In this study, 12 lettuce accessions were grown in four experiments in a nutrient film technique system. In the first two experiments, the treatments consisted of two P concentrations (3.1 and 31 mg·L 21). Lettuce cultivated with 3.1 mg·L 21 of P had a variable shoot and root biomass, root-shoot ratio, P uptake efficiency, and P utilization efficiency, indicating the existence of genetic variation.
Five accessions ('Little Gem,' 60183, 'Valmaine,' BG19-0539, and 'Green Lightning') were considered efficient to P because they produced similar shoot biomass with the low and high P treatments. In the third and fourth experiments, the treatments consisted of two P sources (monosodium phosphate (NaH 2 PO 4) and tricalcium phosphate [TCP; Ca 3 (PO 4) 2 ].
Initially, an extra 5 mM of calcium (Ca) was added to the TCP solution to reduce the TCP solubility and, hence, P bioavailability to plants. All accessions produced the similar shoot and root weights with both treatments, indicating that the TCP treatment did not cause low-P stress to the plants. After, the extra Ca concentration added to TCP was increased to 10 mM, resulting in low-P stress and a significant reduction in the shoot weight of all accessions.
Despite the severe P stress, 'Little Gem' and 60183 were among the accessions with the least shoot weight reduction in the TCP treatment. Variability was observed in root biomass root-shoot ratio among accessions under the TCP treatment, suggesting that lettuce accessions responded differently to P stress conditions.
The genetic variation for P use efficiency (PUE) and PUE-related traits in lettuce grown hydroponically suggests the feasibility of breeding new lettuce cultivars from elite lettuce germplasm adapted to low P availability in hydroponics.
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Kreutz, Gustavo & Bhadha, Jehangir & Liu, Guodong & Sandoya, Germán. (2023). Identifying Lettuce Accessions for Efficient Use of Phosphorus in Hydroponics. HortScience: a publication of the American Society for Horticultural Science. 58. 467-474. 10.21273/HORTSCI17040-22.