| This article discusses the effect of too little or too much phosphate fertilizer on the growth and development of walnut seedlings.Taking the freshly harvested annual walnut seedlings as research materials,different gradient phosphorus concentrations were set to study the effects of different phosphorus supply levels on individual plant growth,physiological and biochemical indicators,photosynthetic characteristics,and nutrient content in the treatment room and rhizosphere of walnut seedlings.In order to provide some references for walnut seedling breeding and the efficient utilization of phosphate fertilizer in direct seeding and effective garden construction,the effects of phosphate fertilizer dosage on walnut seedlings were investigated.The main research results are as follows:?1?The growth of walnut seedlings has a certain regulation effect on the response of phosphate fertilizer.The appropriate amount of phosphorus application was beneficial to the growth and development of leaves and roots of walnut seedlings,and the plant height,ground diameter,stomatal number,total root tip number and fractal dimension were the largest under the treatment of L4(30g·plant-1)phosphorus concentration,which increased by 40.70%,24.67%,58.36%,4.28%and 2466.59%,respectively,compared with the control group.?2?There were significant differences in the response of physiological and biochemical indexes of walnut seedlings to each treatment of phosphate fertilizer.The acid phosphatase?ACP?and free amino acids in the leaves of walnut seedlings reached the highest values under phosphorus treatment at L1(0g·plant-1),8.27nmol/?min/mg protein?and 11.31?g·g-1,respectively.Nitrate reductase?NR?,soluble sugars,and soluble proteins all had peaks in the L4(30g·plant-1)phosphorus treatment,which were 117.59?gNO2-.g-1FW.h-1,70.89mg·g-1,40.95mg·g-1.Phosphorus,potassium,calcium,and magnesium in rhizomes and leaves showed a straight-line change trend with increasing phosphorus concentrations,while nitrogen,boron,iron,manganese,molybdenum,sulfur,and zinc showed an"increasing-decreasing"trend.?3?Different phosphorus concentrations had different effects on chlorophyll content and photosynthetic indicators of walnut seedling leaves.The maximum value of chlorophyll in L4(30g·plant-1)phosphorus treatment was 26.89mg·g-1,an increase of 40.27%.Photosynthetic parameters Pn,Gs,Ci and Tr all had the highest values in L4 treatment(30g·plant-1),which were8.08umol·m-2·s-1,0.18mmol·m-2·s-1,327.94umol·mol-11 and 5.61mmol·m-2·s-1,respectively.Except for Ci,the variation of the photosynthetic index showed a parabolic trend of opening up in one day,the other indexes all showed a bimodal trend,which was from 12:00-14:00 and 18:00-20:00 in the time period.?4?Phosphorus gradient had a significant effect on the nutrient content in the soil of walnut seedlings during treatment and in rhizosphere.The total nitrogen and total phosphorus of the walnut seedlings in the 20 cm and rhizosphere soils increased with the increase of the phosphorus gradient and reached the maximum values of 0.78 g·kg-1,1.47 g·kg-1,and 0.70 g·kg-1,1.41 g·kg-1in L5 treatment,the total potassium content shows a"down-rise-down"trend with increasing phosphorus gradient,the pH value shows a"up-down-rise"trend,and the conductivity shows a parabolic trend with the opening upward.In summary,different phosphorus concentrations have corresponding regulation mechanisms on the growth and development of walnut seedlings.Phosphorus gradient treatment ranked by principal component analysis:L4(30g·plant-1),L3(20g·plant-1),L5(40g·plant-1),L2(10g·plant-1),and L1(0g·plant-1). |
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