Characteristics of Leaf Water Potential and Photosynthetic Rate of Blueberry Plants Grown Under Drought Stress

Abstract

This study investigated the changes in leaf water potential (Ψ L ) and photosynthetic rate (Pn) of cropping and non-cropping blueberry plants grown under drought and re-watering conditions. Nine-year-old 'Tifblue' plants grown in a pot were used. When plants grown under drought conditions, Ψ L and Pn of leaves decreased as soil water content decreased. Pn decreased to near zero when Ψ L was approximately -3.5 MPa and soil water content was approximately 8%. Under that condition, all fruits and some shoots wilted and some fruits dropped. Pn of cropping plants decreased more rapidly than that of non-cropping plants, under drought conditions. After re-watering, Ψ L and Pn of plants grown under drought conditions were increased and then these values reached half the level of plants grown under well-watered conditions. The rate of increase in Pn in cropping plants was slower than that in non-cropping plants under drought conditions. The values of stomatal conductance and transpiration rate showed a tendency similar to that of Pn. These results showed that the critical point of Ψ L for recovering plant vigor was less than -3~-3.5 MPa. Furthermore, drought stress was promoted by fruit loading.

Influence of drought stress on the photosynthetic characteristics and dry matter accumulation of hybrid millet

“…Normally, the first symptom of drought stress becomes evident at stomatal level. Stomata reduce their degree of opening to prevent desiccation (Ramanjulu et al 1998, Flexas and Medrano 2002, Liu et al 2004, Horiuchi et al 2011, Li et al 2011, Yan et al 2012. photosynthesis is affected by internal water deficiency following stomatal closure.…”