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[Objective]The effects of the same fertilizer rate under different fertilization modes on potato growth and yield were studied to provide references for establishing a suitable and better fertilization mode for Yunshu40l with high yield and good quality. [Method] Using Yunshu401 as the research object, the field test was carried out, with conventional fertilization for 50% IN+ 100% P + 100% K as basic fertilizer, seedling topdressing 50% IN as the control, and six different NPK ratio fertilization treatments in seedling and budding stage. The basis of the same amount of fertilizer was 300 kg/ha urea, 1125 kg/ha calcium superphosphate, and 600 kg/ha potassium sulfate fertilizer. The growth and yield indicators of various treatments were determined. [Result]The test results showed that at seedling stage topdressing 50% IN+30% K processing, potato plant height was the highest (91.0 cm), significantly higher than that of other treatments (p<0.01, the same below). No significant difference was seen among the processed potato stem and branch number. The difference of tuber number per plant between staging fertilization and the control was not significant. Stem diameter(1.15 cm) with seedling topdressing 50% N+50% P+30% K processing was significantly lower than that of other treatments (P<0.05, the same below). Stem diameter (1.61 cm) with seedling topdressing 50% N+30% P+30% K was significantly higher than that of the control. Seedling topdressing 50% N + 30% P+30% K had the highest yield (43311.0 kg/ha), followed by sub-seedling fertilizer (50% N+50% K) and the bud of fertilizer (20% N+20% K) treatment (41809.5 kg/ha), which were significantly higher than the control. [Conclusion] Yunshu401 topdressed a small amount of phosphate fertilizer at seedling stage in the seedling stage or seedling and budding stage, graded topdressing nitrogen and potash is beneficial to improve the yield and the commodity rate. At seedling stage topdressing 50% N+30% P+30% K or sub-seedling fertilizer (50% N+50% K) and the bud of fertilizer (20% N+20% K) treatments can be used as Yunshu40l high efficient and yield cultivation mode of fertilization in northeast of Yunnan Province and similar ecological zones. [ABSTRACT FROM AUTHOR]

The replacement policy for a deteriorating system subject to cumulative shocks is studied. Assume that each shock arriving in the system's operating time can cause a random damage to the system, the damages are additive, and the system fails once the accumulated amount of damages exceeds a prefixed threshold. When a failure occurs, we can repair or replace the system. For such a deteriorating system, we assume that the thresholds are geometrically decreasing in the number of repairs taken, and the consecutive repair times form an increasing geometric process. By adopting the replacement policy N of that the system is maintained after the previous (N - 1)th failures and is replaced at the time of the Nth failure, we derive the explicit expression for the long-run average cost rate (ACR), and determine the optimal policy N* for minimizing the long-run ACR. A numerical example is also given. [ABSTRACT FROM AUTHOR]