Stomatal response characteristics as affected by long-term elevated humidity levels

摘要: Restriction of leaf water loss, by stomatal closure, is decisive for plant survival, especially under conditions deficit. This sensitivity stomata to low potential attenuated high relative air humidity (RH ≥ 85%) during growth, which impedes the plant’s ability survive when subsequently exposed lower humidities due a negative balance. thesis focuses on extent existing variation and reasons underlying cultivar differences in their tolerance RH, as well rate reversibility adaptation elevated RH course ontogeny. Cut rose was used model plant. An experiment postharvest relations three contrasting cultivars showed that sensitive (i.e. steepest decrease cut flower longevity) underwent higher increase loss compared tolerant cultivars. Preventing vascular occlusion considerably extended time wilting grown at showing result growth can only be detrimental keeping quality limiting uptake conditions. Further investigation large genotypic regulation development closing capacity key element this process. The degree anatomical features were affected functionality impaired not correlated. However, density, longer pore length depth contributed RH-grown leaves (16–30% effect depending cultivar). Reciprocal change functioning no level after full expansion. expanding always able partly adapt new level. For started but completed expansion transfer moderate earlier switch took place better loss. behaviour experiencing shift from related with increasing population exceeding critical length. Contrary this, initially transferred exhibited poor functioning, even occurred very late suggests various developmental stages similarly prone ability, these had been prior Key words: abscisic acid, cuticular permeability, heterogeneity, hydraulic conductivity, aperture, humidity, Rosa hybrida, anatomy, conductance, initiation, malfunctioning, population, proximity, vase life.