The effect of nitrogen form on the growth, photosynthesis and phosphorus uptake by sunflower plants
2001
Borowski, E.
Seedlings of sunflower after germination grew for 1 week in Hoagland solution. After that, plants were transferred for 2 weeks to nutrient solution differing with regard to nitrogen form and the level of phosphorus. In the nutrient medium three nitrogen forms (NO3, NH4, CO(NH2)2 and two levels of phosphorus (0 or 32 mg/cubic dm) were used. The results showed that plants fed with N-NO3 had greater fresh mass and total leaf surface than plants fed with N-NH4 or CO(NH2)2. The application of N-NH4 increased the rate of photosynthesis and the content of phosphorus in all parts of plants. Deprivation of an external P decreased the fresh mass of leaves and stems and the total leaf surface on plant but it had no effect on net photosynthesis. The relation of inorganic to organic phosphorus in plants without P in nutrient solution was 0.4-0.5 while in plants properly equipped with P it was 1.0-1.9
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