| A series of research methods including soil-less culture, pot experment and chemical analysis were adopted to study the effects of six organic manures (Rape Cake-RC, Maize Straw-MS, Pigg Manure-PM, Rice Straw-RS, Chicken Manure-CM, Peat Powder-PP) and five nutrient ratio of NPK on nitrate content in foliage vegetables (celery and romaine lettuce) in soil-less culture and to investigate the effects of NPK combination, organic-inorganic fertilizer and nitrate regulators (fertilizer, chemistry and nature type) on growth, nitrate-N of lettuce leaf, yield, nitrate content and quality of lettuce leaf and stem in pot experiment. The research results were as follows:In soil-less culture, six organic manures decreased the root weight, height and yield (except PM treatment increase by 21.1%, PP treatment markedly decrease by 32.4%) of celery on the basis of inorganic fertilizer, but all treatments could increase the yield of romaine lettuce from ?5.5 % to 132.7 % and the effect was in order of RS>CM>PP>MS >RCH?N > HNp > BNPK > RC>P7> HKN > Mic + P7. At W30 (30% soil moisture), excepting HKN and D+Mic treatments .other treatments could increase the yield by 2.8% to 35.1%, and the order of the increscent was PM>HNp>RC>HpN>BNpK>P7>Mic+P7>Mic.At W35(35% soil moisture), different treatments boosted the yield of lettuce by 13.0 % to 39.6% (except HKN and D+Mic treatments), in which the order was HNP>PM>HPN>BNPK>RC>Mic >Mic+P7>P7.With the increscent of soil moisture (from W25, W30 to W35), the yield of lettuce was obviously exalted. Under different soil moisture, the ratio of yield had remarkably difference, which was in the order of Yw35/Yw2s(from 1.61 to 1.99 times) >Yw3o/Yw2sCfrom 1.32 to 1.56 times) >Yw35/YW3o(from 1.10 to 1.34 times).The effects of HPN, BNPK, HNp, RC and RM treatments on yield of lettuce were better at three level of soil moisture, which showed that soil moisture was very important to the yield and had much effect on the yield of lettuce.With the difference of soil moisture, fertilization and growth stage, the content of nitrate-N in lettuce leaf had different change trait. Under three levels of soil moisture, with the postponement of lettuce growth stage , the change of nitrate-N content in lettuce leaf could be divided into four types: decreasing type, increasing-decreasing type, decreasing-increasing type and increasing type.At the same growth stage ,with the increscent of soil moisture, the change of nitrate-N content in lettuce leaf also took on four ty... |
