Foliar application of 5-aminolevulinic acid for offsetting unfavorable effects of shallow water table on growth and yield in snap bean (Phaseolus vulgaris)

Haris Kriswantoro, Benyamin Lakitan, Aldes Lesbani and Andi Wijaya

Abstract: Shallow water table (SWT) limits volume of aerobic substrate for roots to grow in most terrestrial plants, including snap bean (Phaseolus vulgaris). Aminolevulinic acid (ALA) has been reported to increase plant tolerance to various abiotic stresses. Aim of this study was to evaluate effectiveness of foliar applied ALA in alleviating negative effects of SWT exposure in snap bean plants. In this study, each seed of snap bean was directly sown in 25 cm diameter pot filled with soil manure mix. Foliar applications of ALA at rates of 0, 0.15, 0.30, and 0.45 mM were applied at 14 days after sowing. Three days after ALA application, the plants were exposed to SWT for 20 consecutive days in controllable experimental pools; therefore, water table can be set and maintained at 10 cm below substrate surface. Results of this study indicated that SWT exposure decreased SPAD value, root length, and pod fresh weight. These decreases cannot be counterbalanced by ALA applications at rates up to 0.45 mM. However, application of ALA at rate of 0.30 mM or higher was able to compensate for potential reduction in number of harvested pods. Leaf water status, SPAD value, and proline content were not significantly affected by applications of ALA at rate up to 0.45 mM. After recovery period, root biomass increased despite root elongation was restricted during SWT exposure. Relative leaf expansion rate (RLER) at early leaf development was sensitive to SWT exposure. In general, rate of ALA application up to 0.45 mM was too low for overcoming negative impact of shallow water table in snap bean plants.

Keywords: abiotic stress; partial saturation; Phaseolus vulgaris; riparian wetland; root growth; stress recovery

Date published: 2020-06-29