沼液对水培生菜光合特性、产量及品质的影响

为了阐明沼液替换营养液比例与水培生菜生育阶段、产量、品质及光合特性之间的关系,筛选出最佳沼液替换比例,采用深液流水培法,以生菜为材料,研究了不同生育阶段沼液替换比例对生菜产量、品质及光合特性的影响,并分析了叶绿素a与光合参数的关系。结果表明,沼液替换部分营养液显著提高了生菜产量(P0.05),且不同生育时期沼液对生菜产量的影响规律一致,当生菜生长中期(第2个生育阶段)沼液替换比例为20%,末期替换比例为40%时生菜生物量最高,高出CK(以原山崎配方配制营养液水培生菜)66.97%;沼液替换部分营养液的各处理的生菜可溶性糖与CK相比显著提高,且差异极显著(P0.01);可溶性蛋白有一定程度提高,但差异不显著;生菜的硝酸盐量显著降低,同时生菜VC量随着沼液置换比例的增加而降低。沼液替换部分营养液提高了生菜叶片叶绿素a,促进生菜光合作用的进行。故生菜第2个生育阶段沼液替换营养液对生菜产量、光合特性及品质调控效应较好,且以40%沼液替换比例效果最佳。

Effect of Biogas Slurry on Photosynthesis,Yield and Quality of Lettuce Grown in Hydroponic Culture

We investigated the impact of replacing part of the nutrient solution by biogas slurry on yield, quality and photosynthesis of lettuce grown in hydroponic culture at different growing stages using deep flow technique (DFT). The relationship between chlorophyll-a and photosynthetic parameters was also analyzed. The results showed that the lettuce yield increased significantly after partially substituting the nutrient solution by biogas slur-ry (P<0.05), and this is consistent in all growth stages. The yield peaked when 20％of nutrient solution was sub-stituted by biogas slurry during the second growth stage and 40％during the last growth stage, with the yield in-creasing by 66.97％compared with the CK (no biogas slurry). Substituting the nutrient solution by biogas slurry substantially increased the soluble sugar compared with the CK (P<0.01), but there was not noticeable change in the soluble proteins. It was also found that biogas slurry reduced the amount of nitrate, decreased the vitamin C, enhanced chlorophyll-a in the lettuce, as well as promoted the photosynthesis. In summary, substituting part of the nutrient solution by biogas slurry in second growth stage of the lettuce grown in hydrophobic culture in-creased its yield, quality and photosynthesis, with 40％of the medium substituted by biogas slurry most optimal.