Plantain (<i>Plantago lanceolata</i> L.) Leaf Elongation and Photosynthesis Rates Are Reduced under Waterlogging

Abstract

Plantain (Plantago lanceolata L.) has been identified by the New Zealand dairy sector as an option for reducing nitrogen losses from grazed pastures. However, there is growing concern over its poor persistence. Reports have suggested that plantain does not tolerate waterlogged soils; however, there is little scientific evidence to support those claims. Thus, the present study aimed to investigate the impact of waterlogging on plantain growth and survival. In a glasshouse, three water treatments were applied to plantain plants in pots: control (soil water below field capacity but not limited), wet (soil water marginally above field capacity), and waterlogged (water table 5 cm below the surface) for 39 days, followed by 27 days under the control watering treatment. Leaf elongation and photosynthesis were measured during the experiment. The mean leaf elongation rate of waterlogged plants was 37% lower than control plants during the stress period, but not significantly different than control plants during the recovery period. Waterlogging reduced the rate of photosynthesis in plantain leaves by 15% on average in comparison with control watering during the stress period; however, waterlogged and control plants had a similar mean photosynthesis rate during the recovery period. The results show that plantain growth and photosynthesis were significantly limited under waterlogging; however, the rapid recovery of both processes following the removal of stress suggests that important physiological functions remained intact under waterlogging, possibly due to tolerance mechanisms. These findings suggest that while waterlogging may cause limitations for plantain growth, there is no evidence to suggest that it alone could cause irreversible damage to plants and thus prevent their recovery. Rather, waterlogging stress could undermine the ability of plantain to compete with species that are tolerant of waterlogging within mixed pastures.

Keywords

• narrow-leaved plantain
• plant stress
• stress tolerance
• flooding