不同铵硝比对菠菜生长、安全和营养品质的影响

通过水培试验,研究了等氮条件下5种不同铵硝比对菠菜生长和品质的影响。结果表明:(1)从铵硝比100∶0到0∶100,菠菜地上部鲜重不断增加,铵硝比为0∶100时,菠菜的鲜重达最大值;但铵硝比25∶75和0∶100两个处理菠菜的干物重没有显著差异(p<0.05)。(2)随着铵硝比的降低,菠菜茎叶中硝酸盐、亚硝酸盐的含量均表现为线性增加;菠菜茎叶中可溶性草酸的含量和营养液中铵硝比之间呈现出二次曲线相关,在铵硝比为25∶75时,菠菜茎叶中草酸含量最低。适当增施铵态氮有利于降低菠菜硝酸盐、亚硝酸盐及草酸的含量。(3)增铵可以提高菠菜Vc含量,铵硝比为50∶50的处理菠菜Vc含量最高;随着铵硝比的下降,菠菜茎叶中可溶性糖的含量逐渐降低,而粗蛋白的含量则以铵硝比25∶75处理最高。

EFFECTS OF NH4+-N/NO3--N RATIO ON GROWTH,FOOD SAFETY AND NUTRITIONAL QUALITY OF SPINACH (SPINACIA OLERACEA L.)

A solution culture experiment was conducted to study effects of NH₄⁺-N/NO₃^--N ratio on growth,food-safety and nutrition of spinach.The following results were obtained. (1) Fresh weight of spinach shoots gradually increased with the percentage of NO₃^--N in the total nitrogen,and spinach supplied with NO₃^--N as its sole nitrogen source was the highest in biomass,but there was no significant difference (p<0.05) in dry matter weight between treatments,25:75 and 0:100 in NH₄⁺-N/NO₃^--N ratio. (2) Contents of nitrate and nitrite in spinach shoots increased linearly with the decrease in NH₄⁺-N/NO₃^--N ratio.A significant quadric relationship was observed between the percentage of NO₃^--N in the total nitrogen and soluble oxalate content of the spinach shoots,and in Treatment 25:75 in NH₄⁺-N/NO₃^--N ratio,the soluble oxalate content was the lowest.Obviously,proper partial replacement of NO₃^--N by NH₄⁺-N is beneficial to decreasing contents of nitrate,nitrite and oxalate in spinach. (3) Proper partial replacement of NO₃^--N by NH₄⁺-N increased Vc content in spinach shoots,and it was the highest in Treatment 50:50 in NH₄⁺-N/NO₃^--N ratio.Content of soluble sugar in spinach shoots gradually decreased with the NH₄⁺-N/NO₃^--N ratio,and content of crude protein was the highest in Treatment 25:75 in NH₄⁺-N/NO₃^--N ratio.