DRY-MATTER AND NITROGEN ACCUMULATION AND PARTITIONING IN FIELD-GROWN WINGED BEAN

Growth and the partitioning of dry matter and nitrogen were studied in winged bean 'SLS-40' grown with single stake supports at two sites in Sri Lanka. Plant parts (leaves, petioles, stems, roots, nodules, flowers, green pods, mature seeds, and mature pod-walls) were collected periodically, if present, for up to 32 weeks after emergence. Slow growth up to the seventh week was followed by rapid growth (2.8 g plant-1 day-1) for the next 15-17 weeks. Little leaf senescence was observed and the nitrogen content of the leaf tissue remained close to 45 mg N g-1 throughout growth. The rate of nitrogen accumulation was 2.3-2.7 kg N ha-1 day-1 between weeks 13 and 32. The final accumulation of nitrogen in the above ground material was 280 to 312 kg N ha-1, only 34% of that being in the mature seed. The harvest index for dry matter was 17.5-20% and the dry seed yield almost 2 t ha-1.