Water limitation alters pea seed compositional traits and the culturable bacterial fraction recovered from the...

Drought is one of the major environmental constraints affecting grain legume production, yet its impact on seed compositional traits remains less understood than its effects on yield. This study evaluated the effects of water limitation on plant growth, seed nutritional and biochemical traits in Pisum sativum L. cv. Tom Thumb. Additionally, culturable bacteria were isolated from the pea rhizosphere to assess whether water limitation was associated with differences in the isolates recovered under the two watering regimes.

Plants were grown under controlled conditions and subjected to well-watered control conditions (80% field capacity, FC) or water-limited conditions (40% FC) until maturity.

Water limitation reduced shoot, pod, seed and total aerial fresh weight, whereas no statistically detectable differences were observed in the corresponding dry weights, pod number, or seed number. Water-limited conditions altered seed phytochemical composition, increasing saponin and flavonoid contents by 95% and 14%, respectively, and decreasing total phenolic content by 11%. ABTS antioxidant activity increased, while DPPH activity showed a marginal decrease. Endpoint-specific comparisons also indicated lower seed nitrogen (N), with a corresponding reduction in N-derived estimated crude protein, and lower zinc (Zn) concentrations, while molybdenum (Mo) showed a marginal decrease. However, none of these nutritional or mineral responses remained supported after false discovery rate adjustment. Culture-dependent analysis of rhizosphere bacteria showed that reduced water availability had limited effects on culturable bacterial abundance, although different bacterial isolates were recovered under the two watering regimes.

Overall, water limitation altered pea seed composition and was associated with differences in culturable rhizosphere bacterial isolates, even when dry reproductive biomass was not detectably reduced.