This thesis addresses the mechanisms underlying the response of plants to drought and heat stress. Water and temperature are important factors for normal plant growth and development. However, when their values are outside the normal range, the plant experiences stress and attempts to cope with it through various physiological, metabolic and anatomical adaptations. In general, these mechanisms are divided into escape, avoidance and tolerance to drought or heat. For example, plants can tolerate drought through different adaptations: osmotic adjustment, increased cell membrane elasticity and reduced cell size. In this thesis, the two stress factors are considered first individually and then in combination. For each stress factor, examples are given of the genetic background of these mechanisms, important knowledge for breeding of new drought- and/or heat-tolerant cultivars. Particular attention should be paid to the co-occurrence of drought and heat stress, as it is more frequent in practice than the two stress factors individually. Temperatures are expected to continue to rise in the future, and with them also the frequency and intensity of droughts. Among other practices, the development of new tolerant varieties is an important tool to ensure food security in the face of a growing world population.
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