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In this experiment, the hydroponic way to study the regulation of nutrient solution on lettuce (Lactuca sativa L.) growth, yield and quality. Test different from before harvest to stop nutrient solution supply time, segmented management of nutrient solution concentration of Different Nitrogen Forms and different nutrient solution concentrations of four parts. . Stopped nutrient solution for the fluid before harvest time (12 days, eight days, four days, 0 days) affect the growth and quality of lettuce (varieties of the 'Hongnong' and 'Qingfeng'). The results show that, stop nutrient solution for the liquid for more than 8 days before harvest, aboveground fresh weight, dry weight, number of leaves, leaf length, leaf width, leaf water content significantly reduce the with stop solution time extension and root fresh weight, dry weight, and root to shoot ratio increased significantly; treatment compared with control (stop solution 0 days), four days before harvest to stop the supply of nutrient solution had no significant effect on the growth of lettuce. Lettuce leaf nitrate reductase activity, soluble sugar content with the stop before harvest time extension of the nutrient solution supply and significant increase in lettuce nitrate content decreased significantly, four days before harvest to stop nutrient solution soluble protein and The content of vitamin C had no significant effect, but time over eight days to stop nutrient solution significantly reduces the lettuce soluble protein and vitamin C content, indicating that four days before harvest stop solution process is more suitable for lettuce hydroponic method. Lettuce leaves and roots of organic nitrogen, phosphorus, potassium, calcium and magnesium content decreased gradually with the lengthening of the time of the suspension of nutrient solution. 2. The nutrient concentration segmented Management (1s-1s-1s; 2s-1/2s-1s; 1s-2s-1/2s; 1/2s-1s-2s) that management model of four concentrations (control ; high - low - in; - high - low; low - medium - high) to study its impact on the growth and quality of lettuce lettuce (varieties for the 'Hongnong' and 'Qingfeng'). The results show that, in - high - low \shoot and root growth. In the lettuce three different growth stages, early low nutrient concentration can promote growth, high concentration is not conducive to the fresh weight, dry weight and leaf area increase, the high concentration of the mid-and late management of shoot fresh weight, dry weight and the increase in leaf area. \. \, calcium and magnesium content. \Using four different Nitrogen Forms (NO 3 - -N: NH 4 -N were 100:0,75:25,50:50 and 0:100) study the different nitrogen forms on hydroponic lettuce (varieties growth of \With the increase in the proportion of nitrogen in ammonia nitrogen, shoot and root fresh weight, dry weight gradually reduce the number of leaves, leaf length, leaf width, leaf water content were significantly reduced, and the root to shoot ratio is with the significant increase in the proportion of ammonia nitrogen and rise; Different Nitrogen Forms processing shoot growth at 10 days after planting showed significant differences. Lettuce nitrate content decreased gradually with the increase in the proportion of ammonia nitrogen, nitrate reductase activity gradually increased. Chlorophyll content is also increased with the increase in the proportion of ammonium nitrogen. With the increase in the proportion of nitrogen in ammonia nitrogen, SOD and POD activity gradually increased, SOD and POD activities highest a completely ammonia nitrogen treatments.
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