Mineral Nutrition and the Target Seedling

Containerized Douglas -fir seedlings were grown in a greenhouse for seven months. Treatments were started in June 1989 by modifying a standard nutrient solution to give three levels each of nitrogen and phosphorus in a complete factorial design. Both nutrients were supplied at one-third of control, control, and three times control. Foliar nitrogen, phosphorus, potassium, total dry weight, and root growth capacity after four weeks were measured in late December 1989. These data were used to compare three methods of assessing plant nutritional status: critical concentration, vector diagnosis, and DRIS (diagnosis and recommendation integrated system). Unlike critical con- centration, both vector diagnosis and DRIS identify rela- tive, not absolute, differences between treatments. Both nitrogen and phosphorus were found to limit growth when compared to the standard nutrient solution. Dry weight was most influenced by nitrogen and RGC was most influenced by phosphorus. Data suggest that the level portion (luxury consumption) of a critical concentra- tion curve is caused by deficiencies in other nutrients. Also, critical concentration was found to be of little value in making nutrient recommendations. Both vector diagno- sis and DRIS were more useful in identifying and ranking limiting nutrients.

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Author(s): William L. Bigg, Jeffrey W. Schalau

Publication: National Nursery Proceedings - 1990

Event: Combined Meeting of the Western Forest Nursery Associations
1990 - Roseburg, OR