难溶性磷对紫花苜蓿生长、根系分泌有机酸及根解剖结构的影响研究OA

Phosphorus is an essential nutrient for the growth and development of alfalfa(Medicago sativa L.).To evaluate differences among varieties in phosphorus utilization under insoluble phosphorus conditions,a hydroponic experiment was conducted using insoluble phosphate[Ca3(PO4)2,IP]as the treat-ment and water-soluble phosphate(KH2PO4,SP)as the control.Six alfalfa varieties,'Longdong'(M1),'Glodqueen'(M2),'Algonquin'(M3),'Zhongmu No.1'(M4),'Gannong No.9'(M5),and'Giant energy No.2'(M6),were assessed for growth performance,phosphorus uptake,root organic acid secretion,and root anatomical characteristics in order to clarify the mechanisms of phosphorus utilization under insoluble phosphorus supply.The results showed that aboveground dry weight under IP was lower than under SP for all varieties.Under IP treatment,'Zhongmu No.1'exhibited the greatest aboveground dry weight,reach-ing 1.90 g,whereas'Gannong No.9'showed the lowest aboveground dry weight at 1.00 g.'Zhongmu No.1'also had the highest aboveground phosphorus content at 0.39%under IP,while'Longdong'hade the lowest value at 0.25%.All six varieties displayed increased organic acid secretion under IP compared with SP,with citric acid as the predominant component.'Zhongmu No.1'secreted significant higher amounts of total organic acids and citric acid than the other varieties.Insoluble phosphorus supply altered root anatomi-cal structure,and clear varietal differences were observed.'Gannong No.9'had the largest number of xylem vessels but the smallest vessel diameter,whereas'Longdong'showed the largest root diameter and stele diameter under IP treatment.Pearson correlation analysis indicated that aboveground dry weight of alfalfa was significantly positively correlated with root malic acid secretion(P<0.01)and positively corre-lated with xylem vessel diameter and cortex thickness(P<0.05).Aboveground phosphorus content was also significantly positively correlated with tartaric acid secretion(P<0.05).Grey correlation analysis iden-tified'Zhongmu No.1','Longdong',and'Giant energy No.2'as superior varieties under insoluble phospho-rus conditions.These varieties demonstrated strong potential utilizing insoluble phosphate resources and are suitable candidates for cultivation in soils with low phosphorus availability.