| In people’s daily life,vegetable is indispensable food,it provides abundant aminoacids,vitamins,minerals and cellulose for ahuman.Leaf vegetables are classifiedas high nitrate accumulation crops and this phenomenon is aggravated by high nitrogen fertilizer application in vegetable production.But in recent years alarge number of people for the pursuit of high nitrogen fertilizer adding nitrate accumulation in vegetables,which poses potential a threat to people’s health.Spinach(Spinacia oleracea L.)is rich in nutrition,contains vast protein,vitamins,folic acid,amino acid,dietary fiber and iron,calcium,magnesium and other minerals.Spinach is a very popular vegetables in China,and it has play a decisive role in demand of resident and supply in the market.But spinach also has high nitrate accumulation.In this study,spinach is choiced as material,we screen out high and low nitrate accumulate cultivars,and study the difference from physiological aspects,in order to offer theoretical basis to cultivate low nitrate spinach and technical guidance.The main results are as follows:1.In the nutrient solution and soil culture conditions,there are significant differences in different spinach genotypes.We choose leaf as a sampling sites because it is the sensitive part of nitrate accumulation.In the nutrient solution culture conditions,the highest varieties of nitrate content is SL-26-13,up to 882.8 mg/kg;and the variety SL-34-13 is the lowest,only 169.1mg/kg,the former for the atter 4.2 times.In the soil cultivation conditions,the nitrate content of spinach varieties "bofeite" is the highest,up to 1626.3 mg/kg;and the variety SL-34-13 is the lowest,only 338.1mg/kg.And the former is 3.8 times higher than the latter.For subsequent test,two kinds of cultivation conditions,SL-26-13 and "bofeite"were screened out as varieties which has high nitrate content,and SL-6-13 and SL-34-13 werechoosed as cultivars with low nitrate content.2.This test choose the method of nutrient solution cultivation,the varieties with high nitrate ontent has higher content of photosynthetic,low pigment photosynthesis rate,higher absorption of nitrate,and low nitrate reductase activity;the varieties with low nitrate content has low photosynthetic pigment content,stronger photosynthesis,low nitrate uptake rate and higher nitrate reductase activity.No significant correlation between the biomass and nitrate content of spinach.The causes of nitrate content difference betweenspinach genotypes may be affected by the nitrate uptake and translocation.3.This test choose the method of nutrient solution cultivation,the higher genetype’bofeite’ has higher contents of soluble protein,vitaminC and soluble sugar,and its nutritional quality is good.But its content of nitrate,nitrite and oxalic acidcontent is higher,and its the health quality is poor which is not conduciveto the safety of people’s diet.While in variety SL-34-13,the content of soluble protein vitamin C and soluble sugar is lower than’bofeite’,but it has a lower contentof nitrites and oxalates.Compared with the high nitrate genotypes,the low genotypeshas the higher activities of antioxidant enzymes in the leaves and lower in roots.Therefore,the antioxidant enzyme activity and quality do not hae significant correlation with nitrate content of spinach,but it can prove material and theoretical basis for breeding low nitrate vaties with good quality varieties and higher antioxidant enzyme activity.4.In this experiment,with the increase of nitrogen concentration,soluble sugar、vitamin C、soluble protein content and the activity of antioxidant the activity of antioxidant of two kinds of spinach increasing first and then decreased,the content of oxalic acid decreasing first and then increased,and the nitrate and nitrite keeping increased.N8 is suitable for the growth of spinach,under this concentration,the nutritional quality and health quality of two kinds of spinach is the best and also has higher activities of antioxidant enzymes.In this situation,antioxidant enzyme activity of low nitrate genotype is higher,and its quality is better. |
