Effects Of NPK Concentration On Yield,Quality And Element Utilization Efficiency Of Hydroponic Celery

Plant factory is production technique of high efficiency based on modern agricultural facilities and high-tech cultivation skill, with the superiority of high land productivity, labor productivity and economic benefit. Hydroponic is the main way of plant factory and its solution formula would decide yield and quality of vegetables. Researchers at home and abroad in the study of soilless cultivation were mostly focused on lettuce, while few on celery. This paper conducted the research of hydroponic celery with different NPK density supply to study the effects on yield, quality and element utilization efficiency. Main conclusions obtained are as follows:(1) When nitrogen concentration was set 8 mmol/L, fresh weight and element utilization efficiency of N, P and Ca in hydroponic celery got the highest, content of VC, protein, soluble sugar and nitrate and utilization efficiency of K and Mg ranked only second to that of 10 mmol/L. The increase of the N concentration did not significantly improve nitrogen use efficiency, in treatment of high N concentration, P and K use efficiency was significantly higher than low N concentration. Comprehensive evaluation was conducted on celery yield, quality and utilization efficiency of the main elements by principal component analysis, which showed that 8 mmol/L is the most suitable N concentration for celery hydroponic.(2)Relation between phosphorus concentration and biomass was a parabola going downwards and 0.8 mmol/L led to the peak of biomass. Fitting results showed that phosphorus concentration of 0.590 mmol/L obtained the highest single yield, 0.646 mmol/L for highest nitrate content, 0.579 mmol/L for highest soluble sugar content, 0.561 mmol/L for highest VC content and 0.594 mmol/L for highest soluble protein. Nitrogen use efficiency: P3>P4>P1>P2>P5. K use efficiency of P1, P2 and P3 were basically the same, obviously higher than that of P4 and P5. Calcium utilization efficiency presented a rule of increase first and decrease then. P5 processing obtained the lowest efficiency and P4 highest, with a ratio of 56.53 percent. Water use efficiency of P3 treatment was significantly higher than other treatments. Comprehensive evaluation by principal component analysis showed that 0.6 mmol/L is the most suitable P concentration for celery hydroponic.(3) Effects of K concentration on biomass was parabolic open to the bottom, and 5 mmol/L concentration got the maximum. Fitting analysis showed that the K concentration of 3.79 mmol/L gained the highest single yield. The K concentration for maximum content of nitrate content, soluble sugar and soluble protein was respectively 1.671, 4.474 and 9.308mmol/L. With the increase of concentration of K supply, VC content increased. Water use efficiency presented a increase first and decrease then as the K concentration increased, and the peak appeared at 4 mmol/L. All elements utilization efficiency were higher when K concentration was low Comprehensive evaluation by principal component analysis showed that 6 mmol/L is the most suitable K concentration for celery hydroponic.(4) A orthogonal experiment on Yamazaki formula celery with three factors of growth stages and four levels of concentration gradients was carried out, which showed that the most appropriate solution concentrations for three stages were 0.25 times, 0.50 times and 1.00 times successively. Among different growth stages, the order of influence of solution concentration on celery yield, from large to small, was the third stage, the second stage, and the first stage. Principal component analysis results showed that 16 th treatment(with concentration 0.25, 0.50 and 1.00 at three stages respectively) obtained the highest comprehensive evaluation index, while the 6th(with concentration of 0.75, 1.00, 1.00) got the worst. The optimization scheme from range analysis of ground dry and fresh weight was C2B4A4(with concentration 0.25, 0.50 and 0.75 respectively at three stages), and that of underground dry and fresh weight was B3A3C1(with concentration 0.50, 0.75 and 1.00 respectively at three stages).