LIPID UTILIZATION AND CARBOHYDRATE PARTITIONING DURING GERMINATION OFENGLISH WALNUT (JUGLANS-REGIA)

Conversion of reserve lipids in the seed, and carbohydrate and dry mat ter partitioning during germination were studied in walnut (Juglans re gia L cv Franquette) seedlings. Nuts showed a gradual decrease in lipi d content with a concomitant rise in carbohydrates (fig 2); starch app eared to be a transient sink for the end products of the degradation o f lipid reserves. During germination, tap root elongation was preferen tial over stem growth (fig 3). The tap root accounted for most of the seedling dry matter increase and carbohydrate accumulation mainly as s tarch (table I). The other organs accumulated essentially soluble carb ohydrates. At the end of the experiment, only 26.7% of the carbohydrat es (starch + soluble carbohydrates) from lipid conversion were recover ed in the seedling and the nut. A similar discrepancy was found in the energy budget. The energy loss from the nut (76.391 kJ) and the total energy recovered in the seedling (30.985 kJ) differed markedly at the end of the experiment (fig 4); this difference of 59% can be attribut ed to the metabolic lipid conversion, respiration (growth and maintena nce) and translocation (table II).