LONG-TERM RESPONSES OF MELILOTUS-SEGETALIS TO SALINITY .1. GROWTH ANDPARTITIONING

Annual sweetclover plants [Melilotus segetalis (Brot) Ser.] were grown for a complete life cycle with and without saline (NaCl treatment of CE=15 dS m(-1)). Growth and partitioning analyses were performed. Sequ ential harvests (every 15 d) during the life cycle, and separation of plant material into roots, stems, petioles, leaves and reproductive st ructures were carried out. Salt treatment reduced growth during the ea rly and middle stages of the life of the plant, but did not significan tly affect RGR in the reproductive phase. The root-shoot allometric co efficient of salinized plants in the generative phase decreased more t han in control plants. We suggest that salinity-induced growth reducti on in M. segetalis was primarily a result of a lower unit leaf rate (U LR) despite an increased leaf area ratio (LAR). Earlier flowering, hig her biomass allocation to shoot and greater reproductive investment, b ut similar relative growth rate (RGR), were some of the main character istics of salt-stressed plants compared to controls during the reprodu ctive phase, these apparently being associated with increased sink str ength caused by developing flowers and fruits.