Effects Of Nitrogen, Potassium And Calcium Combination On Yield And Quality Of Lettuce Grown In Acidic Garden Soil

Lettuce is the leafy vegetable widespread grown in the south China. There are large areas of lettuce in Chongqing, while high yield and high quality of lettuce is limited because of acidification of garden soil, low fertility and imbalance of plant nutrition. At present the research about influence of compounding of nitrogen, potassium and calcium on yield and quality of lettuces are lesser. By amending acid garden soil(pH=5.2) and pot experiment combining with indoor analysis, this experiment filtrated lettuce variety which is fitting to compounding of nitrogen, potassium and calcium in the garden soil, discussed influence of compounding of nitrogen, potassium and calcium on yield and quality of lettuces. Also by the experiment academic reasons were provided for reasonably fertilizing and growing suitable lettuce varieties. The main results were as follows:1. Among Shuangjian, Runnong, Guasihong, Erbaipi, Jianye lettuces, yields of Guasihong, Erbaipi under treatment of N₁₅P₅K₁₀Ca₂₅ were the highest which average yield was 74.9g/pot and 67.7g/pot, respectively. Except of Guasihong, yields of other lettuce varieties under N₂₀P₅K₁₅Ca₂₅ treatment increased. Yields of Runnong and Jianye lettuces were positively correlative with amino acid, while yields of Erbaipi was negatively correlative with amino acid.2. The content of nitrate was in the order of Erbaipi< Guasihong< Shuangjian< Jianye< Runnong and decreased under treatment of N₁₅P₅K₁₀Ca₂₅. Among the lettuce varieties, Guasihong and Erbaipi were the best one in respect to the yield and content of nitrate. The content of nitrogen, potassium, calcium, iron, manganese, copper, zinc of Erbaipi were all in the lowest for the five varieties.3. The content of vitamin C and amino acid of treatments N₁₅P₅K₁₀, N₂₀P₅K₁₅, N₁₅P₅K₁₀Ca₂₅ are higher than other treatments of five asparagus lettuce breeds. The application of calcium is beneficial to the increase of vitamin C and amino acid. The increase content of dissolved sugar in treatment N₂₀P₅K₁₅Ca₂₅ of Guasihong breed reaches to the significant difference compared with the treatments without calcium, and the content of amino acid is also positively related to the application of calcium. The content of dissolved sugar of treatment N₁₅P₅K₁₀ is the highest of all in the nitrogen-varied group and potassium-varied group of Erbaipi breed, but in the treatment N₁₅P₅K₁₀Ca₂₅ decreases. The content of protein increased as the nitrogen increases in the nitrogen-varied group of the five asparagus lettuce breeds, while the content of protein in stems and leaves in treatment N₁₅P₅K₁₀Ca₂₅ of Guasihong breed. The treatments N₁₅P₅K₁₀, N₂₀P₅K₁₅ and calcium are beneficial to the improvement of the quality of the five asparagus lettuce breeds in acid soil.4. There were little influence of fertilization on the contents of nitrogen, potassium, calcium, magnesium and manganese (C.V< 20%), while greater influence on the contents of phosphorus, iron, copper and zinc (C.V 10.4 -36.9%). Among the five varieties, the lowest contents of nutrients were observed in Erbaipi except for the larger differences of phosphorus and calcium.5. The yields under different nitrogen and calcium level were higher than CK and reached remarkable difference. The highest yield of these two varieties is under the treatment N₁₅P₅K₁₀. Though the yields of N₁₅P₅K₁₀Ca₅₀ (treatment of middling nitrogen) and treatment of altitude nitrogen were higher than CK, they decreased comparing to N₁₅P₅K₁₀ and N₁₅P₅K₁₀Ca₂₅ (Both were treatment of middling nitrogen). The treatment of N₁₅P₅K₁₀ and N₁₅P₅K₁₀Ca₂₅ had better nutritious and healthful qualities.6. The trend of nitrogen and phosphorus in leaves of Guasihong and Erbaipi, while potassium and calcium in the former was in the same way. There was few influence of calcium on the uptake of nitrogen, phosphorus and potassium.7. The nutrient contents in leaves for Gua sihong were in the order of potassium> nitrogen> calcium> phosphorus>magnesium,while them in stems were in the order of potassium> nitrogen> phosphorus>calciurn>magnesiurn. The N₁₅P₅K₁₀Ca₅₀ treatment resulted in the highest contents of nitrogen, calcium,and magnesium in leaves. However, the highest contents of phosphorus, potassium in leaves occurred in the N₁₅P₅K₁₀Ca₂₅ treatment. The nutrient contents in leaves and stems for Erbaipi were in accordance with the trend of ones for Guasihong. The contents of nitrogen, phosphorus in leaves were enhanced as the fertilizer increases. Compared to the CK,the contents of nitrogen, phosphorus, potassium were increased in other treatments in combination with fertilizer. The contents of nitrogen .phosphorus, potassium in plants were advanced with higher fetiliizer, and the contents of N₁₅P₅K₁₀Ca₅₀ was best.8. The content of phosphorus in leaves for N₁₅P₅K₁₀Ca₂₅, potassium for the control and N₁₅P₅K₁₀Ca₂₅, calcium, magnesium for the control and N₁₅P₅K₁₀Ca₅₀ were higher than in stem for the responding ones. The content of phosphorus in stem of Erbaipi was in the order of CK< N₁₅P₅K₁₀Ca₂₅15P₅K₁₀<. The content of potassium for applying of fertilizer was higher than the control and it was enhanced in the plant with the increase of calcium. The content of calcium in stem was too higher than the control and the highest was obtained for N₁₅K₁₀Ca₂₅- The content of magnesium in stem was in the order of CK15P₅K₁₀15P₅K₁₀Ca₂₅15P₅K₁₀Ca₅₀. For Erbaipi it was in the same way of potassium and calcium except phosphorus in leaves under treatment9. The content of calcium in both new and old leaves of Guasihong and Erbaipi were highest and lowest for treatment H₂O-Ca and HOAC-Ca, respectively. The contents of calcium in three...