1. Potato Variety Response to Phosphorus Fertilizer Mike Thornton, Deron Beck, Jeff Stark and Bryan Hopkins

2. Petiole P status and yield are related Source: Westermann and Kleinkopf, 1983 Y = 237 + 7.24X – 0.026 X 2 R 2 = 0.76

3. Daily uptake rate of P during three years at Aberdeen, ID Source: Stark, Westermann and Hopkins, 2004

4. Cultivar use in 2007 Idaho Oregon Washington Shepody

5. 6LS

6. Do potato varieties differ in their response to P fertilizer? Differences in yield response Differences in yield response Differences in P uptake or petiole levels Differences in P uptake or petiole levels Differences in P removal by tubers Differences in P removal by tubers  Varieties with poor root systems or susceptibility to early die might need more P

7. YearpHLimeSoil P (ppm) Broadcast (P 2 O 5 /ac) Starter (P 2 O 5 /ac) 20058.21%15130 lbs40 to 80 lbs 20067.72%8210 lbs40 to 80 lbs 20078.21%5290 lbs40 to 80 lbs Soil test values (0 to 12”) UI recommendation Methods -Split plot design with 4 rates of P 2 O 5 (0,100, 200, 300 lbs per acre) broadcast as 11-52-0 and incorporated prior to planting. Urea used to balance N rates. -Four cultivars (Burbank, Ranger, Shepody, 6LS) planted as subplots

8. Influence of fertilizer rate on marketable yield

9. Russet Burbank6 LS Influence of fertilizer rate on tuber size profile

10. Vine Growth

12. Influence of fertilizer rate on plant growth

13. Deficient Influence of fertilizer rate on petiole P concentration

14. Influence of fertilizer rate on plant P uptake on Aug 15

15. Influence of fertilizer rate on P removal in tubers

16. SUMMARY Plant development was delayed and senescence increased at low P rates, especially in Shepody Plant development was delayed and senescence increased at low P rates, especially in Shepody Petiole P levels were highest in Ranger, lowest in Russet Burbank and 6LS Petiole P levels were highest in Ranger, lowest in Russet Burbank and 6LS Ranger and 6LS had the strongest yield response to fertilizer P, and removed up to 33 lbs/acre P in tubers at harvest Ranger and 6LS had the strongest yield response to fertilizer P, and removed up to 33 lbs/acre P in tubers at harvest

17. For information about potatoes, visit: Idaho Center for Potato Research and Education http://www.ag.uidaho.edu/potato