CHRYSANTHEMUM DRY-MATTER PARTITIONING PATTERNS ALONG IRRADIANCE AND TEMPERATURE-GRADIENTS

The influence of photosynthetic photon flux (PPF, 1.8-21.6 mol d-1 m-2) and day (DT) and night (NT) temperature (10-30-degrees-C) on dry matter accumulation and partitioning was studied in Chrysanthemum morifolium Ramat. 'Bright Golden Anne'. Total plant dry matter varied from 3.6 to 17.2 g at flowering. Plants with the greatest dry matter were from treatments with high PPF levels and temperatures. Accumulation of dry matter in roots, stems, leaves and flowers examined on a normalized time and normalized dry matter basis showed similar trends independent of DT, NT and PPF during development. Accumulated dry matter in roots, stems and leaves increased to a maximum and then decreased as the flowers were developing. Maximum leaf, root and stem dry matter was reached at 81, 85 and 91%, respectively, of required time from start of short days (SD) to flower. Proportion root dry matter increased and proportion leaf dry matter decreased in the plants as PPF increased. Partitioning to roots decreased as the DT increased. The root/shoot dry matter ratio decreased as plants developed from start of SD to flowering at all studied combinations of PPF, DT and NT. A positive difference between DT and NT (DIF) resulted in a higher percentage stem dry matter compared to plants grown at a negative DIF. Partitioning to flowers was not strongly correlated with the levels of PPF, DT and NT.