Shoot growth, root growth and resource capture under limiting water and N supply for two cultivars of lettuce (Lactuca sativa L.)
Background and aims
To improve vegetable crops adapted to low input and variable resource availability, better understanding is needed of root system functioning, including nitrogen and water capture.
This study quantified shoot and root development and patterns of water and nitrate capture of two lettuce cultivars subjected to temporary drought at two development stages (Trial 1) or to continuous, localized drought and/or nitrate shortage (Trial 2).
In Trial 1, early drought slowed down shoot and root growth, whereas late drought enhanced root proliferation in the top 0.1 m. Nitrate capture during drought was sustained by increased nitrate inflow from deeper layers. Plants did not recover fully from drought after re-watering. In Trial 2, root proliferation was stimulated in the drier soil compartment partially compensating reduced water availability and nitrate mobility. Under nitrate shortage, root proliferation was enhanced in the compartment where nitrate was more abundant, irrespective of water availability.
Changes observed in the root system are ‘feed-forward’ mechanisms to sustain resource capture in a limiting growing environment. The type of stress (drought or nitrate shortage) affects coping strategies; nitrate concentration in the soil solution, combined with the nutritional status of the plant will determine the stress response.
KeywordsLettuce Resource capture Resource use efficiency Root system architecture Drought Nitrate Lactuca sativa
Drought Stress applied in the Top compartment
- DST + NSB
Drought Stress applied in the Top compartment combined with Nutrient Stress applied in the Bottom compartment
Dry Weight (g)
Fresh Weight (g)
Nutrient Stress applied in the Top compartment
- NST + DSB
Nutrient Stress applied in the Top compartment combined with Drought Stress applied in the Bottom compartment
Nitrogen Use Efficiency (g DM g−1 N per plant)
Quantitative Trait Loci
Specific Leaf Area (m2 g−1)
Total Leaf Area (m2 per plant)
Total Leaf Number per plant
Total Root Length per plant
Water Use Efficiency (g DM L−1 water)
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