engleski

Morphological and Physiological Modulation of Pepper Transplants after Prolonged Exposure to ABA

Elucidation of abscisic acid (ABA) role in plant growth or as signaling compound under environmental stressful conditions received considerable attention during the past decade. Whether ABA application can modulate transplant growth in the nursery and thus improve early acclimation during stand establishment in the field is not well known. This study evaluated the effect of ABA at 0, 0.1 or 1.0 mM applied as foliar spray for 5, 10 or 15 consecutive days on pepper transplant growth and physiology. All measured parameters were taken one day after the last ABA application for each treatment. ABA at 0.1 mM had a slightly positive effect on net photosynthetic rate after 5 or 10 days of continuous application, but negative after 15 days compared to control plants. Transplants exposed to 1.0 mM ABA for 5 or 15 days have reduced photosynthetic rate and stomatal conductance. Leaf xylem water potential increased and stem elongation decreased with ABA after 10 or 15 days of exposure. Shoot weight and leaf area were maintained with ABA at 0.1 mM, irrespective of exposure time, but with 1.0 mM ABA growth was lower compared to control. Root weight was generally less affected than shoot weight leading to increased root to shoot ratio by ABA treatment. Application of 1.0 mM ABA for 5 or 15 days enhanced total and specific root length (root length/root weight). This study suggests that continuous ABA application can modulate pepper transplants growth and physiological responses, being the rate of change dose and duration dependant.

abscisic acid; Capsicum annum; gas exchange; shoot; root

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