COMBINED EFFECT OF THE DROUGHT DURATION AND ELEVATED ATMOSPHERIC C0_2 LEVEL ON PHYSIOLOGICAL AND YIELD PARAMETERS OF WINTER WHEAT

摘要

The unfavourable effects of climate change were studied in terms of changes in the stress tolerance of cereals. The yield and physiological parameters of two winter wheat genotypes (Mv Mambo, Mv Regiment) were analysed in the phytotron after water wascompletely withheld for 7 or 14 days in three phenophases. The plants were raised in climate chambers, one adjusted to ambient C0_2 concentration and the other to a higher level (750 umol mol-1). The aim of the present work was to determine the correlations between the duration of water withholding and the phenological, physiological and yield parameters of winter wheat. It was hoped to identify how elevated C0_2 levels affected the stress sensitivity of plants and whether they contributed to counteracting the damaging effects of drought. In both varieties, the grain mass decreased to the greatest extent when water was withheld at first node appearance (5.9-71.3%). a longer period of drought at first node appearance and grain filling only reduced thegrain number and mass in the case of enhanced C0_2. The yield and physiological parameters of Mv Regiment, however, deteriorated substantially as a result of water deficiency, though this variety was better able to utilise surplus C0_2, giving outstanding results at elevated C0_2 level.