Abstract: Through dynamic monitoring on hydroponic lettuce growth and mineral nutrient change,provide theoretical basis for reasonable and effective management of hydroponic lettuce nutrient.By adopting deep hydroponic method,setting five nitrogen concentration,respectively 9,8,6,4,3 mmol/L,systematically learned the influence of different nitrogen levels on lettuce yield,quality,utilization efficiency and dynamic absorption of mineral elements.The results showed that under different nitrogen level the difference of lettuce dry matter accumulated more and more significant over time,when nitrogen levels was 6 mmol/L,lettuce obtained maximum yield.Lettuce nitrate increased first and then slightly decreased as the nitrogen increasing,and reached the maximum when the nitrogen level was 8 mmol/L,Vc and soluble protein increased constantly as the nitrogen increasing,and the content reached the highest when nitrogen level was 9 mmol/L,the soluble sugar increased first and then decreased as the nitrogen increased,and gained the maximum levels when nitrogen level was 6 mmol/L.As the nitrogen level increased,the utilization efficiency of P,K,Ca,Mg of lettuce showed a trend of increase first and then decrease,nitrogen utilization efficiency of lettuce linear decreased.High concentration of nitrogen level helped improve the lettuce on the absorption of nitrogen and phosphorus,while low nitrogen level helped improve the absorption of potassium,calcium and magnesium.The absorption of nitrogen and phosphorus were mainly concentrated in the 20-30 d after planting,average uptake respectively accounted for 64.81% and 61.88% of the whole growth period,the absorption of potassium reached the maximum in the 30~40 d after planting,the average absorption was 44.46% of the whole growth period,the lettuce on the absorption of calcium and magnesium were relatively uniform after planting.When nitrogen level was 8 mmol/L,lettuce absorption of mineral elements gained highest in the whole stages,which was 582.31 mg/plant,by this time,the lettuce obtained good yield and quality,higher efficiency utilization of P,K,Ca,Mg,but the nitrogen use efficiency was lower.

Key words: Hydroponic lettuce, Nitrogen, Growth, Mineral elements, Dynamic change

CLC Number: 

• S143.1