Effects of biochar replacement in peat on growth and nutritional quality of lettuce

Abstract

为探究生物炭替代草炭用于生菜无土栽培的可行性，以草炭、珍珠岩和蛭石栽培基质为对照（CK），用体积分数5%（BS5）、10%（BS10）、15%（BS15）、20%（BS20）的生物炭替代草炭栽培生菜，分析生菜生长和营养品质指标的变化及其与基质性质的相关关系。结果表明：5%~20%生物炭替代草炭后，各处理基质的容重和碱解氮含量显著降低，总孔隙度、通气孔隙度、速效磷、速效钾、微生物生物量和酶活性显著升高。生物炭替代草炭后，生菜的生长状况均优于对照，地上部和根系干质量分别较对照增加了29.31%~67.24%和50.00%~158.33%；同时，各处理生菜的根系活力、叶绿素、可溶性糖、可溶性蛋白和维生素C含量均显著高于对照。RDA分析结果显示，基质的容重、通气孔隙度、碱解氮、速效磷、速效钾是影响生菜生长和营养品质的主要理化性质因子，而微生物生物量碳、蔗糖酶活性、脲酶活性、微生物生物量氮是影响生菜生长和营养品质的主要微生物学性质因子。研究表明，生菜栽培基质中5%~20%的草炭由生物炭替代是可行的；生物炭主要通过改善基质的孔隙状况、提高养分循环酶活性和有效养分含量来促进生菜的生长和营养品质的提升。

This study investigates the feasibility of replacing biochar in peat for soilless cultivation of lettuce. A mixed substrate of peat, perlite and vermiculite was used as the control, compared with 5%, 10%, 15% and 20% of peat replaced with biochar to analyze the changes in growth and nutritional quality indexes of lettuce, and their correlation with substrate properties. The bulk density（BD）and alkaline nitrogen（AN）content decreased significantly, and the total porosity, aeration porosity, available phosphorus（AP）, available potassium（AK）, microbial biomass（MBC, MBN）and enzyme activity increased significantly with biochar replaced peat. The growth of lettuce was better than the control, with the dry mass of shoot and root increasing by 29.31%-67.24% and 50.00%-158.33%, respectively. At the same time, the root activity, chlorophyll, soluble sugar, soluble protein and Vitamin C content of lettuce of each treatment were significantly higher than the control. RDA results showed that BD, aeration porosity, AN, AP, and AK of the substrate were the main physicochemical properties factors affecting the growth and nutritional quality of lettuce, while MBC, sucrase activity, urease activity, and MBN were the main microbial properties factors affecting the growth and nutritional quality of lettuce. Replacing 5% to 20% of peat in lettuce culture medium with biochar is feasible. Biochar can promote the growth and nutritional quality of lettuce by improving the porosity of the substrate, nutrient cycling enzyme activity, and the content of effective nutrients.