Effects Of Water Fertilizer Coupling On Yield,Quality And Soil Physical And Chemical Properties Of Allium Mongolicum

Sand onion is a valuable wild resource in typical sandy and arid areas,with high edible,medicinal,forage and ecological values,and is highly appreciated by people.To study the effects of water-fertilizer coupling on yield,quality,nutrient uptake and utilization and soil physicochemical properties of sand onion,a multivariate nonlinear regression model of each index with relative water content,nitrogen application,phosphorus application and potassium application was established using a four-factor,five-level quadratic orthogonal rotational combination design（1/2）implemented with the introduced Gansu Minqin sand onion as the experimental material.Main effect analysis,single factor effect analysis and coupled water-fertilizer effect analysis were conducted,and model search for superiority was performed for yield and quality of sand onion,and water-fertilizer management measures for high yield and quality were identified,respectively.The comprehensive quality evaluation was performed by principal component analysis,and the comprehensive quality ranking was performed for different water and fertilizer treatments,and the comprehensive scores were modeled to find the best.The main findings were as follows:1.Relative water content had the greatest effect on the yield of sand onion,followed by the amount of nitrogen,phosphorus and potassium applied.All water-fertilizer interactions had a positive effect.The optimized water and fertilizer regimen for sand onion yield above 16.83 g/pot was obtained by frequency analysis:76.61%-79.44%relative water content,353-383 kg·hm^-2 N,172-192 kg·hm^-2 P₂O₅,and 210-236 kg·hm^-2 K₂O.2.Phosphorus application had the greatest effect on soluble sugars and total flavonoids.The interaction of water nitrogen on quality had a positive effect,and the interaction of water phosphorus and water potassium had a negative effect.The integrated water and fertilizer management practices for onions with soluble sugar content higher than 4.475%were obtained by frequency analysis:79.73%-82.28%relative water content,277-291 kg·hm^-2 N,171-178 kg·hm^-2 P₂O₅,and 306-325 kg·hm^-2 K₂O.The integrated water and fertilizer management practices for onions with total flavonoids higher than 2.936 mg/g were:72.46%-74.17%relative water content,281-293 kg·hm^-2 N,197-207 kg·hm^-2 P₂O₅.and 249 to 262 kg·hm^-2 K₂O.3.Nitrogen application had the greatest effect on phosphorus content of sand onion,followed by relative water content,potassium application and phosphorus application.Potassium application had the greatest effect on potassium content of sand onion,followed by phosphorus application,relative water content and nitrogen application.Nitrogen application had the greatest effect on water use efficiency,followed by relative water content.Relative water content had the greatest effect on fertilizer bias productivity,followed by phosphorus application.The water-fertilizer interaction had a positive effect on both water use efficiency and fertilizer bias productivity.4.The effect of irrigation on soil p H was greater than that of fertilizer application,and the effect on soil conductivity and fast-acting phosphorus was less than that of fertilizer application,while potassium application had the greatest effect on soil fast-acting potassium,followed by irrigation.Flooding increased total phosphorus and fast-acting phosphorus,but decreased conductivity,total nitrogen and fast-acting potassium.Fertilizer application increased conductivity,total phosphorus,fast-acting phosphorus and fast-acting potassium.5.The results of the integrated quality evaluation of different water and fertilizer combinations by principal component analysis showed that treatment 14 had the highest integrated score of 1.275.Through frequency analysis,the comprehensive water and fertilizer management measures that can achieve efficient,high-quality and sustainable production of Allium mongolicum are selected as follows:72.80%-76.56%relative water content,375-409 kg·hm^-2 N,265-285 kg·hm^-2 P₂O₅,183-217 kg·hm^-2 K₂O.