Early Understandings of Plant Growth ■ FLemish(佛兰德人) chemist_ JB van Helmont(early 17th century) noted that the bulk of the plant came from water ■ Added5| b of willow cuttings(柳树枝条)to 200 b of dried soil a Covered soil pot but allowed water to enter After five years, he harvested willow cuttings and soil
◼ A Flemish（佛兰德人） chemist—J B van Helmont (early 17th century) noted that the bulk of the plant came from water ◼ Added 5 lb of willow cuttings（柳树枝条） to 200 lb of dried soil ◼ Covered soil pot but allowed water to enter ◼ After five years, he harvested willow cuttings and soil Early Understandings Of Plant Growth
Tablel: Van Helmont' s willow tree experiment(1648) 1. Weight of dry soil 200b(91kg) 2. Initial weight of the 5b(23kg) tree(fresh weight) 3. Final weight of the 169b(768kg) tree(fresh weight) 4. Weight gain of the 164b(745kg) tree. fresh weight) 5. Weight gain of the tree 16 Ib(7. 45kg) (dry weight) 6.Weight loss of the soil(dry 2 oz(57g) weight) 7 Percent loss from soil (dry.06% weight)
Table1 : Van Helmont's willow tree experiment (1648) 1. Weight of dry soil 200 lb (91kg) 2. Initial weight of the tree.(fresh weight) 5 lb (2.3kg) 3. Final weight of the tree.(fresh weight) 169 lb (76.8kg) 4. Weight gain of the tree.(fresh weight) 164 lb (74.5kg) 5. Weight gain of the tree (dry weight) 16 lb (7.45kg) 6. Weight loss of the soil (dry weight) 2 oz (57g) 7. Percent loss from soil (dry weight) 0.06%
Early Understandings of Plant Growth After 5years growth Willow cuttings weighed 169 Ib Dried soil weighed 199 1b. 14 OZ Only 2 oz of soil was lost Suggested all the remaining weight came from water. The water was in some way transmuted into plant tissue What was wrong with him?
• After 5years growth: • Willow cuttings weighed 169 lb. • Dried soil weighed 199 lb. 14 oz. • Only 2 oz of soil was lost • Suggested all the remaining weight came from water. The water was in some way transmuted into plant tissue. • What was wrong with him? Early Understandings Of Plant Growth What are plant nutrients?
Van Helmont's willow tree experiment 1643 648 2.3 kg 77kg
1648 77kg 1643 2.3 kg Van Helmont’s willow tree experiment
Early Understandings of Plant Growth What is particularly important about this study is that it represented the first documented attempt to evaluate plant nutrition by experimental means rather than by accepted dogma(教义、教条) The directness, simplicity and taking of quantitative measurements in his experiment played an important role in developing the experimental approach of the future
• What is particularly important about this study is that it represented the first documented attempt to evaluate plant nutrition by experimental means rather than by accepted dogma（教义、教条）. • The directness, simplicity and taking of quantitative measurements in his experiment played an important role in developing the experimental approach of the future. Early Understandings Of Plant Growth