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作 者 ：张英鹏1;徐旭军2;林咸永1;章永松1;都韶婷1;李刚1

期 刊 ：植物营养与肥料学报 2006年 12卷 2期 页码：227-232

关键词：硝态氮/铵态氮比例；菠菜；可食部分；硝酸盐；草酸形态；

Keywords:nitrate/ammonium ratio, spinach, edible parts, nitrate, oxalate form,

摘 要 ：采用溶液培养试验研究了营养液中硝态氮/铵态氮比例对菠菜地上部可食部分不同器官硝酸盐以及不同形态草酸累积的影响。结果表明,菠菜地上部生物量随供铵比例从0%提高到50%呈增加趋势而后显著下降。叶片和地上部可食部分的硝酸盐含量和累积量均随供铵比例增加而显著下降;叶柄的硝酸盐含量随供铵比例提高而降低,而硝酸盐积累量则先升高后显著下降。叶片是菠菜积累草酸的主要器官,可溶态草酸与草酸总量分别占地上部的56.3%～89.8%和76.6%～87.4%。可溶态草酸是菠菜体内草酸的主要形态,在叶片、叶柄及地上部中所占草酸总量的比例分别在36.7%～83.5%,79.0%～93.3%以及50.0%～83.0%之间。地上部各器官的可溶态草酸含量、难溶态草酸含量和草酸总量以及积累量均随着供铵比例的增加而显著下降,叶片和地上部的草酸含量和积累量的下降幅度均高于叶柄。可见,调节营养液中硝态氮/铵态氮比例可以有效降低菠菜地上部可食部分硝酸盐和草酸的含量和积累量,50/50是营养液中适宜的硝态氮/铵态氮比例,不仅菠菜的生物量最高,而且硝酸盐和各形态草酸的含量以及累积量较低,从而大大减轻了硝酸盐和草酸对人体健康产生的负面影响。

Abstract:Nitrate and oxalate are two major quality-related compounds present in high quantities in some vegetables such as spinach and deteriorate the nutritional quality of food.Oxalate could lead to the formation of calcium oxalate kidney stones and reduce the bioavailability of calcium,iron and other minerals.Oxalate forms in vegetables have different(effects) on human health,but previous studies have focused mainly on the total oxalate in vegetables.Little is known about how N source can influence content and accumulation of different oxalate forms in vegetable.A hydroponic experiment was carried out to study the effects of nitrate/ammonium ratio in nutrient solution on accumulation of nitrate and oxalates in the edible parts of spinach shoots.Results showed that biomass of spinach increased firstly as ammonium proportion was increased from 0 to 50% then drastically decreased with the proportion of ammonium further increased.Nitrate content and amounts of nitrate accumulation in leaves and shoots reduced markedly with the increase of the ammonium proportion;Nitrate content in petioles decreased with the proportion of ammonium increased while amounts of nitrate accumulation in petioles elevated firstly then markedly reduced.Leaf was the major oxalate-accumulating tissue of spinach,the amounts of soluble oxalate and total oxalate accumulation in leaves constituted 56.3%—89.8% and 76.6%—87.4% of those in shoots,respectively.Soluble oxalate was the predominant form of oxalate of spinach,which in leaves,petioles and shoots occupied 36.7%—83.5%,79.0%—93.3% and 50.0%～83.0% of total oxalate.The content and accumulation amounts of soluble oxalate,insoluble oxalate and total oxalate in leaves,petioles and shoots decreased drastically when the proportion of ammonium was elevated.The extent of reduction of oxalate content and the amounts of oxalate accumulation in leaves and shoots was higher than that in petioles.These results indicate that higher nutritional quality of spinach with lower nitrate and oxalate content and accumulation in edible parts could be achieved by manipulating the(ratios) of nitrate to ammonium in nutrient solution.Appropriate ratio of nitrate to ammonium is 50/50,at which nitrate and oxalate content and accumulation can be markedly reduced without depressing plant growth.

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