Effects of pineapple straw ditch burial and reduced potassium fertilizer application on growth，development， yield and quality of pineapple

<bold>Objective</bold> This study aims to clarify the advantageous role of pineapple straw trench burial and return to the field in pineapple production，as well as the partial replacement effect of pineapple straw on potassium fertilizer. <bold>Method</bold> A split-plot design was adopted in this experiment.The main factor consisted of four returning methods of pineapple straw，namely no straw returning，and furrow burial returning at depths of 10 cm，20 cm，and 30 cm.The sub-factor included two potassium application rates：conventional potassium application and reduced potassium application，resulting in a total of 8 treatments.This study aims to investigate the effects of furrow-buried pineapple straw returning combined with reduced potassium application on the growth and development，nutrient accumulation，yield of pineapple at different growth stages，as well as soil properties at the maturity stage. <bold>Result</bold> Compared with non-returned soil，trench-buried returned soil can increase soil organic carbon content and available nutrients in certain soil layers，thereby improving the number of leaves，leaf area index，total dry matter，yield，nitrogen，phosphorus，and potassium accumulation，and fertilizer absorption efficiency during the mid-to-late growth stages of pineapples.Among the treatments，the 30 cm trench burial treatment yielded the best results，significantly increasing the content of nitrate nitrogen and available potassium in the deep soil layer，as well as the content of ammonium nitrogen and available phosphorus in the 0-40 cm soil layer.It also increased the number of leaves in the middle and late growth stages of pineapples by 21.28%-32.39%，the leaf area index by 34.16%-49.25%，total dry matter yield by 34.35%-41.17%，and nitrogen，phosphorus，and potassium accumulation by 7.98%-48.08%.It also increased vitamin C and soluble protein content in pineapple fruits.Compared with conventional potassium fertilizer application，reduced potassium fertilizer application under straw trench burial did not reduce the number of pineapple leaves，leaf area index，total dry matter，yield，cumulative nitrogen，phosphorus，and potassium content，or nitrogen and phosphorus fertilizer absorption and utilization rates.It also significantly increased potassium fertilizer absorption and utilization rates by 18.10%-54.53% and had no negative impact on soil physical and chemical properties.Correlation analysis indicated that yield was significantly positively correlated with soil organic carbon content，nitrate nitrogen content，available phosphorus content，plant leaf number，leaf area index，total dry matter yield，potassium accumulation，nitrogen，phosphorus，and potassium fertilizer utilization rates，as well as fruit soluble sugar content，titratable acid content，and vitamin C content. <bold>Conclusion</bold> Straw trench burial at 30 cm combined with reduced potassium fertilizer application can improve soil quality，enhance pineapple growth and development，promote nutrient absorption，and maximize yield increases，making it the optimal pineapple cultivation management model for hot regions.