摘要 : A two-year experiment (2004-2005) was conducted at Tal Amara Research Station in the Bekaa Valley of Lebanon to evaluate the influence of progressive application of K rates and application timing on yield, yield components and tub... 展开 A two-year experiment (2004-2005) was conducted at Tal Amara Research Station in the Bekaa Valley of Lebanon to evaluate the influence of progressive application of K rates and application timing on yield, yield components and tuber quality of potato (<i>Solanum tuberosum</i> L. cv. Agria). Four levels of potassium (0 (K₀), 75 (K₇₅), 150 (K₁₅₀), and 225 (K₂₂₅) kg K₂O ha^-1) and two application timings (tuber initiation and tuber bulking stages) were used in a split-plot design. The progressive application of potassium fertilizer from 0 to 225 kg K₂O ha^-1 significantly affected the yield and yield components of potato. In both years, small grade tubers and aggregate tuber yield increased quadratically with increasing K application rates up to 150 kg K₂O ha^-1, reaching a plateau thereafter, showing luxury consumption of the nutrient at 225 kg K₂O ha^-1. In 2004 when averaged over K application rates, large and medium grade tubers and aggregated tuber yield were 120%, 22%, and 12% greater, respectively, with K application at tuber bulking than at tuber initiation. A similar trend was also observed in 2005, when the small grade tubers and aggregate tuber yield were 20% and 12% higher, respectively, with K application at tuber bulking than at tuber initiation stage. Finally, no significant difference among treatments was observed for tuber dry matter (avg. 19.8%) and specific gravity (1.08 g cm^-3). 收起