几种沉水植物营养繁殖体萌发的光需求研究

LIGHT DEMAND FOR BROOD-BUD GERMINATION OF SUBMERGED PLANT

对4种沉水植物营养繁殖体萌发的光需求进行了初步的实验研究。结果证明,强光照射可以打破菹草繁殖芽的休眠,促使其在夏初萌发,推论菹草繁殖芽的夏季休眠可能与其所处的水底光照不足有关。苦草、黑藻及金鱼藻营养繁殖体的萌发无需光刺激,但当水底相对光照强度小于5％时形成白化苗,不能进行正常的光合作用。沉水植物营养繁殖体萌发期的水底光照条件是决定沉水植物能否再生的关键因素。

Experimental studies were carried out on the basic light demand for brood-bud germination of submerged plant Vallisneria spiralis L. , Hydrilla verticillata Royle, Ceratophyllum de-mersum and Potamogeton crispus L. Intense light stimulation could break dormancy of brood-buds of P. crispus and lead to germination in the early summer: In natural water body, summer dormancy of P. crispus brood-buds may be caused by low light intensity in the bottom. Light was not indispensable for brood-bud germination in the other three plant, but low relative radiation intensity (less than 5 %) would cause albino young shoot which could not carry out normal photosynthesis. Thus, light condition at lake bottom in brood-bud germinating season was the key environmental factor for submerged plant to survive.