Heat Stress : Morpho-Physiological and Molecular Responses

Auteur : Handayani, Tri

Université de soutenance : University of Tsukuba

Grade : Doctor of Philosophy in Agricultural Science 2020

Résumé
Abiotic stress is the most limiting factor in crop yields, as it interferes with crop growth and development. Drought stress and heat stress are the major abiotic stresses hampering world food production. The intensity and distribution of drought and heat stress are becoming more severe with the present climate changes. The increasing average global temperature triggers the uprise of heat stress event, and the decreasing annual mean precipitation in some mid-latitude and sub-tropical regions leads to water deficit. Even more critical is when drought and heat stress occur together in nature. Potato (Solanum tuberosum L.) is the third most important food crop in the world. Although potatoes are grown worldwide over wide agroclimatic zones in various environments and seasons, potato plants require specific physiological conditions for growth and tuber production. High temperatures and water deficits have become the most serious constraints for potato production. Several research groups have examined the effects of drought stress or heat damage on potato, but few investigations of the effects of combined drought-heat stress have been reported. As an addition to the cultivated potato that is sensitive to abiotic stress, the genetic potato resources comprised of landraces and wild potato relatives (which could contribute to tolerance to a range of abiotic stress) have not been well studied. Using diploid breeding lines and a tetraploid commercial potato, I studied how these potatoes respond to drought stress, to heat stress, and to a combination of drought and heat stress. The diploid breeding lines have various landraces and wild relatives’ genetic backgrounds. The morphological and physiological responses of potatoes to PEG-induced drought stress, heat stress, and combined drought-heat stress are presented in Chapter 2. Abiotic stress-related traits were evaluated in a growth-room environment under non-stress and abiotic stress treatments, and the results demonstrated that all of the potato lines responded to the drought and combined drought-heat stress by reducing their plant height. In contrast, the potato lines’ responses to the effect of heat stress on plant height differed ; some heights increased while others decreased. The leaf size in all of the potato lines became viii smaller under drought, heat stress, and combined drought-heat stress compared to the non-stress condition. The potato plants responded to the drought stress and combined drought-heat stress by increasing their chlorophyll content and decreasing their relative water content (RWC). A decrease in water content related to wilting symptoms was observed under drought stress and under combined drought-heat stress. The potato line L1 (84.194.30) showed the lowest level of wilting in all three types of abiotic stress, supported by a small RWC change compared to the control condition ; L1 is thus considered relatively tolerant to abiotic stress.

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Page publiée le 4 juin 2021